And dissolving it into tetrahydrofuran so this is a complete dissolution the
plastic will dissolve and we now have a solution if you Sonic eight this sample
while the when you first put the PVC toy in typically with the 1530 minute
sonication you'll have a completely dissolve
solution so it makes things a little bit quicker after we have a dissolve
solution will precipitate in hexanes this removes a PVC from the solution so
we'll get a solid precipitate that leaves a phalates in solution makes it a
little bit easier to analyze so we'll move into the analysis step with GCMs
and I'll mention here that the cpsc method allows for several alternative
methods within it this is too important for testing labs of labs already
familiar or likes to use a certain test method that method those that are listed
are available to use instead so generally the alternative methods
usually what differs is the extraction technique and most of them fall into one
of the categories I have listed here a couple of them fall into just a typical
fluid extraction where you're cutting up the sample and you're putting it into a
solvent usually dichloromethane and letting it sit the California Department
of toxic substances method asked just for a 15 minute time and the Health
Canada method is much longer rate 12-hour time so even with this with this
step you have a long range of sample times Sox flu extractions a more of a
aggressive fluid extraction here you have an apparatus that I have shown on
the right where your you have a ground-up sample and the solvent is is
heated and then cool the solvent will come down through the sample so you're
having a continuous extraction with fresh solvent usually the the methods
call for about six hours methods under this category are the the Chinese method
and European methods which I have listed and also EPA methods there's some other
older methods that we we see using this as well there are a couple other
techniques typically found with within the EPA
methodologies they were looking at using different tools for your extraction such
as using a microwave pressurized fluid extraction or ultrasonic extraction and
the common bond here we're looking for is an analysis by GCMs we think this is
important g CMS's are our preferred analysis technique because it's
qualitative and quantitative here I have a chromatogram shown of an analysis with
a standard of all six of the specifically regulated phalates and
generally we're getting a pretty good separation especially for the lower
molecular weight ones and obviously the dno PDI NP + di DP which you see in the
later half the chromatogram alone around 11 12 minutes that's where things get a
little bit trickier and we'll be talking a little bit more about that today we
specified GCMs because some older methods call for GCF ID and simply put
if you're having any overlap and you're chromatogram with different with
different phalates f ID is just not strong enough to get a full qualitative
and quantitative assessment so I'm gonna briefly go over some common problems I'm
gonna give you very very simple problems and very simple solutions that probably
don't do these justice but just to get a the the ideas flowing for discussion
later some common questions we get often people are asked is there a standard
reference material for phalates in PVC another common problem is false positive
results many of manufacturers someone else might say I did not put phalates in
this item I'm sure there's no phalates in this item but the test lab still said
that that there are phalates in this so that could either come under a false
positive result or a result of contamination somewhere along the lines
another issue is the identity of dice and Nona land dice adecco Fowley
both of these phalates actually have multiple cast numbers so there's
different ways of making these compounds and there's a different chemical formula
of these compounds so try it to trying to summarize some of these issues and
solutions as best we can there are multiple issues of the cpsc
method it's been updated a few times we're now on the third version sometimes
people with problems they'll contact us and say well I was following the first
version of this and this is a problem I've had there are there are significant
advancements between the versions so make sure you're definitely using the
most current one we have an interagency agreement with NIST to develop standard
reference materials this has been an ongoing project the last update has been
that they're hoping to have something within the next calendar year we'll see
how that develops but this is a promising idea there's also some
companies that we've seen I believe specs Serta prep has started issuing a
certified reference material they have a specific level of phalates in
polyethylene so that's another frontier you can look with standards companies
they may also be developing their own or looking for something along those lines
I mentioned contamination before this is possible and this is a good question to
ask if you're a manufacturer or seller essentially from the starting points at
the endpoint have I looked at every possible area where phalates can come
into my line we've heard of recycling plastics sometimes people use recycled
plastics that had fights and before and that could that level of phalates and
the new material could be enough to lead to a failure also is the equipment
that's being used and they've run phalates and they've been properly
cleaned essentially you need to break down and look at every step are you sure
that every step of the way is there's no way that contamination can come in to
this issue and finally a lot of our suggestions and
emphasis is on qualitative analysis by technical staff and I'll be going into
this more but we have a few key points here we are CPSC method calls for a
retention time match with a standard phalates so make sure when you're
looking at the chromatogram and the chromatogram of a sample a retention
time must match or else that should be a red flag also a mass spectrum match this
and not just a general mass spectrum but the iron ratio is very important and can
help in identifying blank analysis is crucial for looking for contamination
within the lab result itself if you run a blank and you're seeing phalates in
there that means you have contamination along somewhere along the line if people
are reusing glassware we found in our lab that our GCMs Inlet liner sometimes
can carry these fat lights over so it's they're persistent enough that they can
come along the line even within the lab and I mentioned before the ein P and D
IDP have multiple caste numbers if you look closely new and you get standards
of both you'll see there chromatogram peak shape is a little different so this
is a great way to identify which material you're working for and you
should be if you're quantifying one specific caste number of di MP or di DP
your standard should be that same caste number so you get a fully well developed
match so I'll just give you a few examples of why a strong qualitative
assessment I'll help here I have two chromatograms one is of di NP and the
other is of a common Fallot alternative din CH if you're looking at the peak
shape they mostly look the same if you're looking specifically at peaks and
valleys you can kind of tell they're a little different but our experience and
I can see this translating to other labs is if you have a sort of an automated
quantification procedure where the computer will sort of do the work for
you if it's looking for a broad peak in this time range it may not know the
difference between the InP and di di n CH so here this is where
mass spectrum look can really illusi eight the differences the Dench base ion
is 155 vs di NP which is 149 so all really takes is a quick look at the mass
spectrum and you'll be able to tell the difference
another issue we've run into is DN o P vs. dioctyl terephthalate another common
alternative here I have chromatograms of the two of those you can see the
retention time is awfully close 11.15 minutes versus eleven point 100 minutes
and here I've noticed that our our previous settings for our computer
quantification program if the tolerances are empty enough or are wide enough
sorry it may not be able to tell the difference especially since their math
spectrum is pretty similar if you're looking if you're running a sim scan and
looking at the typical DN o P Mass ions do T P covers those as well but if you
do if you're thorough and follow through with your qualitative assessment you'll
see here's our DN o P a typical mass spectrum they speak again is 149 there's
a little bit of 167 and 279 mass ions we'll compare that directly with do T P
and here you can see the the jump and the 261 ion it's almost 50% relative to
149 so if you're looking if you're again if you're doing an automated program you
might get a false positive here if you had do T P so okay so we'll start to
shift into the the rest of the talk here or the rest of the symposium with the
discussion about emerging technologies we'll have a block of speakers today
discussing portable spectroscopy we've started using this as a valley screening
tool a general kind of yes or no might this item have phalates it's when this
law was passed people commonly asked well what's the XRF i'll so if we're
looking for an X or F for lead what's the fal 8 comparable option we have and
this is so far the most promising technology also I'll refer you to this a
paper by Zhang at all last year from chemical communications they developed a
colorimetric test it's a different application they're looking for phalates
in water but I imagine with the right ingenuity and the right research this
might be adapted for toys or childcare articles they use modified gold
nanoparticles that actually changed color and water when my lights were
present and also we're big fans of direct analysis in real time mass
spectrometry I will have a talk on that later so I won't steal too much of that
thunder but it's promising for a screening tool and we think with the
right research possibly also qualification method so just a couple
more sources for information we have CPSC has its own phalates website where
you can get information common questions also we have a lab frequently asked
questions page there if you're interested more in the chronic hazard
advisory panel there's also a website for that they should be issuing a ruling
I believe in that within the calendar year there's currently an ASTM workgroup
focused simply on phalion analysis for low level percentages so I have this
information here and finally EPA has a design for an Environment Program and
they're looking at alternatives to phalates
generally the idea is anyone that's interested in the valley realm and
they're interested in alternatives they can propose alternatives I think they'll
be looking at some toxicology issues so any company that's looking to move this
might be a good website to follow and with that I'll take any questions yeah
oh so he asks what NIST is this is the National Institute for Standards and
Technology yes we consider screening just essentially a tool or a method to
kind of give you a generic yes-or-no answer if phalates are present when we
look as a screening tool for if we're looking for lead we use x-ray
fluorescence as a screening tool this will give us like essentially 30 seconds
to a minute we have a general idea of if light is present or there so that's sort
of the itinerary we're looking for with valleys he asked if there's a acceptable
level for screening as far as false positives or not I think that's to be
determined you know we're trying to work with its each technology will have its
own limitations and you know I think the best we can get on any regards will
we'll work with for now I mean for a generic tool if you know are the limits
0.1% and I think for a final screening tool it will be able to it'll need to be
able to reach that but there might be different ways to adapt back technology
or different applications to try and use that to your best advantage hi I'm Joel
rectum the chemistry division director here I just wanted to add to that the
the what's needed from a screening tool depends somewhat on what it's being used
for as well so affirm we have a speaker here from BASF today BASF produces
phthalates there need to screen for four products you know for perhaps impurities
in their line are different than the needs that we have as a regulatory
agency or a manufacturer who might look to do screening in between their full
tests so you know there can still be room for for these screening methods
where it makes sense in a particular end use
I'm sorry oh yeah we we consider screen printing applicable to regulation yes
well I think we're we'd like to work towards that point it would be ideal but
we don't think it's at that point yet
yeah we think they've been used for oh I'm sorry has do TPD a little
terephthalate been in use often yes we we have we've we're familiar with it we
think it's been used and used for a while
that's not my I'm not I can't answer that that that would be a good question
for the EPA design for alternatives and and the chronic hazard advisory panel
all right great why don't we move along our next speaker is Raphael Costa from
Agilent
thank you thank you Matt for inviting me here to
this symposium is very exciting for us to be here and what I'm gonna do today
is share with you some of the different mass spectrometry techniques that may
aid you in solving that problem of contamination or library matching or
retention times matching up what are some of the tools that we could use and
what are some of the applications that admins are our scientists in the field
have developed to meet this growing need of phthalates and consumer products and
specific in toys and in particular so I'll go through some of the GCMs
portfolio the different technologies of different flavors of mass spectrometry
that could aid you in identifying phthalates in a way that gives you that
much more confidence in your lab I'll go throughout the application notes
developed by our scientist in the field and then we'll go through some of the
ongoing work that we internally at Agilent are working with to solve this
problem of trying to reach the levels required and the different technologies
and level of confidence in your results so for example the Agilent GCMs our
portfolio includes not only single quartz ion traps mobile mass
spectrometers as well as high-end triple quads and now cute off technology for
mass spectrometry what I will do is I'll say how each of these different
techniques apply to your particular analysis what are some of the extra
information that you get from each individual technique so for example we
know we have here the usual suspects of the phthalates of interest but their
caste number their molecular weights and there are corresponding ions for sim
analysis the typical GC conditions that was used in this particular application
was a very mirror column 0.25 0.25 micron db5 ultra inner column that this
will allow allow you to have more the ultra nurnies allows you to have more
runs per sample let's bleed in your chromatograms since
our mass specs are very sensitive there is a split ratio of 20 to 1 to avoid
contamination and column overload carrier gases helium
however we're noticing that customers are asking us hey can we use hydrogen
for analysis and that's something that you definitely can't do with your single
quads GCMs however we're trying to see how that could aid you more but the cost
of helium as you may or may not know is going up drastically recently and we're
trying to address that in terms of uh how can we take advantage of the
properties of hydrogen as carrier gas which is not a new thing in Europe they
currently use that's the carrier gas of choice hope
and we're trying to make our us customers aware of this as well not only
do you get the benefits of maybe having a reducing your cost of analysis by
having hydrogen through a hydrogen generator in your lab but also have
faster chromatography so we definitely want to ensure that you're aware of
though of that the possibility that that could bring to your labs well for
example here we have a total iron chromatogram of a pacifier extract on
spiked and spiked with two parts per million phthalic mixture on top you see
the mutilated hydroxy toluene as the main peak in the pacifier however when
we spiked it at 2 ppm we're still able to see this in matrix uh very nicely so
again not the DI MP and the DI p di DP are very uh a little bit less sensitive
to particular analysis of VII however there are things that that are mentioned
throughout my presentation that may allow you to see higher levels of these
particular compás and we'll go through that as well okay so for example you're
talking about sample cleanup and contamination one possible way to avoid
contamination may be to use the SPME or solid phase microextraction in your
analysis which reduces some of the the non analytes of interest of all the
matrix of your particular toys or analysis that would allow you to have
cleaner chromatograms and less contamination and more throughput per
samples went through GCMs okay so for example so these for these particular
compounds of interest these phthalates of interest we are able to regional of
in the level of from 0.25 milligrams per litre to 10
with a linear dynamic range and we have individual retention times for these so
we could definitely identify them not only based on retention time but also on
their spectrum as well with the GCMs one of the things that you may be that you
may have is if you're doing high throughput analysis in your lab and you
want to ensure have one method through all your lab you want to ensure that you
implore something that we call retention time locking how many of you are used
GCMs for analysis of valets today in your labs how many of you have an
Agilent system in your lab and how many of you are using retention time locking
and your instruments so that each retention time in each instrument that
you have with the same method is exactly the same one okay I'll talk through that
I'll go through that in my presentation and how that could aid you and having
that much more confidence it's one of the hidden secrets that we have and we
love my job here today is to make you aware of these features that may make
your life a little easier in the lab when you're analyzing phthalates or
other compounds of interest as well okay so I'll go here up so for example let's
say you want to take yours your lab method and you want to take it in the
field in the back of a mobile lab and you want to test at the point of sale of
our particular product you could do that with our agilent of 50 975 t for
transportable which implores LTM technology essentially what you have now
here is you have the same mass spectrometer that you're used to in your
lab and you're able to take it in the field at 1/3 of the footprint and half
the power consumption you could run it in as part of a mobile lab if you're
looking for phalates in the field for example and essentially as I mentioned
before the otm technology what it does is is essentially by heated oven so
essentially your capillary column is inductively coupled with a heater that
allows the maximum a lot of heat transfer very efficient efficiently so
now you have faster heating and cooling times so your chromatography males will
also improve you have more sample throughput now chromatograms that will
take you 20 to 25 minutes for analysis may take you five or less minutes for
the same analysis and still having the same
resolution and sensitivity so again that's that's something for you if
you're not aware of for you to think about if you're thinking about doing
mobile lab applications of phthalates in the field okay so one of the things that
they imagined that we that we recently were excited about is the introduction
of ion trap technology for GCMs and one of the benefits that you receive with
ion trap technologies the ability to do multiple I announced a ssin techniques
within the same chromatogram so for example for an ion for particular
phthalates that may not be as responsive to e.i analysis you could do a CI and
Alice chemical ionic station on the same compound in the same run in same
chromatogram so you can switch from e-i to CI without changing the source in the
same run which will allow you greater sensitivity and specificity for analytes
of interest and I'll show a particular example of that in this case we have a
VI MP and the IPP the IDP and we have them in AI and CI if you notice the e I
expect from shows the classical Mass 149 s as the after parent peak however if we
use CI with MTBE liquid MTBE were able to differentiate the two now base you
see have the molecular ion be the parent peak and now we have 419 and for 47 okay
the molecular ions in a higher intensity so if this is something that there may
be interest of you for you to identify the two you have the flexibility of
doing CI a liquid CI with MTBE to allow you to differentiate those two and give
you that much more degrees of confidence okay and again this is coupled to the
same 7890 GCC pneumatics are you used to on the front end just a different
ionization technique iron trap technology on the back end okay so here
for example in terms of calibration curve for bbp and VBP able to go down to
levels of one parts per billion or less okay so now we mentioned the other
labor of mass spectrometer that can be applied to the fellows analysis involves
the use of a triple quadrupole GCMs and I go briefly into how that operates
currently in our lab in and Santa Clara are one of our applications our chemists
and in conjunction with dois we're frontier we have a paralyzer system and
you might hear some of that today but essentially we're analyzing phthalates
using triple quadruple GCMs and that gives us a different degrees of
confidence and also lower sensitivity and there's an application now coming
soon with that information but I talked briefly of some of the preliminary
results that we that we have obtained so let me give you a little brief overview
of how triple quadrupole GCMs operates from for example you have your typical
spectrum so you ionize your samples they give you any I mode in this particular
example you get a classical spectrum okay everything is ionized broken down
into individual components however through the first quadrupole we isolate
one ion in this case we select the most intense ion which is 210 we'll select
that ion in this particular case and your Simenon die on that iron you pass
it that iron through a collision cell hit it with some energy and some
collision gases you're able to break down that ion even further into two
individual components and then you can monitor multiple ions from that
secondary fragmentation in this case will be a transition of for example to
10 go into 158 and 191 which may give you that much more fragmentation and
identification for some of the trouble and lights of interest okay so in this
case we have a mrm chink thick total iron chromatogram in of phthalates and
lemon oil okay this is this is the mrm take the e i spectra of the NOP and the
triple quad and you can see that the iron ratios are very similar to your
nest libraries that you're used to and we have developed transition we have
developed mrm translation multiple reaction monitored transaction for our
different values of interest where now if you're interested in having more
information on your salads and in that one particular ion with some
energy and a collision flow you're able to get to individual transitions one for
quantitation and one for quality ssin and you're able to develop a set up find
ratios for each particular transition therefore the ohmmeter particular
requirements for your quantitation this decreases your for your false positives
was met what it's talking about about false positives being a big problem
ms/ms could potentially solve that for you
reduces the amount of false positives in your thallus analysis okay now for for
higher quality data and for more interesting results for example you
could take the power of Q Tov mass accuracy and high resolution for the
analysis of valleys in high matrix you have the ability to do ms/ms and E I as
well and in this case what we have is our traditional triple quad which is
based on your single quad mass spectrometer that you used to currently
use it in your lab we took that technology a step further and
incorporated our trouble quadrant mass spectrometer to our tough mass
spectrometer that we have in our we had in our LC world that we made this
marriage of a cute off so now you have the ability of doing full scan high
resolution high mass accuracy less than 5 ppm mass accuracy and you know I'll
show you what that gives you what level of information that provides you in a
second so for example if you're used to looking at your typical single quad mass
spectrometer and we'll look at Matt's mass 604 what you see in the red is your
typical spectrum however it with the tough technology you're able to really
resolve the 613 and the 614 the 649 and you get accurate masses to the point
that you have more resolution and when we talk about resolution we're talking
about the space between the two the two different isotopes there let you see
okay so that's one level of confidence that will also decrease your false
positive or negative so if you have a high matrix and things that may be
interfering q top technology with the high- accuracy and resolution may give
you that extra level of confidence of able to seize the needle in the haystack
a little bit better okay so for example your typical mass spectrometer has a has
a insurgency let's say 0.3 a.m. use and for mass 271 for 9:00 8:00 a.m. you
there are 7600 compounds that are possible based on that mass insurgency
of 1000 ppm as the as the young certainty decreases let's say to a level
of 1 ppm parts per million now you have 11 possible compounds that are possible
with that particular ion of interest so that's where the again reduces your
false positives or high level of degree of confidence in your analysis also too
so those of you that are using our our mass spectrometers for the analysis of
phthalates retention time locking is very important and as Matt discussed
earlier retention time is one of the requirements for for the methods of
analysis having retention time locking allows you to have one method on one
mass spectrometer transfer that method to a second mass spectrometer and
they'll have the exact retention time okay
and whether you perform current maintenance or not you're able to just
we lock the method it's very simple to do it just takes five injection you
could do it overnight or over a lunch break
or right you can do it actually while you are commissioning your instruments
for analysis doing your performance check you take one analyte of interest
you look for that ion what it does is retention time locking what it does it
incorporates all the possible variations in column length pressure or whether you
have a difference of a few millimeters going into the inlet or not it takes all
the possible errors incorporates them into a pressure error and allows you to
match your retention times with fermented transfer okay so in any system
across this so you have a lab and the East Coast the west coast the retention
times will be the same if we're trying to match the new phthalates analytes of
interest so that's yes you have a question
that within the same historian if you were to replace a Kabul say could you
pull the data up and then switch out the column and then run that software runs
and then have yes yes you can do that while you change
count that retention time if you want the IP to be at 11 minutes 11 point oo 1
minute it will be at 11.1 minutes in this
instrument and that instrument will you change your column every day all day
year after year and it's free is included in your mouth and your camp
station software it's a button if you go in your method there will be an option
instrument retention time lock and I'll ask you to put a violin in a particular
position position one it'll do five runs at five different pressures and they
don't make a calibration of pressure versus retention time and then will
retain that calibration file and then you're able to your mentor will be
locked to a particular compound so if you want to lock whether on your
internal standard or whatever it is you can lock in your internal standard and
there was those retention times will match that way you won't have to
question it this style aid or is it that valid no because it's retention times
will match all day every day okay again and retention time lock and it's
available everything from from our 7059 75e single quad to our cubes off okay
even to your mobile lab if you want to retention time in your mobile lab you
have that flexibility so again one of things I want to emphasize this and the
other speakers will go into different other front ends that that made you an
analysis but I wanted to focus in the different capabilities is the take-home
message here is that if you're looking for routine analysis and you want to do
next and this is the convolution our single quad will be do a great job if
you haven't promised with hi matrix interference then there's that's when a
triple quad may be more suitable for the analysis because we'll give you that mrm
transition of one iron going through different transitions with two different
iron ratios so you get more degrees of confidence and if going from E AI to CI
is something that you really want to do for your analysis to give you that peace
of mind and give you that much more confidence in your results that's when
an iron trap with like liquid CI what MTBE may may aid you even more I just
wanna the references up you can look these up in our application notes and
there's more to come especially specifically on the cubes off
and the triple quad analysis and I want to give a special thanks to our
scientists that have worked on this Stefan Bowman fred fighter herm robert
kubis and matt thank you for inviting us to be here today
any questions yes
yes oh yes the question was whether we could use a ammonia CI reagent ah for
the analysis of phthalates and the answer is yes you can in this particular
case I was MTBE was used for through the analysis but you could definitely use
ammonia or even methane of that which but ammonia temps tends to be more
sensitive in terms of CI from what we've seen in particular for phthalates yes
good question any any other questions yes
thus we tension time lock work for multiple analytes the answer is yes what
we tension time locking does is it takes one particular analyte and typically in
the middle of your chromatogram so you pick whatever analytes and your lock on
that and everything else is gonna be relative to that so if you if this
analyte match everything else should match depending then you have a good
column in your column is now bad so yes so all the components will be retention
time locked but you only like a want to compound everything else is relative
what broader Peaks retention time locking what is gonna do is you're still
gonna have that broad peak however that broad peak will be at the same time so
that doesn't say essentially what's gonna happen it's gonna add your your
your chromatography in terms of resolution but it will give you that
same time for that blob of gram that you have for the InP yes good question yes
another question
okay the question is is our triple Quadra trapping or ions and the answer
is it's not really trap it is scanning scanning very fast and it's taking a
selectively passing ions that we select that we want so for example in this
particular example that I showed let's say you want to isolate 149 I've won a
and 149 will go through the quad it'll reach a collision cell once it reaches
the collision cell it will be hit with a particular energy typically between ten
and fifteen volts electron volt and a collision gas and from there we'll have
two different transitions that we can monitor typically the most the two
strongest transitions to give you that much more of degrees of confidence
the question was where is there any gain-of-function automatic gain function
the answer is there is no automatic gain however for compounds of interest you
could adjust the gains in the different time segments so for example for
analytes that are maybe less sensitive you may adjust the gain at that
particular moment in time thank you so much up next we have Bob Freeman from
frontier labs all right good morning I'd like to thank Matt for the opportunity
to talk about the method it's been in development now for about two or three
years about about three years ago we started at the ASTM D 20 former
committee to look at low-level phthalates in polyvinyl chloride and for
the past two or three years this is what we focused on we've done two sets of
round-robin samples and we've done independent validation study with some
laboratories so I'd like to give you just a status report on where that
method is give you a little bit of data and then I'll also like to kind of
address the issue of phthalates in hold because you'll notice that for those
people who do work on methods phthalates our particular problem because the fact
is that the method no longer is what what it was designed to do we started
off with toys and we started off with six phthalates and in the last two or
three years now all of a sudden we're looking at electronic products we're
looking at food containers we're looking at a whole variety of different matrices
and you'll notice that we've gone from six phthalates till now there's interest
in more than six in some cases fifteen and sixteen phthalates so whereas we
started with toys and consumer products now we have to work the stakeholders
include formulators past recyclers manufacturers retailers consumers all of
a sudden everybody's interested in phthalates and what we find out is
interesting that lights all over the world and this is all well and good
except for now you notice that the list is starting to expand a little bit and
so some of the electronics News have included things like dye
isobutyl phthalates which is a which is a plasticizer that's
not too not too uncommon it's a low-cost replacement for DBP so now we've gone
from from three regulated phthalates to a possible six phthalates seventh a
lates and you can see we're having the typical encounter here and that is as we
develop the method we officer may include more and more matrices and as we
do that we want more and more compounds and as we do that of course we want more
and more sensitivity and so those of us are workout methods this is a continuing
problem there's even there's even individual countries that are writing
general methods that have promulgated these most of them in 2011 and these are
just mentioning things like all products containing phthalates I mean that's a
pretty general description for method to address and because now you hear more
and more about the countries not being important the global global
international corporations really being the boundaries there are many
corporations that work on a global scale and have their own in-house methods and
in-house list of compounds and in Houston Texas and limits for various
number of phthalates and so these are just some of the electronics companies
that we know I'm familiar with that are working on phthalates in recycled
plastics and different lists and we work on right now so we've gone from in the
beginning the ASTM method is PVC and six compounds so now we're talking about
maybe fifteen or sixteen and way beyond PVC so let me back up a little bit talk
about the ASTM methods we're looking for a standard practice
for the determination of low level phthalates and polyvinyl chloride and
the method that seems to give us the best results this thermal desorption GC
mass spec so there's really five steps in this method and this is the most
difficult step to step right here called sample homogeneity because when you take
a toy for example different parts of that toy are made of four different
plastics and each of those different parts of plastics can have a different
level of phthalates and so I would say if I if I were to look at the overall
scope of analyzing for phthalates in materials the biggest problem is a
homogeneous because if I take this toy apart I can
get three different numbers some of them are good and some of them are a little
bit higher a circuit board forces the same problem a food container proposes
the same problem and so on and so forth so this is the single most difficult
thing to do and that is to get a homogeneous sample that sounds nice to
say crowd milling you go into laboratories that do crowd milling and
contamination crosstalk between Crowell Mills is ever-present and so one of the
problems with phthalates as we as we mentioned here is contamination well
right off the bat if you're using one crowd milled into five toys the
possibility for cross-contamination is very high this is the toughest step but
the method that the the thumb of the ASTM method for based on thermal
desorption GC mass spec uses two solutions one is just a standard
solution of the phthalates of interest and the other is the sample itself which
is dissolved in tetrahydrofuran so this is the there's only two solutions
involved the injection is simply placing these solutions in a small container
raising the temperature the containers such that the target compounds evolve or
make out or externally extracted and analyzing just that portion of the
sample that contains the phthalates separation is done by a standard 30
meter db5 or 5% phenol column and detector you can pick up most of the
work we've been done has been done with scanning ms several of the validation
labs used si MMS you can use quadruple crippled quads you can use negative ion
CI this is the area where the method seems to be the most applicable and that
is this is this is unlike the first talk this is how to get the sampler prepared
and how to get the sample into the column okay what column you use is up to
you it's independent of the column choice what sort of detection algorithm
system you want to use this up to you so this is the sample prep the whole idea
here is to give her the solvent to get rid of the glassware
because I've gone into laboratories and who do this and they'll tell me
oftentimes they spend more time cleaning Sox lists and using Sox's your salads
are difficult to get rid of and so what we do here is we start off
with the product some sort of material could be a circuit board could be a duct
we all like ducts you Crowl millet you want the smallest pieces you can if
possible you want dust because you want a homogeneous bottle of dust you take a
small portion of that and put it in a volumetric as a ten milliliter
volumetric so now you've got so much weight you add to that THF you make a
solution now so now you have a solution a THF solution of your sample the method
calls for taking ten microliters of that put it in a small cup and evaporating a
solvent such that you win with a very thin film of the sample on the inside
surface of the cup at the bottom so to prepare a sample like this once the
crowd millings been done to prepare a sample like this takes on the order of
five minutes they only solve what you're going to use
as 10 milliliters of the THF you're going to use disposable glassware so
there's no worry about contamination or cross-contamination that little cup then
is ready to be analyzed now if you wanted to do a screening method it's not
necessary to go through the thin film process and that is you can take this
sample dust from your jar and just weigh in a hundred micrograms or 200
micrograms and put it directly in the cup so you analyze it as a solid if
you'd like that internal standard at that point right now just a monitor
performance that's easily done so either way you end up with the cup that's ready
to analyze now the difference between a thin film that just making a THF
solution put it on the cup and then evaporating the solvent and using the
solid material is basically reflected in the precision so if I use a THF solution
this is a half a milligram of sample now you can see for this de HB the percent
relative standard deviation is about one percent for injections if I use the
solid form for a screening method where I just take the dust if you will five
point five milligrams of dust to put in the cup and analyze it directly you can
see my precision goes down and of course the reason for that is is if I look at
this this collections best that I have the chances of having the same amount of
particles in each sample remote so I give it a more scatter than the data
where if I make up a solution I can analyze that same solution numerous
times and get exactly the same but for a screening technique that the
solid analysis seems to work just fine can we hope to the end here thank you
so a sample assistant a little cup this is on top of a liner - maple injection I
dropped the cup in the furnace the furnace is at 100 degrees I hate the
furnace 200 320 degrees and as I heat it up the phthalates will evolve and those
are carried on to the column these little cups are can replace a lot of
stuff but I can do a number of samples now one sample per hour the reason for
that is is because the calibration the quantitation is done by a standard
addition that requires two analysis one of the sample and one of the samples has
been spiked with a known amount so that's to analysis so by about one an
hour if you're going to do a screening sample that means one I don't have to
program from one two three twenty I just drop it into three twenty so I don't
have that 11 minute to feel real sample prep for extraction simple and then I
could do about three per hour in the screening mode so the sample is heated I
thermally extract the phthalates of interest they go on to the column and I
get my chromatogram the conditions I'm using for my survey motor basically 100
to 700 at a fairly high rate that could allow me to profile a characterize the
sample and it tells me where the phthalates come in the temperature zone
of which the phthalates evolve and then I do my thermal desorption my thermal
desorption basically is 100 to 320 at 20 degrees a minute if you use in a thin
film you can do it 40 degrees a minute rigea moment much difference this goes
on to a column at 80 degrees so here's what it looks like the top traces by
screen I don't have to do the screening for every sample the importance of the
screen is it characterizes the sample if I'm doing PVCs forever I only have to do
this once if I'm doing polypropylene I only have to do it once but if I'm doing
circuit boards or if I'm doing different kinds of materials then maybe I have to
do my screen to find out where my if my phthalates have shifted but you can see
if I'm the top trace this is this a PVC sampled inch as a plasticizer I get a
large group of compounds out fester phthalates any
dents may be present there's also a peak for HCl because that's the decomposition
product of polyvinyl chloride and then of course I get my fractions out there
right polymerized or I realize the PVC so I find my zone by looking at ions and
you can see the lower trace where it says phthalates 149 you can see all the
149 all my phthalates are out by 320 and so my thermal desorption zone is 100 to
320 at 20 degrees a minute it's a nice thing about this is by doing this I'm
going to extract those phthalates and put those on the columns for separation
but I leave behind in the cup all the polymer so I don't have to worry about
faking the pulp making the system system at the cleanup the polymer I don't have
to worry about contamination of my system as I backflash or for the polymer
just stays in the cup of when I'm done I watched a polymer out and reuse the cup
or get a new cup all I'm going to inject under the GC is just that fracks of a
sample that's extracted at 320 degrees
so I can identify different compounds by ions this right here again this is just
your standard this is probably more interesting right here this is the
reproducibility this is 6 injections of a PVC dense sample and it's a little
hard to read but what I have here is this percent relative standard deviation
of the precision of a multiple runs of the same sample and you can see the
precision across the board is less than less than 2% so I can take one solution
and analyze the six times and my precision is pretty darn good
remember I mentioned that this is a standard addition method so I'm going to
run my sample and get an area number for my compound and then I'm going to spike
the sample with a known amount in this case point one five percent
concentration and going to rerun the sample so this is just the spiked sample
I just show three of these right here so this is the PVC dense sample where
that's been spiked with a known amount of each of the phthalates and again you
can see the precision across the bottom of the spiked numbers again less than 2%
so it's very precise I end up with a series of curves like
this so these are the six calibration curves for the six compounds the one in
the middle is that the zero that's the sample number the one on the far right
that's the spike number and there's a meth Max or go through and I can
calculate the amount of amount of pieces of phthalates in the original sample and
if you do that again you can see the precision there is less than 2% and it's
a little hard to read but the numbers the concentration of this of each tally
that this particular one was about 980 990 nanograms so the accuracy is pretty
good now that you see it korea is also interested in this method this is some
of their work these are their six calibration curves only in this case
they spiked with three mount three different levels and all you do is take
that one solution and you can see from your upper right trace one case you put
two microliters the next case three microliters the next case 5 microliters
x8 merica there's that's how you get you multiple points so it's still one
solution and you can see their recoveries are of all the six phthalates
are pretty good and their precision is also less than one one percent in this
case now we didn't mess the salvation study that is we've been out to found
five laboratories who are willing to try this these as laboratories that hadn't
done this before in one case one of the laboratories had a new higher to that to
the study force and this is this is what we found from the validation study
I sent them four samples to them with the same sample the thermal desorption
temperature system dependent by that I mean if you have a factory system or a
Pvt in the system or a CVS system or a Gerstel system whatever system you're
using for your thermal desorption you have to be very sure that what you're
looking at is the sample temperature or not the thermocouple temperature so
there's some differences in some systems between the set point and the actual
point how you ready to do is run the the EGA and you can determine the
temperature range of a which that system operates best some of the validation
labs you sim some of the validation labs you scan it both to produce comparable
data thin photo columns are definitely preferred over thick film columns we
don't a lot of retention and a whole lot of
time in there the standard edition everyone use standard edition at one
point standard edition the r-squared was always greater than 0.99 if you if you
recalled back to this study this is this is three points plus the sample in the R
squares and all these are one but these five laboratories all data point nine
nine are better the inner lab injection to Jackson reproducibility is less than
five percent the data I've shown here is all about two percent one of my five
labs with the newbie they were they were about thirty percent higher than
everybody else in the whole wide world so there was some systematic issue there
but I included all their data that's how it comes out to be five percent the
inter lab sample the sample reproducibility is always less than ten
percent and the laboratory laboratory accuracy is 25 percent now get if I take
out the data from that one lab and drop down to about ten percent but I can't
find a reason to do that so these are the numbers we came up with from the
validation study of these five laboratories now all of a sudden we're
getting requests for an extended target compound list so here's the extended
target compound this we've been asked to look at next is this method I've
highlighted in red the six compounds we started with in order to do this
chromatic graphically it's a simple thing he just dropped the initial
temperature from 100 to 80 degrees and he tried to do a little bit better
separation on that front end better stow your host that only goes up to D ID P so
it doesn't go any further so the analysis time is still on the order of
about twenty minutes so it has already lengthen your analysis time and since
your sample prep time is baking up a ten microliters 10 milliliter solution of
THF it's it doesn't affect any of your sample prep and your operational
parameters so it looks that was like it's almost too good to be true we've
done this for three years the TD method is easy it takes one syringe and a
little bit of glassware it's clean there's no cleaning the cleaning and
cleaning and cleaning and socks with extractors that sort of thing it's great
because I'm using almost no solvent at all and it's fully automated that sounds
really really good it's precise and accurate the precision is always less
than 2% the accuracy is plus or minus 10% in your laboratory and it
accommodates an extended come down list so this is all well and good there is a
downside though the downside is this run to run
contamination issue was a real problem the and thousand for millions that not
too much of an issue that's bucket chemistry but as the as the detection as
the sensitivity requirements get higher and higher more and more sensitivity we
have to wait find a way to really monitor this contamination the
contamination is in the injection port there's no doubt about it
also the quantiles would have to be verified as we change matrices that's
one thing to look at PVC which is what the ASTM method was focused on and we
know appropriate probably propylene and probably either ethylene and we've done
a number of different polymers what happens with the circuit board what
happens with it some kind of material you haven't really looked at so you
really have to verify that you have no in no interference when you start
changing matrices and the second the third thing is when you deal with these
compounds that are isomeric mixtures like di DP the quantitation becomes a
little bit more difficult it could be I love my mother would kill me for saying
this it could be HPLC may be a better way to do these multiple these compounds
that have a lot of different isomers so in the end those of us that develop
methods are in the deep trouble here because now we've got them we've got a
method now that was developed for six compounds in PVC and we're asked to do
more and more phthalates and we're asked to do it more and more different
matrices remember being asked get lower and lower and higher
I guess higher and higher sensitivity and in the case of phthalates this could
be a real challenge for the laboratory any questions we have time for one or
two questions yes
that was our SD company yeah yeah that's what a half safer yes
yeah the question is is the precision accuracy depended upon of the cryogenic
billing of a sample all the work here was done with PVC standards that were
prepared by one of the members of the ASTM committee and so it wasn't
literally a sheet of PVC and so yes see now you're getting into legal issues
yeah I mean obviously you are as a citizen I think you are but as the the
methodology that we've familiar with it calls for a number for the entire
product and so yes you are diluting the beak but on the on the other end you
know how much the because of the duct you know what but that's the critical
issues at homogeneity sample homogeneity
just quickly to add on to that that we're really not here to talk about the
policy and the regulations but we have issued guidance that it's the component
parts that the thallus limit applies to so we're our very initial guidance was
different based on the initial read of the rule we have guided the individual
component parts but regardless of that then the analysis is still the same all
right
up next we have chrissteele from bureau veritas
you could just press forward or back or you can press one of these buttons
doesn't make sure you speak clear enough came back alright thanks Matt yes I'm
filling in for Lisa Clarissa a global technical consultant specialist because
she is there's a touch of a flu bug going spreading around at our Buffalo
office so hopefully I don't get it after after we leave to get back to Buffalo
but so I'm speaking on behalf of Jarrow Veritas in lieu of her so yes no problem
so thank you Matt for letting me represent our company here and I'm here
today to talk about using a dual instrumentation for phthalates analysis
and plastics and what I mean by that is two systems to mass spectrometers the
first of course GCMs has I think a lot of you are familiar with and that the
CPSC method revolves around but secondly the lc-ms system using both in
conjunction with each other just to kind of rule out any interferences that GCMs
may pose basically to get like a second set of eyes looking at a particular
sample scan bureau veritas his head about I'm guessing at least 10 years of
experience testing for phthalates in a variety of consumer products many
different plastics and I'm here to try to share with you hopefully some help
for helpful information that has worked for us in our testing approach to
resolve these tricky samples as we know as time goes on and regulations are
expanding manufacturers seem to be trying to get more and more clever as
trying to find workarounds to find alternatives plasticizer alternatives to
have their samples compliance so in effect you're going to we see it we see
a lot of different scans and our thalut extracts because of this because they're
using
alternatives sure sure sorry so that's that's my purpose here today is to try
to share with you our daily testing approach so just as a quick outline I'm
gonna go over the test method that we use the instrumentation that we use GCMs
and LCS LCMS of course results in interpretation and I'll answer try to
answer any questions you may have about our approach our test method extremely
similar to what's in CPSC essentially we cut the sample into very small pieces of
the component we place it to a disposable glass reaction vessel or vial
then we add tetrahydrofuran THF and sonicated at 40 degrees centigrade for
30 minutes which in most cases will be long enough and aggressive enough to get
that into the organic solution in Sonic 8 an additional 30 minutes if that
sample does not visibly dissolve sometimes that happens with harder
plastics after which acetyl nitrile is what we use acetyl nitrile ACN is that a
drop ice to precipitate off the polymer that's been very useful for us I know
other solvents and the CBC mentions hexane using hexane
other LEDs may be using methanol they may work in particular applications or
plastics PVC probably works but we've found that co nitrile will precipitate
out more polymer more types of polymers than the other solvents so in in the end
it results in a cleaner layer on top of your precipitated plasticizer a very
precipitated polymer so you're all that junk and interfering things that may
interfere what the analysis will come out of that solution and then you can
inject a much more clean solution into your instrument so once that is done
you'll have to stand for 30 minutes and take that solution and to put it into an
autosampler vial and it's ready for analysis actually ad if they're seeing
good rate of the unforeseen there's an internal standard then you can filter it
and analyze it by GCMs indoor lcms and currently LCMS is not listed in the cps
c method currently I will go most of you probably are already aware of the
function of gas chromatography you have a carrier gas usually helium the sample
is injected in the injector volatilized goes to the column the analyte separate
out from one another as well as any interfering compounds they separate out
from one another then it enters the mass spec detector fragmentation occurs a
mass spectrum is produced and the signal is plotted on the chromatogram okay what
we're looking at here is just an example of many different types of phthalates
that are out there obviously it's not a complete list but it's just it's just
here to demonstrate what we could potentially be looking at when we
analyze a particular sample extract any one of these or a combination of these
could be found in your sample so a lot of them are nice clean needle peaks of
course as mad as mention and many of you already know we have the broad finger
peak type sale lights to that a regulated di MPD IDP you can't see it
too much on this slide but you know it's it's buried in there between the 12 and
13 minute range so this is just to demonstrate what we could be looking at
in a sample and like I said this is not a complete with
by any means some of these are regulated some are not so go on to our next slide
this is just an example of a mass spectrum of DBP just as an example we go
back a slide DBP is just one that's highlighted as an example if we look at
the mass spectrum creating that response this is it
of course they speak 149 is very common qualifying ion could be 223 which is
unique to DBP now a GC mass spectrum of di NPD IDP those troublesome finger
peaks you could the InP would be 293 you could extract that out of the
chromatogram but even doing so it still can sometimes be a challenge depending
on what what you might have interfering with that I'm going to talk a little bit
more about that in the upcoming slides as well this is an example of a non
regulated daylight currently unregulated you never know what the future holds dye
ISO octal phthalates basically this is a finger peak as well this may be present
a sample you don't know what manufacturers are putting in we've
certainly seen it many times before in samples dye ISO octal phthalates it's a
it's like a couple covered carbon chains last of course then Diet di n P and D
IDP the nanos and decals so here you can see their retention time it's a range
it's a broad range it's it's in isomeric mix of course and that's why it looks
the way it does so you can see it spans across the time line retention time line
you know between like eleven point two five minutes to twelve and a half so is
if you see something like this in a sample it can be challenging to properly
integrate the regulated phthalates or even see if they're there di NPD IDP
even after ion extraction honing in on a particular ion that may be unique to
that particular Valley so here is an example of di MP on a GC chromatogram
highlighted there it's it's if you want to call that in a pax it's peeking out
around 13 minutes but the range of isomers begins at about 12 and a half
and extends out to like 13 and a half minutes so anyone doing a lead analysis
by GC this is second nature I'm sure see this all the time so again it's very
difficult to integrate and try to accurately capture the area counts of
that di e MP peak if you have other interferences or other phalates present
it just it can be challenging on the GC
so here we're just looking at some chemical structures of some regulated
thelet's we have d NOP di n p di DP d NOP is unbranched so that's it it's a
single peak but all three of these have roughly the same retention time on GC D
NOP is an octal di o P which I mentioned before is an ISO octal so you're going
to see 279 ion 279 even if you extract enough for DN o P if you have di o P in
your sample and what do you do you see this big under al unregulated 279 I in
chromatogram and then you may or may not see this little peak come out of da that
may or may not be DN o P if it is DN o P and you're confident it is okay now how
do you quantico annotate it it's very hard to baseline integrate when it's
coming out of a mess so di NP + di D P of course our isomeric
finger Peaks they actually overlap on GC even though they have quantifying their
qualifying ions associated with them they can be troublesome as well and of
course the reason that they are broad finger peaks is because I so know no di
NP and I sewed a co di DP have it could be a multiple of arrangements of the
groups on methyl groups they could be located in many different statistical
possibility and that's why you see that broad finger peak of course it's not
just a single analyte it's a mixture of isomers I'm sure you're all familiar
with why they look the way they do on GC
now let's get into lcms instrumentation liquid
chromatography coupled with a mass spectrometer pretty much basically the
same principles GCMs you're just using liquid is the mobile phase or carrier to
carry along your analytes they get separated by a column the same
renters spray chamber mobile phases evaporated fragmentation occurs and then
the resulting ions are separated out by mass to charge ratio and response is
created as well as a spectrum so this is an example this is a di NP at 1 ppm on
the LCMS so what we're looking at here is we run in scan mode this is actually
I in 419 I believe di NP and this is only 1 ppm we do run standards a little
bit lower than this but the point is you can see how much better it looks to a
chemist I mean this this I like the way it looks it's very integrated the
signal-to-noise ratio is very large it's just just a great responding signal for
VI NP it just jumps out of the baseline is it's it's great
di DP at 1 ppm similar similar look to it comes right out of the baseline you
know you get a much better response of course than compared to GC there's no
broad finger peaks and actually the IDP is fully resolved from di n p on the
lc-ms I'm sorry
yeah it's reverse phased yep and and this slide is just kind of giving you a
side-by-side a di NP in the upper right on the lc/ms di NP and the lower left
and the GCMs that you can see it's hard to see of course because di NP n GCMs
relative to the single analytes it just kind of it's not very responsive because
it's just a nice American mix so that's one advantage that we found with using
lc-ms is really for for those finger peaks so our approach like I said we use
both GCMs and lc-ms in conjunction with one another if the lab decides to use
GCMs primarily it's kind of a flow chart showing what should be done if you find
the family's DN o pd ID PDI NP they should be confirmed on lc-ms just just
to ensure a good quantitation and just to confirm that's out there now if
you're going to primarily use LCMS you can do that as well but then yet there's
things you need to know about that though if you find DB p dibutyl
phthalate which is regulated it also that well it will call a loop with an
unregulated thell a die isobutyl thely so if you're getting a detection on DB p
it may really be die isobutyl faily they they essentially Khoa loot with one
another so that's why if you do find DB p it's it's pretty recommended pretty
urgent that you confirm it by GCMs to see is it the regulated form of the
unregulated or a mixture of both and we've seen all three cases there so that
that's pretty much the flow that that we found to work for us
so in conclusion a dual instrument system works for us it's been a useful
approach enhancing our data integrity with challenging samples and like I said
before as time goes on we just just when you think you've seen it all you haven't
we've seen new plastic plastics come out with different compounds and adding new
challenges it's like an ongoing process the learning never ends so this is what
Bureau of our Bureau Bureau Veritas has found to work for us in our long history
of fail a testing in order to provide clear results from an otherwise messy
scan just because of this we feel much more confident and the data that we
issue basically we were having two detectors give us data if need be
it's also important to note that you don't need a state-of-the-art gc-ms or
lc/ms I mean you can use models that been around for years it's not like you
have to go out and buy the the most sensitive instrument to take this
approach on so that in that sense it helps labs that I'm looking for you know
cost savings of course so in the end it's all about just feeling confident
about the results and data that your lab is issuing with these tricky samples are
there any questions yes
yes the question was do our labs in Asia used the dual method approach I'm not
sure I from my understanding I know they they have both okay
my consultant they're saying yes they do I knew they had both instrumentations
but I just got confirmation that yes they do
the question was is this our standard practice in testing for di MP & di DP
yes it is yeah just because it's just so tricky on
GCMs we wouldn't just we just wouldn't feel that confident issuing results if
we get something that would really challenge the chromatography like we
often see on GCMs so yeah this this is our our good practice here bébé yep go
ahead
on LCMS sure actually I can go back that's fine um actually if we overlaid
them it show better but this is there are two separate identic stretches as
well this is a leaf for tickets for 19 I'm the LCMS you want to take a look at
this you know starting off it you know ten and a half going to twelve and here
we got twelve - like 14 for di DPL CMS total run time including the post run
and leave just 22 minutes something like that 24 minutes
yeah yep okay yeah we're involved in internal correlations with their own
company as well as external correlations to see if the methodologies that other
labs are using are comparable with ours so yeah that's that's part of our
quality control all right let's thank Chris thank you
up next we have Luke Ackerman from the FDA
thank you all for coming and thanks for organizing this okay okay so today I'm
going to be discussing dart MS or direct analysis in real time which is an
ambient ionization mass spectrometry technique as a possible screening method
for phthalates specifically we've been doing a lot of work on food-contact
polymers and looking for rapid screening techniques phthalates just happens to be
one of the model additives that we look at whenever we evaluate methodology so I
thought perhaps I could share a little bit of our work with you here and I
think just to kind of give you the conclusion I think dart can be used as a
very effective screening technique it has limited capabilities otherwise but
I'll be going over the details of that and I work at the Center for Food Safety
and applied nutrition at the FDA we're a research arm of the FDA so I'm not
conducting any regulatory enforcement actions at our facility we're developing
methodology and trying to advance the science at the agency so I won't be
discussing any legal matters either so how does dart work well dart is as I
said an ambient ionization technique it's just one commercial application of
many different you've probably heard of desi dart a sap gosh what else nano desi
supersonic electrospray ionisation these are all the academic terms for various
techniques of producing gas phase ions off of condensed materials so solids and
liquids and turning them into gas phase ions such that mass spectrometry can be
used to help analyze the stuff in question in this particular case dart is
unique and was probably granted a patent because it quenches a plasma it
generates a plasma of helium in the glow discharge area of the diagram here and
then it quenches them on the grounded electrodes in a further down stream it
then subsequently heat it heats that gas and the quenched plasma generates
excited helium or metastable helium which is just an electron shifted up in
energy level in the orbitals of helium once you heat this helium stream you now
have hot excited helium it exits the dart source and into the atmosphere of
the lab where you place your sample the atmosphere in the lab not surprisingly
contains water vapor and water has a good match with the energy of the
excited helium and it produces protonated water clusters and these
protonated water clusters in turn ionized any gas phase molecules in the
vicinity of the source there's been lots of studies on how big of a gap you need
and for different compounds different distances between the exit of the dart
and the entrance of the mass spectrometer will yield better results
but in general your protonating whatever gas phase ions you can get and the
thermal heating of the helium gas also allows thermal transfer to the surfaces
so you're doing thermal desorption so dart is thermal desorption atmospheric
chemical ionization similar to the negative and positive chemical
ionization possibilities with standard GCMs techniques but this is done in the
open lab atmosphere and the advantage of that is that allows you to stick odd
shaped objects in front of a mass spectrometer so you don't have to do
sample preparation in order to get some sort of representative spectra of the
surfaces of the samples that you're looking at as you can imagine that
creates a whole host of other questions as what kinds of surfaces how close what
compounds how hot those are all parameters that have to be dictated
according to each application but this is the basic approach that dart takes to
producing gas phase ions for mass spectrometry and what does Dart actually
look like in practice we've generated a little movie here one of the advantages
of dart is how fast it is and this will show you a mass spectrum of a little
sample that was introduced you probably maybe saw in an upper right hand corner
a little gap glass capillary came down and was stuck into the dart stream and
you see a peak there at M over Z one seven this was our demonstration of how
melamine is detected in milk products so we coated a little glass capillary with
a milk product and if there was melamine present it was Heian eyes dan M over Z
127 mass of melamine plus h or plus proton jumps up on the screen there and
you can see the time frame there is on the order of 30 seconds or less per
sample so you get an immediate spike in signal and it drops off rather quickly
as fast as your robot can go and pick up another sample or you can go grab
another sample it returns to baseline and you're ready for the next analysis
so what does dart m/s measure well it measures mass spectrum because it's dart
is just an ionization TKE technique for a mass spectrometer in this case we
interface dart with a Watters última which is just a simple triple quad and
we looked at the mass spectrum because of the way that we set up the dart and
because of the mass spec you can see a couple of diagnostic ions here for in
this case diethyl hexyl phthalates you see the molecular ion the n plus h some
of the characteristic fragment ions we were running this under some slightly
fragmenting conditions and if you use different mass spectrometers you get
different results so the bottom trace here is the mass spectrum of the same
standard using a Joel acute off which is just a low-end time-of-flight mass
spectrometer about 170 K for one of those and as you can see there even in
the presence of a mix standard this happened to have a little di n pol di DP
and some teh P you can see the dominant ion because of the chyme on the trace
that I picked was that well the octal phthalate I should say signal and the
nice thing about using a toss is of course the added mass accuracy as you
can see you get high mass accuracy M to a certain degree a good mass resolution
there's certainly other mass spectrometers that can achieve better
but the point being that when you're doing direct analysis or atmospheric is
analysis you're gonna get mixtures and you no longer are using chromatography
to help separate your chemicals previous to analysis so anything that you can do
to help you differentiate one molecule from another can help and accurate and
high res mass spec can help with that so what does the dart ms response look
like well you're not using chromatography so you don't have a
chromatogram now you just have a time trace this is a typical total ion
current it's not a total item chromatogram there's no chromatography
of a couple of sample introductions in front of a dart and in this case this is
from a triple quad the waters that I was mentioning and you see the TIC rise and
fall but rather noisily and rather air reproducibly but when you go to look at
a particular compound of interest you see that the trace is a lot more easy to
understand and in this case the the dhp standard of various concentrations gave
a very predictable response as a function of time so again we're looking
at a mass spectrum as a function of time so what are all the different dark
configurations that I've been discussing well we started off in our laboratory
with a first generation dart which is kind of a clunky looking thing and in
this particular case we are using a robotic auto sampler to place little
strips of particular polymers into the dart stream you'll see a little glass
capillary tube sticking out that helps transfer the gas stream from the
ionization region into the mass spectrometer and because the
manufacturer of the dart ion source had not interfaced this particular mass
spectrometer we literally just terminated the glass tube immediately
adjacent to the mass spectrometer Inlet it wasn't even on axis and so in that
case our sensitivity was quite poor and the results that we generate with this
configuration weren't really translatable to a lot of the people who
had purchased the Jol acute off switch was the parent company of the ion source
manufacturer dart is manufactured by iron sights
out of p body mass we subsequently purchased two other configurations at
dart Orbitrap in a dart a cute off so this is the joel a cute off and the
newest version of their dart source that goes with the a cute off again as you
can see here the the silver cone coming out of the mass spectrometer that's the
inlet the silver and white cones coming off the dart source the that's where the
gas exits we happen to be running a little homemade rail linear rail through
the dart source at this particular case we were mapping some chemical
concentrations across the surface of a piece of packaging and we just thought
we'd try a little linear rail in that particular case but as you can see the
dart source can be moved back and forth various distances from the mass
spectrometer Inlet they even have configurations that allow you to raise
and lower it angle it at different angles and so you really can adjust the
dart source to fit whatever geometries you need for your particular sand
samples the beautiful thing about dart is you can stick really crazy shaped
objects in front of it and you can still get reproducible mass spectrum you don't
have to mill you don't have to homogenize now you lose all that
information you lose reproducibility and quantitation and the like because you're
not looking at the same sample as you would with in in a typical regulatory
analysis but if you're going to screen stuff and if you want to have an idea of
what we're on a particular object phthalates or any other compound might
be for the surfaces of those objects then dart will allow you to to do that
by looking at only one part of the object at a time or if you're really
want to cover every surface you could systematically run the whole surface
through there but in either case dart is a quick way for a laboratory worker to
look at a sample without having to do prep and without cross-contamination
because there's nothing to contaminate here the entrance to the mass
spectrometer which is going to be less contaminated than if you inject a plug
of solvent from from a GC system so it's it's got some advantages that way
here's another angle us introducing a little piece of of packaging you can do
it manually you can use linear rails they've got transmission configurations
where you can deposit extracts onto little gridded wire meshes and the and
the helium flows through the wire mesh and dissolves whatever was on the
solution that deposited on the grid you know there's lots of configurations for
introducing samples via dart so can it quantitate that's the big question and
the answer is no so these are some just some straight-up
solvent calibration solutions and just measuring the peak height of the mass
effect signal for diethyl hexyl file a very simple task
not at all linear not very reproducible at that and the reason is is that
various amounts of materials are deposited onto the tip of the glass
capillary that we use to sample the liquids in GC you're using a syringe to
deliver exactly one microliter every single time whereas in dart the current
autosampler configuration dips a melting point capillary into your liquid
solution and depending on how clean that capillary is how far it's dipped in how
quickly you know what was there a drop shaken off the capillary in the robots
movements over to the dart you get various quantities deposited on the
surface and then how fast you scan it through there were there any air
disturbances in the lab that shifted gas flow patterns it desorbs a different
amount of material off of that and a different amount makes it into the mass
spec and a different ion signal but one way to account for all those differences
is internal standards you know in GCMs we often do that you get very nice
linear calibration curves when you internal standard normalize your
responses can also it also helps you with troubleshooting issues in your
methodology recovery correction you don't have to take you don't have to do
quantitative transfers all of those things are helped by internal standards
and so is dart calibration when you include just two internal standards in
this case for these suite of Leites that you see on the bottom right
I included a labeled standard of diethyl phthalate and a label of diethyl hexyl
phthalates and then normalized to one of those to the relative response is quite
linear and you know R Squared's that we go on about all better than 0.995 but
when you look at them on a log scale you see GCMs is still much more linear than
dark and that makes sense your just a lot more controlled sample
introduction a lot more controlled ion transfer into the inlet not to say that
it can't be useful you can't get good semi quantitative specially out of
liquid solutions but it's never going to be the same as GCMs and i would like to
point out this is over five orders of magnitude so clearly a very broad range
here and and but it's still GCMs is the gold standard for quantitation so it can
quantitate in solutions but we're not looking at solutions we're looking at
surfaces so how sensitive is dart when it comes to looking at surfaces well we
had another project where we were looking at photo initiators transferring
from the print side of a printed piece of food packaging to the food contact
side of an adjacent piece of food packaging it's called set-off and we
decided to look at err geekier 180 for a common photo initiator by producing
standard samples with various levels of the photo initiator on the surface of
the polymer this I believe was in LDPE film and what we saw was just some of
the concentrations of the samples that we prepared you can see that the
surficial concentrations at dart which dart is able to differentiate from the
blanks is right around 0.25 nanograms per square centimeter so definitely down
in the low fractions of a hundredths of a percent level you're going to see
surficial concentrations orders of magnitude higher if you're looking at
even 0.1% phthalates in a polymer so clearly it's
more than sensitive enough for these types of compounds we haven't done this
exact procedure with phthalates but the responsiveness of dart and area 2 of
dart to area cure and phthalates is very comparable they're both small molecules
I think this vapor pressure of this compound is almost exactly the same as
diethyl hexyl phthalates vapor pressure is a pretty big factor when you're
thermally desorbing something off of a surface so we see pretty comparable
responses in that case i expensed expect the sensitivity for phthalates to be
very comparable and then we also need the technique to identify the phthalates
and in particular the nice thing about dart as I showed you back at the
beginning is it produces almost exclusively molecular ion that is M plus
h you know one of the reasons why we like to use chemical ionization it's a
much softer ionization technique it doesn't give you as reproducible mass
spectrum on those fragment ions but it gives you a lot of very specific
molecular ion to work with you can also include a little ammonia hydroxide in in
the lab environment or swab it onto the surface of a polymer and you can produce
ammonia instead of protonated molecule ions so instead of m plus h SN + NH 4
it's often a common technique to look at both of those ions as a way of
confirming that you know the 195 iron you see is really corresponding to to
dimethyl phthalates or whatnot and as we all know this m plus h ion is very
useful the fragment ions help a little bit more but isomers produce all the
same ions in theory and they should because there i Cerner's they're
positional isomers so diethyl hexyl phthalates and octal phthalates are
perfect example and other work by other folks including Roth and Bakker and and
SH walk it published in rapid communication and mass spec took a close
look at this I think cooky out of Hungary also did the same thing in
international mass spec Journal and what they found is the 261 to 279 the the
Ethne minus ethylene and minus ethanol fragments are produced in differential
ratios and that really froze up and you can
differentiate ethyl hexlen and octal that way the trouble is a lot of things
can produce 261 and 279 and pretty much any isomeric octal phthalates can do
that to varying degrees and what if you have mixtures of these phthalates so
when we looked at a particular PP and LDPE film for various phthalates we see
the molecular ions of ethyl Hextall or an octal and also dye I so know no
phthalates when we look at the iron ratios of the fragments 279 clearly it
exceeds 261 suggesting it's ethyl hexo phthalates you know the ratio is 1.7 but
in the standards that ratio was 3.3 so what does this mean and in our initial
analysis of this sample which is the cookie bar at the bottom of the chart
there we said that we thought there's low hundreds of nanograms per square
centimeter of diethyl hexyl phthalates and we didn't think there was an octal
phthalates we then subjected these same samples to extraction LCMS analysis
here's the chromatogram and we focused a lot on that isononyl phthalates in that
particular case and what we saw was a very odd shape lcms peak we expect nice
sharp lcms Peaks for the ice and onal and we suspected it was an N octave
Dessel phthalates which would be a particular structural isomer of of the
no no phthalates and sure enough when we spiked it with an additional hundred ppb
of dinnah that small shoulder goes up so din up is the shoulder and n octave
Dessel phthalates was the dominant compound in this particular package
similar analysis of ethyl hexyl and an octal in this particular and compound
the cookie bar showed as you can see on the bottom that there was actually
nearly equivalent concentrations of an octal phthalates and ethyl hexyl
phthalates that's why our iron ratios of those fragments switched by dart ms and
we completely missed the anak the daesil phthalates in this particular sample so
what can we can conclude from all of this well sample positioning effects
dart response it's more than sensitive enough for phthalate
analysis it can be quantitative in certain situations when you use internal
standards and especially with solvents it can be sending semi-quantitative off
of polymer surfaces especially if you can deposit an internal standard which I
know some nist groups have been working on for the explosives methods they've
been working on printing standards on surfaces and it cannot reliably identify
different isomers of different phthalates not in mixtures and one last
note is the time responsive dart so this is a typical tick and this is what that
stand this is a total iron current of a typical standard for Dart and what you
see here is first the solvent ethyl hexyl phthalates or ethyl acetate excuse
me came off the surface of the of the tip and then the diethyl hexyl
phthalates in the last second and the time scales of these are about 1/6 to
1/9 of a second so you need to be measuring your your mass spectral traces
at 6 to 9 Hertz at least so cycles per second in order for dart to really be
useful in capturing the actual quantity law so these are all things that we need
to keep in mind but again the main points it cannot reliably identify the
different isomers it can quant under certain circumstances but it can
certainly screen for the presence of various phthalates thank you
well if you can reliably move the sample through the dart stream like we were
doing with that little linear rail on the surface then you can assign a
spatial map that will be our next publication where we reproduce the set
off image of a print on the adjacent piece of packaging you can see the same
trademark logos and you know images but just recreate it in a chemical map well
so the width of the of the dart beam is on the order of about a centimeter or
three-quarters of a centimeter somewhere around there I know that they're working
on different iterations that have narrower helium being widths but really
double or triple that and that's probably the double that and that's
probably the smallest scale of resolution you're going to achieve and
then of course you can screw it up by moving the sample too fast or you're
reproducibly yeah why don't we go ahead we'll break for lunch now and we'll
start back up again at one o'clock