April 18, 2024, 11:35:52 PM
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Topic: Analytical instrument - polymer characterisation & plastic-related chemicals  (Read 2709 times)

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Offline Amaark77

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Hello,
I've been trying to find out if it's possible to use only 1 instrument to detect both materials (common synthetic polymers such as PE, PP, PS) and toxic chemicals such as BPA, phthalates, PBDEs, PCBs, DDTs, etc in the same sample..
Do you maybe have any suggestions? I'm not a chemist and I'm struggling here. I've read so far that FTIR has been used for polymer characterisation and GCMS for plastic additives, POPs and other endocrine disrupting chemicals. But I'd like to know whether FTIR would be able to detect chemical compounds in traces in a sample of animal tissue, or if GCMS would be able to identify microplastic particles in a sample. I'm aware there are heaps of instruments out there and some are just slightly different, which makes my nightmare even worse.
Thanks for your help. And pls, be gentle on me! :-)
Cheers,
Amaark

Offline Arkcon

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Unlikely that it will work perfectly, but someone might do just what you suggest in limited cases.  You're not just asking for two diverse chemical classes, you're also looking at diverse sample types.  The traces of plasticizer compounds in animal tissue is too complex a sample -- given the interference from the tissues.  Generally, you'll want to digest it free, and analyze by GC, but then you're limited in the variety of reagents you can test for.

Similarly, particles of plastics can be analyzed on an FTIR with an ATR crystal with ease, but the traces of plasticizers would end up lost in the noise.

That's not to say that if someone wanted to know just one, they wouldn't try using the "incorrect" instrument, its just that any method they develop would be highly;y restricted in what they can detect.

By the by, why would you want to limit yourself to just one type of instrument?  Are you outfitting your own lab, or are you trying to write a script for a CSI-type story, wherein one instrument does very diverse tasks, in seconds, to perfect accuracy.  Preferably manned by a woman wearing impeccable designer clothes better suited for a night clubbing than for working in a lab?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Pastychomper

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For GCMS to work the compounds have to be capable of being carried in the gas phase.  That means if you want to look at polymers, they will need to be broken down into relatively small chemical units so that they can be vaporised by the instrument.  Either that, or try to find a 'fingerprint' of volatile additives (plasticisers etc) for each possible plastic.

For the tissue samples, I agree you'd need to do a lot of separation (such as by GC) before you can get down to identifying your compound(s) of interest.  If you can remove enough interferences then FTIR might do the job.  There is at least one device on the market that claims to detect something like 10,000 different organic compounds using FTIR and Raman scattering.

Conceivably, you could prepare your tissue sample, put the result down a GC column, and then use FTIR for the detection.  When you come to look for plastics, skip the GC and just use the FTIR.  I know GC-IR systems exist, but don't have any experience of them, so I don't know ho sensitive it would be.

Offline pgk

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The quantitative detection of endocrine disrupting chemicals demands highly sensible analytical methods. Thus, I doubt whether quantitative IR and/or Raman Spectroscopy can reach such low detection limits.
The common practice (official methods, included) for such purpose, is wetting the polymer with a non-miscible solvent that can solubilize oligomers, additives and auxiliaries, followed by quantitative detection by GC, HPLC, GC-MS or LC-MS. The specific solvent and the specific operational protocol/instrumentation depend on the specific polymer.   

Offline marquis

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The short answer is no, one instrument won't do it.

If you are looking for the base polymer, then FTIR will probably do.  But many
plastics used a variety of fillers (some that won't show up on FTIR).  To identify
many of those, some xray method is usually used.  Some plasticizers(such as DOP),
if used in high levels, will show up on FTIR.  But not all of them.  And then you have
minor additives, stabilizers, lubiricants, etc.  This usually brings in LC, GC/MS, etc.  And a lot of
additives, such as carbon black will take thermal methods.

If you can limit the type of chemicals you are looking for, you may be able to get away
with FTIR.

I worked with medical polymers for many years.  Even with a wide spread
of instrumets, we still couldn't find all of the material.

Good luck

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