Swede
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Commercial chemical analysis services
Has anyone made use of commercial services to test the purity and/or contaminants of a chemical produced in a home lab? Obviously, depending upon the
material in question, there are probably a dozen methods to get a rough idea of the chemical(s) in the sample in question, but it is tough to beat
modern technology like NMR, GC, etc, especially to determine the exact proportions.
My specific need is to verify the methodology I use to clean perchlorates of chlorate remnants via reduction with metabisulfite or similar. I would
love to get an accurate report that would say something like:
99.72% KClO4
00.16% KClO3
00.08% KCl
00.04% K2SO4
or whatever. Obviously it would be a "pay to play" deal, and I don't mind paying a reasonable amount. Anybody done something similar, and if so, any
recommendations for commercial services?
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Rosco Bodine
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There are probably specific colormetric spot tests that could give you that level of accuracy for determinations for those constituents, without
having to resort to outsourcing the work to a laboratory. Anticipating your question as to what colormetrics would be used, I haven't checked to see,
but I can just about guarantee it that there are such tests which have been devised for the same quality control and analysis reasons as are your
interest. Clean recrystallizations alone will typically give purity at or better than 99.9% purity.
[Edited on 17-12-2009 by Rosco Bodine]
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entropy51
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Some very useful tests for practical levels of purity, including quantitative assays, can be found in the book Chemical Reagents - Their Purity and Tests, which is in the forum library. A college text on quantitative analysis would also point to many
assays for purity. I think most of us here would be happy to know that something we made was 99% pure, never mind what the remaining 1% was.
I think you may find that commercial analytical services are not exactly cheap. If you have an assay that you can run for yourself, you can run lots
of them to optimize synthetic and purification procedures. When distilling acids, for example, I sometimes titrate the product many times as the
distillation proceeds so that I have some idea how the process is progressing. I find that very useful in terms of collecting fractions.
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Swede
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I know I should probably not be lazy and just dig in and do it, but I was hoping a commercial lab could get an accuracy I could not hope to achieve.
If they want $350 to analyze a gram, forget it. If it was $75, I might be tempted.
entropy, I will look into the book. It sounds like something that I could definitely use. Thanks.
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Swede
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Interestingly, I did have one reply via email, and they wanted $315 to analyze a perchlorate sample for the presence of chlorates, and ANOTHER $315 to
look for sulfates. Uhh, no thanks.
Maybe we are all in the wrong business. In my research for these companies, the majority deal with litigation, and command big bucks for serious
analysis of all sorts of chemicals and materials.
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JohnWW
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Analysis for sulfate (provided it is in the absence of carbonate, and other anions forming insoluble salts) should be quite straight-forward and
inexpensive, requiring only a barium salt, Buchner filter with filter paper, vacuum filtration flask, a drying oven (pie warmer), and an analytical
balance.
[Edited on 21-12-09 by JohnWW]
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