By Joe on Friday, November 7, 2003 - 07:38 am:
We're attempting to develop a method for the determination of trace levels (<20 ppm) of silicone oils in various matrices. We've been experimenting with AA and FTIR methods, but have also been asked to pursue chromatographic techniques. My concern is that I need a low-res approach to prevent resolving the peaks in the MW distribution. LC-wise, we have several ELSDs, which we intend to use as our detector, but we're looking for appropriate chromatographic parameters. GC-wise, we also have various techniques available, so, we're open to trying anything. I would appreciate any ideas. Thank you in advance.
Joe
By Uwe Neue on Friday, November 7, 2003 - 09:32 am:
I do not see your concern about resolving peaks. For quantitation, you can alwasy add up the different areas.
By Joe on Friday, November 7, 2003 - 12:07 pm:
Uwe,
My main concern is sensitivity...if I can get a method that resolves the distribution AND is sensitive enough in the 1-20 ppm range, I'll certainly take it. I just thought that my best shot at a sensitive method will be one which doesn't resolve the entire distribution. Any ideas?
Joe
By Anonymous on Thursday, November 13, 2003 - 02:01 am:
Joe,
As you mentioned you are expecting MW distribution.How should GC work for higher molecular compounds? How should HPLC be an approach?
I never checked your problem in praxis so I can't really give you an advice.The only method that remains to be tested is SEC with a column of low exclusion limit to avoid distribution. With RI detection you should take toluene as eluent, alternatively ELSD/THF.But.. my concern is also.. sensitivity.
If matrix allows I would prefer the 'inorganic approach'.
PETER
By Joe on Thursday, November 13, 2003 - 09:04 am:
Peter,
Thanks for the input. Your questions are exactly what I've been dealing with here. I have a preliminary quantitative FT-IR method and am looking into an ICP method (my matrix is an organic extract and I'm looking into the accessory for this on ICP). You're right...I think they are the most promising. I was asked to investigate chromatographic techniques as an alternate route. I tried the SEC/ELSD approach, but even with total exclusion, the peak still broadened too much to give me the sensitivity that I need. I appreciate the input, and if there are any other ideas out there, I'm open to suggestions. Thanks
Joe