Dear All,
Solid phase extraction (SPE) commonly forms part of LCMS, GCMS analytical chemistry or in vitro bioassay testing workflows to screen for organic environmental chemicals. Once samples have been passed through columns (E.g. HLB, C18, C8 etc.), the organic compounds are eluted using a solvent, dried and re-constituted in the solvent of choice.
The drying step is typically performed using nitrogen gas. I have seen protocols describing the drying of SPE extracts under a stream of air (such as in an extraction hood) instead of nitrogen.
Is there a particular reason why N2 is used for drying? Such as chemicals becoming oxidized? Could simple drying using air compromise the integrity of a sample?
Have you background sampled the air in your lab and in a test lab where samples are being prepped? There's all kinds of stuff about in the air that GC will detect.
N2 from a good source is pure, and dry. Lab air, could contain ... well, almost anything.
Thanks Rob Darrington for the response.
We are currently using N2 gas for drying and have not tested air quality in the lab. From a practical perspective using air instead of N2 gas will save both money and effort and that is why I posted the question.
Could the use of a compressor with in-line filters be a possible fix for the concern of atmospheric chemicals being introduced in samples?
Most folks that I have seen who use N2, either have a sitewide supply which is delivered by tanker truck, or, in smaller facilities have a N2 generator.
A compressor would need a receiver tank to give capacity, and then the oil / water clean up system to remove compressor oil and moisture from the system. I'm sure some kind of filters could be added to remove any other impurities. As ever, the challenge with any filter is how one knows when the filter is spent, and should be changed.
I am a bit out of date since I last benchmarked costs of the above two solutions, and the price of everything has gone crazy these last few years, but prior to the new normal a N2 generator and a complete compressor system with clean up came out about the same kind of investment. That could have changed.
It's a long time since I visited your faculty, there was a vacuum concentrator within the plant metabolomics group, that may be a potential alternative. I remember that the researcher leading the group had done some clever GM work to double the sucrose output of sugar cane.
[For full disclosure, I work for the company that makes that vacuum equipment.]
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