Sil-prep shelf life

Chromatography Forum: GC Archives: Sil-prep shelf life
Top of pagePrevious messageNext messageBottom of pageLink to this message  By ves on Tuesday, January 6, 2004 - 02:50 pm:

I have a student that is derivitizing some bile acids and sterols. Sil-prep is used (combination of pyridine, hexamethyldisilazane, and chlorotrimethylsilane). How often should this mix be made when using on a continuous basis - every day, two days, etc?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, January 7, 2004 - 05:06 am:

Ves,

This Sil-prep, aka "Sweeley reagent", can be stored for 3-6 months and still be usable. However, it must be kept in a dry environment. Usually a bulk is prepared and is portioned out as needed. Be sure to use redistilled pyridine to minimize artifactual peaks near the solvent peak. This is not a big problem for steroid derivitization. If a lot of ammonium chloride (from atmospheric water entering the container) is formed during storage consuming the reagent, one may question the sealing of the container and the suitability of the reagent for its application.

You are welcome to email me or phone me if you wish to discuss this reagent.

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rgeorge@sial.com


Top of pagePrevious messageNext messageBottom of pageLink to this message  By ves on Wednesday, January 7, 2004 - 06:52 am:

Rodney, thanks. The solution clouded up after a couple of days. The student then used it in a derivitization procedure for some bile acids. Two of the procedures did not work, but the third one (late last night) had one, good strong peak. I kinda wish the third prep had failed. Cloudy is not good, I hope.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, January 7, 2004 - 08:12 am:

That is correct. The cloudiness is the ammonium chloride.

Rodney George


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