By Chris Allen on Thursday, May 27, 2004 - 04:17 am:

I have developed a combined method for the analysis of the antioxidants BHA and Propyl Gallate in pig feed samples, with 65/35 Meoh/THF as the extraction solvent the Propyl Gallate peak will occaisonaly degrade rapidly. Has anybody got any suggestions for improving the stability of the solution (e.g. a more sacrificial antixidant) or a suitable glassware cleaning procedure.

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By Consumer Products Guy on Thursday, May 27, 2004 - 07:47 am:

Dissolve in DMF, make trimethylsilyl derivatives (to make stable), GC on non-polar capillary column.

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By Anonymous on Thursday, May 27, 2004 - 07:55 am:

Chris,
I wonder if there might be some trace peroxides in your THF. These might degrade the anitoxidants pretty rapidly also. Can you get just as good extraction efficiency w/o the THF? MIght be worth an experiment or 2.

Regards,
Mark

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By Chris Allen on Thursday, May 27, 2004 - 11:51 am:

I am currently using HPLC grade THF which has a maximum peroxide content of 0.05%, but there is the option of using AR grade which is stabilised and has a maximum of 0.001% peroxides. The degradation does not appear across a whole batch of extraction solvent some solutions will degrade within a couple of hours whilst others are stable overnight. Any suggestions on glassware or vial contamination?

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By Anonymous on Friday, May 28, 2004 - 11:43 am:

THF stabilized with BHT as an extraction solvent could improve your stability. BHT is an antioxidant it self and could be consumed preferentially in the solution.