Alpha hydroxy acids

Chromatography Forum: GC Archives: Alpha hydroxy acids
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, January 6, 2000 - 10:13 am:

Anybody have experience in assaying for alpha hydroxy acids in cosmetics products? Is there a standardized FDA/USP test method? I have GC and GCMS available, as well as HPLC with varied detectors (I'm also posting on the HPLC board).


Top of pagePrevious messageNext messageBottom of pageLink to this message  By juddc on Friday, January 7, 2000 - 01:34 pm:

Depending upon your concentration, the AHA's you're looking for, and your matrix, reversed phase HPLC may be useful. Inertsil C8 works well for me with a 99:1 0.1% H3PO4:MeOH MP (pH = 2.5).
You may be able to go to 100% aqueous if you need to, but stationary phase collapse could become a problem (though is a bit less prevalent with a C8 than it is with C18). There are columns available that are more resistant to collapse, though their brandnames escape me at the moment.

If your concentrations are low and/or you have problems with matrix components (excipients), you can derivatize your AHA's and detect lower levels at ca 254 nm. Check out Regis Inc. They have an excellent catalog of derivatization reagents along with procedures for their use.

Drop a line at juddman@peconic.net if you wish to discuss further.

Chris


Top of pagePrevious messageNext messageBottom of pageLink to this message  By jwarwick on Monday, January 31, 2000 - 12:53 pm:

This would be my area of expertise. For GC or GC/MS I would suggest that you silate the sample with availible silation kits from Regis. Use a DB-5 column for analysis and heat the sample to drive the reaction to the di-silated form.

A useful article on CE/HPLC appears in "Analyst, July 1997, vol. 122,pages 709-713" on dermatological formulations using lactic acid analysis.


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