How to derivatize in water ?

Hello everyone,



I need some help for my work...
I have a very polar compound to analyse (spinochrome and echinochrome; pigments from sea urchins).They are only soluble in water, alcohol, DMF and DMSO (they don't in pyridine, acetonitrile, ethyl acetate, acetone, ether, dichloromethane,...) but I would like to analyse them in gas chromatography and for that, I must derivatize them.
I have tried BSTFA-TMCS 1% in DMF and DMSO but it seem these solvent denature my molecules... I can't use water or alcohol because BSTFA react with -OH group...
Do you know how derivatize a polar compound with water as solvent ?

Please help.

I didn't find the right solution from the Internet.

References:
www.chromforum.org/viewtopic.php?t=24430
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Thanks