While preparing sililating darivative, adding 1 ml to 10 mg FA and injecting onto DB23, BP1 & DB1 capillary columns of J & W gives lots of tailing & the peaks are not sharp and comparable to methyl esters of fatty acids prepared by using methanol & thionyl chloride. please advise


I would also like to know what is the accuracy of internal standard method

I'd abandon the silation and use methyl esters.

You can do free fatty acids on FFAP phases and get excellent peak shapes. We use a ZB-FFAP routinely. It is less sensitive than FAMEs and so on - but if you don't need the sensitivity why not go for the least complicated option?
John

I work for soap company - we usually make fatty acid methyl esters (boron trifluoride-methanol or sulfuric acid -methanol), but have also used TMS derivatization. What exactly are you trying to do?

From your description it sounds like you are not silylating your fatty acids.

We use BSTFA to derivatize for trimethylsilyl derivatives.