Rapid determination of trans-fatty acids in human adipose tissue. Comparison of attenuated total reflection infrared spectroscopy and gas chromatography.

A rapid attenuated total reflection (ATR) infrared (IR) spectroscopy procedure was used for quantitating the levels of total trans-fatty acid methyl ester (FAME) derivatives in neat (without solvent) test samples isolated from human adipose tissue. This procedure requires no weighing of the laboratory sample. The single-beam spectrum of the trans-containing FAMEs was 'ratioed' against that of a reference material having only cis double bonds in order to obtain a symmetric absorption band at 966 cm(-1) on a horizontal background. A single-reflection ATR diamond cell that requires only about 1 microl of neat FAMEs was used. The average level of trans-fatty acids in human adipose tissue found by ATR (3.07+/-0.27%) was generally higher than that obtained by gas chromatography (2.59+/-0.20%). Reasons for such a difference are discussed.