The analysis of trans fatty acids in edible oils was very important for their content control. Conditions of gas chromatography and sample preparation were optimized for analysis of trans fatty acids by gas chromatography. After treated by proper extractant and two-step methyl esterifying under the conditions determined by orthogonal design, trans fatty acids in edible oils were transformed successfully into corresponding trans fatty acid methyl esters. The conditions of two-step methyl esterification were ...