Figure 3: Gas chromatography of linoleic acid methyl ester isomer mixture standards. 1, C18:2, 9t12t; 2, cis-9,trans-12-octadecadienoic acid methyl ester (C18:2, 9c12t); 3, trans-9,cis-12-octadecadienoic acid methyl ester (C18:2, 9t12c); 4, C18:2, 9c12c.