Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO 3 impregnated rods

The relative FID responses for Iatroscan analyses of cis and trans isomers of methyl esters of 18∶1†6, 18∶1†9 and 18∶1†11 on Chromarods‐S impregnated with AgNO 3 were studied at load levels ranging from 0.5 to 20 μg, using methyl stearate as internal standard. The FID response correction factors were greater for the cis than for the trans isomers. The correction factors were relatively constant in the 10–20 μg interval, but increased in the range 0.5–5 μg. Separation of tristearin, triolein, trilinolein and trilinolenin also was obtained on Chromarods‐S impregnated with AgNO 3 using a mixture of benzene: chloroform: acetic acid (90∶8∶2) as the solvent system. The relative FID responses for the triolein, trilinolein and trilinolenin were determined at load levels ranging from 0.5 to 14.3 μg using tristearin as an internal standard. The FID response correction factors of these three triglycerides differed significantly for load levels of 1.0, 2.5 and 5.0 μg. However, the factors could be considered as being equal in the range 10 to 14.3 μg. Correction factors were not affected by repeated re‐use of the same set of Chromarods. Several hundred separations and scans appeared feasible.