Separation of 20∶4n−6 and 20∶4n−7 by capillary gas‐liquid chromatography

Abstract

The use of a capillary column coated with 100% cyanopropyl polysiloxane (CP(TM)Sil 88) allows the separation of several fatty acids associated with fat deficiency. Starting with liver mitochondrial phospholipids of weanling rats fed a fat-free diet, an unusual fatty acid was isolated, along with 20:4n-6, by thin-layer chromatography on AgNO3-impregnated silica gel plates. After partial hydrazine reduction of these acids, the resulting monoenes were isolated and subjected to ozonolysis in BF3/methanol. The resulting monomethyl and dimethyl esters were identified by gas chromatography/mass spectrometry. Our data indicate that the unusual component corresponds to 20:4n-7. Based on published biochemical and analytical studies and on our own chromatographic retention data, some of the other unusual fatty acids were tentatively identified as 18:2n-7, 20:2n-7 and 20:3n-7. The CP(TM)Sil 88 column appears to be a simple and useful tool for the separation of fatty acids of the palmitoleate series.

Geometrical isomers of linolenic acid in low‐calorie spreads marketed in France

“…Cis and trans monoenes (localized and extracted as described above) were then submitted to ozonolysis in BFJmethanol (7). The resulting dimethyl esters (DME) were further identified by GLC/mass spectrometry (GC/MS) under conditions recently described (22).…”