Hydrazine reduction in the gas liquid chromatographic analysis of the methyl esters of cyclopropenoic fatty acids

A Capillary GC Determination of Cyclopropenoid Fatty Acids in Cottonseed Oils

“…However, within reasonable running time, no extraneous peaks were observed other than for 17:0 and 18CE (chromatograms not shown). Although such peaks were not observed, if any thermal alterations occurred as previously reported with the traditional polar columns (Recourt et al, 1967;Bianchini et al, 1981;Conway et al, 1985), the result would have been reduced area percentage of 18CE relative to 17:0 with rising temperatures. However, results showed very consistent values for the area percent of 18CE ranging from 54.4% at 150°C to 52.4% at 220°C without regard to the running temperatures.…”

“…When the temperature was raised to 22o"C, the thermal instability of 19CE was clearly demonstrated by an area decrease of as much as 10% as compared with the value for 150°C. When 19CE was individually run at 17O"C, the area of the single major peak accounted for no less than 98% without any significant extraneous peaks, unlike the observation of five peaks with 8% decomposition at the same temperature (Conway et al, 1985). All these results imply that thermal alterations of CPEFA methyl esters are negligible or insignificant during their GC analysis on the Supelcowax 10 column.…”

“…1. Two peaks labelled as 18CE and 19CE were assigned as such by comparing their equivalent chain length (ECL) values of 17.93 and 18.90, respectively with literature values (Bianchini et al, 1981;Conway et al, 1985);…”

“…Initially, 18CE preparations were mixed with about equal amounts of methyl heptadecanoate (17:0) and the mixtures run on the polar Supelcowax 10 column at various temperatures ranging from 150°C to 220°C. This simplified model mixture was intended to reveal any indication of thermal alterations manifested as peaks due to either decomposed or polymerized materials on the gas chromatograms, because it was claimed that decomposed peaks might be hindered under peaks of other FAMES (Conway et al, 1985). However, within reasonable running time, no extraneous peaks were observed other than for 17:0 and 18CE (chromatograms not shown).…”

“…However, GC of CPEFA methyl esters has not been successful; unlike other fatty acid methyl esters (FAMES), CPEFA methyl esters were reported to be thermally decomposed on the conventional polar columns (Recourt et al, 1967). In order to make CPEFAs heat stable for GC analysis, a second derivatization altering the cyclopropene moiety was sought through either hydrogenation (Cornelius et al, 1965;Bland et al, 1984;Conway et al, 1985) or reaction with methyl mercaptan (Raju and Reiser, 1966) or methanolic silver nitrate (Kircher, 1965; Authors Park and Rhee are with the Food Protein R & D Center, Faculty Mail Box 183, Texas A&M Univ., College Station, TX 77843-2476. Schneider et al, 1968).…”