Glass capillary gas chromatography‐mass spectrometry of wax esters, steryl esters and triacylglycerols

Complex mixtures of wax esters, steryl esters and triacylglycerols isolated from representative biological and geochemical samples have been analyzed using combined high resolution gas chromatography and electron impact and chemical ionization quadrupole mass spectrometry. These low volatility neutral lipids containing up to 65 carbons were chromatographed intact on 15–20 m high‐temperature (upper limit: 370 C) persilylated SE‐52 and SE‐30 glass capillary columns. Discrimination effects due to adsorptive losses and degradation were minimized using a nonvaporizing on‐column injector and a direct all‐glass capillary connection (370 C) to the quadrupole mass spectrometer. Structural information regarding the fatty acid and alcohol moieties was found to be maximal for methane‐CI spectra in the case of wax and steryl esters, whereas EI spectra were most useful in interpreting triacylglycerol structures. Principal features of the EI and CI fragmentation patterns are discussed. The molecular composition of complex mixtures of these lipids is reconstructed for selected samples.