QUANTITATIVE-DETERMINATION OF MONOGLYCERIDES AND DIGLYCERIDES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND EVAPORATIVE LIGHT-SCATTERING DETECTION

Neutral lipid classes were separated with normal-phase high-performance liquid chromatography, and mono- and diglycerides were determined with an evaporative light-scattering detector (ELSD). The 1,3-diacylglycerols were resolved from the 1,2-diacylglycerol positional isomers, although some 1,3-diacylglycerols of low molecular weight interfered with the 1,2-diacylglycerols of high molecular weight. For monoglycerides, the separations between 1-(and 3-)acyl and 2-acylglycerols were optimized only between those pairs with identical fatty acyl groups. Samples were dissolved in a solvent mixture and analyzed without derivatization. The results (monoglyceride) obtained from this method agreed well with those derived from gas chromatographic and supercritical fluid chromatographic methods. The universal nature of the ELSD makes this method applicable to oils and emulsifiers containing both saturated and unsaturated fatty acyl moieties.