Response enhancement for the evaporative light scattering detection for the analysis of lipid classes and molecular species

The response of an evaporative light scattering detector for the analysis of lipids is enhanced by the addition of triethylamine and an equimolar amount of formic acid to the mobile phase. The generality of this phenomenon was demonstrated for different chromatographic techniques and various classes of lipids: for non-aqueous liquid chromatography with a porous graphitic carbon packing for wax esters, fatty acid methyl esters and ceramides; for normal phase liquid chromatography with a PVA-Sil((R)) stationary phase for cerebrosides, digalactosyl-diacylglycerols and phospholipids; and for subcritical chromatography with an octadecyl grafted silica column for ceramides. The response enhancement was quantified with cholesterol in non-aqueous liquid chromatography with a porous graphitic carbon packing. This response modifier enhances the detection response of lipids and does not significantly alter retention excepts in case of zwitterionic phospholipids.