Concurrent purification of sterols,triterpenols and alkenones from sediments for hydrogen isotope analysis using high performance liquid chromatography

Three methods are presented on how to purify acetylated sterols, acetylated triterpenols and individual alkenones for hydrogen isotope analysis from marine and lacustrine sediments using reverse-phase high performance liquid chromatography (RP-HPLC). The main advantages over previous HPLC methods are reduced operator time, increased automation and the ability to simultaneously purify multiple target compounds from a sample. These gains are achieved primarily by acetylating compounds prior to purification rather than after, and also by using a fraction collector with semi-preparatory rather than analytic configuration. The effectiveness of the method is demonstrated for (i) dinosterol and taraxerol in sediment from the brackish pond Poza del Diablo, Galápagos, (ii) for di- and tri-unsaturated C₃₇ and C₃₈ alkenones in cultured Emiliania huxleyi, (iii) for brassicasterol, and di-, tri- and tetra-unsaturated C₃₇ alkenones in sediment from Manito Lake, Saskatchewan, Canada, and (iv) for brassicasterol, dinosterol and di-, tri- and tetra-unsaturated C₃₇ alkenones in sediment from the Great Salt Lake, Utah. The purification process yields 80–90% recoveries and results in no measurable hydrogen isotope alteration.