DETERMINATION OF THE U-37(K) INDEX IN GEOLOGICAL SAMPLES

The U-37(K) index is a tool for sea surface paleotemperature (SST) reconstruction and is defined by the relative abundance of three long-chain alkenones (C-37) commonly found in Quaternary marine sediments. A simple, fast, and reliable analytical technique is required for the analysis of these compounds in deep-sea sediment cores in order to provide time series of SST and hence contribute to the understanding of past climates. The method described here employs a robotic workstation for sample preparation and gas chromatography (GC) coupled to mass spectrometry with ammonia chemical ionization (CI-MS) to quantify the targeted analytes. This semiautomated procedure provides enhanced sensitivity, selectivity, and speed of analysis when compared to conventional, manual sample preparation and GC name ionization detector analysis.