Sterols of the cockle Cerastoderma edule. Evaluation of thermostable liquid phases for the gas-liquid chromatographic-mass spectrometric analysis of the trimethylsilyl ethers of marine sterols.

Some recent liquid phases for gas-liquid chromatography with improved thermostability have been evaluated for their use in the gas-liquid chromatographic-mass spectrometric (GC-MS) analysis of the complex mixtures of sterol trimethylsilyl ethers obtained, often in small amounts, from marine organisms. A combination of Dexsil 300 GC, SE-30 "ultraphase" and Silar 5CP is recommended for use in this technique because of the excellent separating efficiency and the very low substrate bleed. GC-MS analysis of the sterol trimethylsilyl ethers obtained from the cockle Cerastoderma edule has established the identity and relative proportions of the eleven sterols present.