Determination of fecal sterols in the sediments of different wastewater outputs by GC-MS

An improved method for the analysis of fecal sterols in sediments was applied to distinguish livestock wastewater, domestic sewage, and industrial wastewater pollution in the receiving waters of Taiwan's rivers. The method included direct saponification, solvent phase extraction, derivatization with N-methyl-N-trimethyltrifluoroacetamide and catalyst, and separation by gas chromatography with an HP-50+ capillary column, followed by qualitative and quantitative analysis by mass spectrometry. Recoveries of nine sterols by this method were 78-89%. The indicators of biopollution markers ((coprostanone x coprostanol)/epicoprostanol) in different sources of wastewater effluents were calculated as human 0.913 ± 0.251, pig 0.224 ± 0.135, cow 0.023 ± 0.001, duck 0.007 ± 0.001; such indicators are feasible for distinguishing between different animal sources of fecal pollution in water.