Validation and field testing of LC-MS/MS analysis of animal waste markers

Contamination of water by animal wastes degrades water quality and may cause disease in humans and animals.1 Determining the individual sources of the contamination is important both to allow effective remediation of polluted waters and to identify waters where human disease vectors may be present.1 Bile acids and fecal sterols are molecular markers which can identify which animal species may have contributed to contamination of a particular water.2 The profiles of relative concentrations of bile acids and fecal sterols are characteristic of the waste of individual animal species.2 LC-MS/MS affords a potentially much superior means of analyzing these compounds in comparison with the traditional GC-MS methods. We have developed and validated an LC-MS/MS method for analysis of animal bile acids and fecal sterols. The method employs a standard C-18 column and a gradient of methanol:acetonitrile and 0.2 mM ammonium acetate in water. We have also developed a preconcentration method for the markers using C-18 extractions discs. The method has been tested by analysis of local sewage treatment plant effluent and a farm stream polluted by cattle waste.