Organic compound, analytes and surrogates are extracted from 1 L of water sample by liquid-liquid extraction (LLE) with methylene chloride or by passing 1 L of sample water through a cartridge or disk containing a solid inorganic matrix coated with a chemically bonded C18 organic phase or a neutral polystyrene/divinylbenzene polymer (liquid-solid extraction, LSE). If LLE is used, the analytes are concentrated in methanol by evaporation of the methylene chloride and addition of methanol (solvent exchange). If LSE is used, the analytes are eluted from the LSE cartridge or disk with a small quantity of methanol and concentrated further by evaporation of some of the solvent. The sample components are separated, identified, and measured by injecting an aliquot of the concentrated methanol solution into a high performance liquid chromatograph (HPLC) containing a reverse phase HPLC column and interfaced to a mass spectrometer (MS) with a particle beam (PB) interface. Compounds eluting from the HPLC column are identified by comparing their measured mass spectra and retention times to reference spectra and retention times in a data base. Reference spectra and retention times for analytes are obtained by measurement of calibration standards under the same conditions used for samples. The concentration of each identified component is measured by relating the MS response of the quantitation ion produced by that compound to the MS response of the quantitation ion produced by the same compound in a calibration standard (external standard). Surrogate analytes, whose concentrations are known in every sample, are measured with the same external standard calibration procedure. An optional isotope dilution procedure is included for samples which contain interfering matrix or coeluting compounds.