Samples are dechlorinated with sodium thiosulfate and protected from microbial degradation using 2-mercaptopyridine-1-oxide sodium salt during sample collection. Samples are fortified with surrogates and passed through solid phase extraction (SPE) disks containing octadecyl (C18) functional groups in order to extract the method analytes and surrogates. The compounds are eluted from the solid phase with a small amount of methanol. The extract is concentrated to dryness with nitrogen in a heated water bath, and then adjusted to a 1-mL volume with 50:50 methanol: water after adding the internal standards. An aliquot of the sample is injected into an LC equipped with a C18 column that is interfaced to a MS/MS. The analytes are separated and identified by comparing the acquired mass spectra and retention times to reference spectra and retention times for calibration standards acquired under identical LC-MS/MS conditions. The concentration of each analyte is determined using the internal standard technique.