A specific and sensitive analytical method was developed to extract and quantify spectinomycin and lincomycin in liquid hog manure supernatant and simulated rainfall run-off from manure-treated cropland. Sample extracts were prepared using solid-phase extraction (SPE) employing a weak cation-exchange resin (Oasis WCX) for extraction of spectinomycin. An Oasis HLB cartridge was used for extraction of lincomycin. Hydrophilic interaction chromatography (HILIC) was used to obtain the necessary separation of the two antibiotics from interfering compounds and to provide baseline separation. Analytes were detected using atmospheric pressure chemical ionization tandem mass spectrometry. Extraction recoveries were 77% for lincomycin and 84% for spectinomycin in liquid hog manure supernatant, and 89% for lincomycin and 95% for spectinomycin in run-off water. The corresponding limits of quantitation were 6.0 and 0.040 microg l(-1) for spectinomycin and lincomycin, respectively, in liquid hog manure supernatant and 0.2 and 0.008 microg l(-1) for spectinomycin and lincomycin, respectively, in run-off from manure treated cropland. The method is suitable for monitoring the environmental fate and transport of these two antibiotics in both liquid hog manure and agricultural field run-off.