Simultaneous Determination of Trimethoprim, Sulfadiazine, Florfenicol and Oxolinic Acid in Surface Water by Liquid Chromatography Tandem Mass Spectrometry

A liquid chromatographic/tandem mass spectrometric method using atmospheric pressure chemical ionisation (LC-APCI-MS-MS) was developed for simultaneous determination of trimethoprim, sulfadiazine, florfenicol and oxolinic acid in surface water. The compounds were extracted by solid phase extraction on a polymeric sorbent. Two transition products were monitored for each compound. The detection capabilities related to the transition products of lowest abundance were 1 ng L^–1 for trimethoprim, sulfadiazine and florfenicol and 2 ng L^–1 for oxolinic acid. The mean recoveries were 84%, 83%, 96% and 78% at a level of 10 ng L^–1. The relative repeatability standard deviations were less than 11% at a level of 10 ng L^–1.