Tuesday, November 14, 2006
216-5

Analysis of Antibiotics in Surface Water and Soils by Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

Wenlu Song1, Ming Huang2, Wilson K. Rumbeiha2, and Hui Li1. (1) MSU, Dept of Crop & Soil Sciences, 566 Plant & Soil Sciences, East Lansing, MI 48824, (2) MSU, bDiagnostic Center for Population and Animal Health, 4125 Beaumont Rd, Lansing, MI 48910

Analytical methods for simultaneous determination of amprolium, carbadox, monensin and tylosin in surface water and soils were developed using LC-MS/MS coupled with solid-phase extraction (SPE). These four antibiotics are commonly used in animal feeding operations. Surface water sample was mixed with ~10% of methanol in volume, then passed through a Waters Oasis HLB cartridge. The cartridge was preconditioned with methanol and water. After loading the water sample, the cartridge was cleaned up using water, then eluted with methanol containing 2% formic acid. The eluate was analyzed using LC-MS/MS operated in electrospray positive ionization mode. The recoveries were 94% for amprolium, 95% for carbadox, 86% for monensin, and 94% for tylosin. For soil samples, methanol/2% ammonium acetate mixture was used to extract the four antibiotics from soil. The extract was cleaned up using the SPE procedure and analyzed by LC-MS/MS. The recoveries were 81 % for monensin, 91% for tylosin, 56 % for carbadox, and 44% for amprolium.