title: Determination of sulfadiazine in phosphate- and DOC-rich agricultural drainage water using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry.
abstract: Trace levels of the veterinary antibiotic compound sulfadiazine (SDZ) can be determined in agricultural drainage water samples with this new method. Optimized sample pretreatment and solid-phase extraction was combined with liquid chromatography coupled to tandem mass spectrometry (SPE LC-MS/MS) using positive electrospray ionization. The linear dynamic range for the LC-MS/MS was assessed from 5 μg/L to 25 mg/L with a 15-point calibration curve displaying a coefficient of correlation r(2) = 0.9915. Agricultural drainage water spiked at a concentration of 25 ng/L gave recoveries between 63 and 98 % (relative standard deviation 15 %), while at 10 ng/L, it showed a lower recovery of 32 % (relative standard deviation 47 %). The final SPE LC-MS/MS method had a limit of detection (LOD)(Method) and a limit of quantification (LOQ)(Method) of 7.5 and 23 ng/L agricultural drainage water, respectively. Determination of SDZ, spiked at a realistic concentration of 50 μg/L, in artificial drainage water (ADW) containing common and high levels of phosphate (0.05, 0.5, and 5 mg/L) gave recoveries between 70 and 92 % (relative standard deviation 7.4-12.9 %). Analysis of the same realistic concentration of SDZ in ADW, spiked with common and high levels of dissolved organic carbon (2, 6, and 15 mg/L) confirmed the possible adaptation of a tandem solid-phase extraction (strong anion exchange (SAX)-hydrophilic-lipophilic balance (HLB)) followed by liquid chromatography-tandem mass spectrometry methodology. Recoveries obtained ranged from 104 to 109 % (relative standard deviation 2.8-5.2 %). The new methods enable determination of the veterinary antibiotic compound SDZ in agricultural drainage water from field experiments and monitoring schemes for phosphate- and dissolved organic carbon (DOC)-rich water samples in intensive farming areas.
authors.affiliation: Section of Environmental Chemistry and Physics, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark, leon@plen.ku.dk.
authors.forename: P A Léon
authors.initials: PA
authors.lastname: Bouyou
authors.forename: Johan J
authors.initials: JJ
authors.lastname: Weisser
authors.forename: Bjarne W
authors.initials: BW
authors.lastname: Strobel
mesh_terms: D000383:Agriculture; D000890:Anti-Infective Agents / Q000032:analysis; D002244:Carbon / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D004322:Drainage; D057230:Limit of Detection; D010710:Phosphates / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D013411:Sulfadiazine / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000890:Anti-Infective Agents; D010710:Phosphates; D014874:Water Pollutants, Chemical; D013411:Sulfadiazine; D002244:Carbon