Xiu-Sheng Miao

DISTRIBUTION OF ACIDIC AND NEUTRAL DRUGS IN SURFACE WATERS NEAR SEWAGE TREATMENT PLANTS IN THE LOWER GREAT LAKES, CANADA

Prescription and nonprescription drugs have been detected in rivers and streams in Europe and the United States. Sewage treatment plants (STPs) are an important source of these contaminants, but few data exist on the spatial distribution of drugs in surface waters near STPs. Samples of surface water were collected in the summer and fall of 2000 at open-water sites in the lower Great Lakes (Lake Ontario and Lake Erie), at sites near the two STPs for the city of Windsor (ON, Canada), and at sites in Hamilton Harbour (ON, Canada), an embayment of western Lake Ontario that receives discharges from several STPs. In a follow-up study in the summer of 2002, samples of surface water and final effluent from adjacent STPs were collected from sites in Hamilton Harbour and Windsor. In addition, surface water and STP effluent samples were collected in Peterborough (ON, Canada). All samples of surface water and STP effluents were analyzed for selected acidic and neutral drugs. In the survey of Hamilton Harbour and Windsor conducted in 2000, acidic drugs and the antiepileptic drug carbamazepine were detected at ng/L concentrations at sites that were up to 500 m away from the STP, but the hydrological conditions of the receiving waters strongly influenced the spatial distribution of these compounds. Drugs were not detected at open-water locations in western Lake Erie or in the Niagara River near the municipality of Niagara-on-the-Lake (ON, Canada). However, clofibric acid, ketoprofen, fenoprofen, and carbamazepine were detected in samples collected in the summer of 2000 at sites in Lake Ontario and at a site in the Niagara River (Fort Erie, ON, Canada) that were relatively remote from STP discharges. Follow-up studies in the summer of 2002 indicated that concentrations of acidic and neutral drugs in surface waters near the point of sewage discharge into the Little River (ON, Canada) STP were approximately equal to the concentrations in the final effluent from the STP. Caffeine and cotinine, a metabolite of nicotine, were generally present in STP effluents and surface waters contaminated by drugs. The antidepressant fluoxetine and the antibiotic trimethoprom were also detected in most STP effluents and some surface water samples. For the first time, the lipid regulating drug atorvastatin was detected in samples of STP effluent and surface water.

Determination of cholesterol-lowering statin drugs in aqueous samples using liquid chromatography-electrospray ionization tandem mass spectrometry

Cholesterol-lowering statin drugs are among the most frequently prescribed agents for reducing morbidity and mortality related to coronary heart disease. Four major statin drugs, atorvastatin, lovastatin, pravastatin and simvastatin, were determined using liquid chromatography-electrospray ionization tandem mass spectrometry with methylammonium acetate as an additive in the mobile phase. Protonated atorvastatin, and methylammonium-adducted lovastatin, pravastatin and simvastatin were selected as precursor ions, and product ions were detected by selected reaction monitoring in positive-ion mode. The instrumental detection limits of atorvastatin, lovastatin, pravastatin and simvastatin are 0.7, 0.7, 8.2 and 0.9 pg, respectively. A solid-phase extraction method was developed to enrich the analytes from aqueous samples. All of the statins were detected in an untreated sewage sample at 4-117 ng/l and in a treated sewage sample at 1-59 ng/1; but only atorvastatin was detected in a surface water sample at 1 ng/l.