Pharmaceutical determination in surface and wastewaters using high-performance liquid chromatography-(electrospray)-mass spectrometry

A method was developed to determine 11 pharmaceutical compounds in water samples. The method uses SPE and HPLC coupled to MS (LC/MS) using ESI in both positive and negative modes. Three different sorbents were compared for the extraction of analytes from river and sewage treatment plant (STP) waters and OASIS HLB provided the best results. For the solid-phase extraction of 500 mL of river water samples, the recoveries were between 41 and 101% with the exception of acetaminophen, salicylic acid and naproxen. The LODs were between 3 and 5 ng/L for all the compounds, except naproxen which had an LOD of 15 ng/L. Acetaminophen, caffeine, carbamazepine, bezafibrate and ibuprofen were found in three of the tested river samples at ng/L levels and among them, the highest values were for caffeine and bezafibrate with 305 and 363 ng/L, respectively. For the influent and effluent water samples of the STP, volumes of 100 and 250 mL were used, respectively, to obtain acceptable recoveries. All the compounds showed recoveries between 33 and 91% for effluent samples and 33-72% for influent samples, with the exception of acetaminophen, salicylic acid and bezafibrate, which had lower recoveries. The method developed enabled pharmaceuticals in the influent and effluent sewage waters to be determined in five campaigns carried out between February 2004 and June 2005. Several pharmaceuticals were found in the influent samples: for instance, maximum concentrations of ibuprofen and caffeine were 6 and 40 microg/L, respectively.