Development and application of an automatic on-line SPE-LC-MS/MS method for the analysis of wide-range polarity pharmaceutical compounds in aqueous matrices

Modern environmental analytical chemistry must deal with the increasing demand of high-throughput analysis. Moreover, the environmental monitoring of organic micropollutants in water samples is a fairly laborious issue, due to a number of reasons, such as the need of the simultaneous determination of many compounds, frequently characterized by a wide range of physicochemical properties and capable to exert negative effects on the environment, even at very low concentrations (i.e. ppb-ppt levels). All these issues can be faced using on-line solid phase extraction coupled to tandem mass spectrometry (on-line SPE-LC-MS/MS), which has been successfully used for the monitoring of some classes of organic micropollutants in various aqueous matrices. Pharmaceutical compounds (PCs) in aqueous matrices are matter of environmental concern owing to their widespread use, continuous release, persistence, and increasing evidence for their ecotoxicological effects. Pharmaceuticals are excreted either as such or as metabolites after human administration and via the sewage system they reach wastewater treatment plants (WWTPs) where they are often inefficiently removed. In this work, on-line SPE-LC-MS/MS was applied to the development of a highthroughput analytical method for the determination of a number of PCs characterized by a wide range of polarity. Antibiotics, beta-blockers and anti-inflammatory drugs most used in Italy were selected according to the reports of the Italian Medicine Agency, together with some metabolites. Different SPE sorbents, such as the poly(divinylbenzene-co-N-vinylpyrrolidone) (PVB-VP) and PVB-VP functionalized with a weak cation exchange group, and different analytical columns were tested. Under the best experimental conditions, recoveries included in between 40 and 120% were obtained on MilliQ water. Apparent recoveries significantly differed from these values, mainly due to matrix effects. Detection limits were however included from subng/ L to tens of ng/L, with a total analysis time of about 25 minutes per sample. The analysis of various effluent WWTP samples evidenced the presence of several PCs, especially antibiotics and beta-blockers, at concentrations as high as tens of μg per litre.