Application of LC-QTRAP-MS and LC-TOF/MS to the Determination of Pharmaceuticals and Metabolites in Wastewater

摘要

This article describes the development of an enhanced liquid chromatography-mass spectromerry (LC-MS) method for the analysis of a selected group of 57 organic contaminants in wastewater. This group comprises 39 Pharmaceuticals belonging to different therapeutical classes and 10 of their most frequent metabolites. Six pesticides and two disinfectants were also included. The LC-MS method was developed using a hybrid quadrupole/linear ion trap (Q TRAP) analyzer operating in selected reaction monitoring (SRM) mode (in both positive and negative electrospray ionization) in combination with a time-of flight (TOF) mass analyser. The application of both techniques provided very good results in terms of accurate quantification and unequivocal identification. Quantification was based on the use of a linearly accelerating (LINAC) high-pressure collision cell, which enable the analysis of a high number of compounds with enough acquisition data points for an optimal peak definition in SRM. Unequivocal identification was provided by the acquisition of at least two SRM transitions and by obtaining accurate mass measurements of the identified compounds with errors lower than 2 ppm. As an alternative for compounds where a second transition cannot be detected by Q-Trap-MS, the application of survey scans in enhanced product ion (EPI) was evaluated.rnThe analytical performance of the method was evaluated in effluent wastewater samples. Linearity of response over three orders of magnitude was demonstrated (R~2>0.99 for most compounds). Matrix effects resulting in suppression of the response were frequently observed, between 2-50% for most of compounds, except 4-DAA and 4-AA, which exhibit higher values (68%). Signal enhancement was also detected in 16 compounds. Method limits of detection (LOD) were between 0.1-50 ng L~(-1). Finally, the methodology was successfully applied to a monitoring study intended to characterize wastewater effluents of five sewage treatment plants (STPs) in Spain. The selected STPs represent different locations and activities (urban, industrial or agricultural). Preliminary results are presented showing the presence of most of compounds with mean concentrations ranging from 4 ng L~(-1) in the case of atrazine to 7086 ng L~(-1) for paraxanthine.