A single run, rapid polarity switching method for determination of 30 pharmaceuticals and personal care products in waste water using Q-Exactive Orbitrap high resolution accurate mass spectrometry

Abstract

The analytical capability of the UPLC-Q Exactive™ Orbitrap MS was exploited for simultaneous determination of 30 acidic and basic PPCPs in a single run, using rapid polarity switching of the electrospray ionisation source. Full scan MS mode at resolution of 35,000 FWHM, Automatic gain control (AGC) target of 1E6 ions at injection time of 50 ms provided the optimum parameters for high sensitivity, together with sufficient data points per peak (≥15) for improved reproducibility. In addition to chromatographic retention times, method selectivity was achieved via applying high resolution accurate mass with low mass tolerance filter (<5 ppm) for identification of each target compound. Six-point linear calibration curves (R² > 0.95) were established for all target analytes over a concentration range of 1-1500 ng/ml. Good results were obtained for method accuracy (% recovery = 76-104%), inter- and intra-day precision (relative standard deviation <15%) at 3 concentration levels. Instrumental detection and quantification limits ranged from (0.02-1.21 ng/ml) and (0.07-4.05 ng/ml), respectively. While optimised MS/MS analysis through parallel reaction monitoring (PRM) mode provided slightly higher sensitivity, Full scan MS mode allowed for higher mass resolution (selectivity), more data points per peak (reproducibility) and more importantly, the potential for post-acquisition screening of non-target compounds. Following solid phase extraction (SPE) of target analytes, the method was successfully applied to provide first data on PPCPs occurrence in effluent and surface water samples (n = 10) from Egypt. Moreover, screening for non-target compounds revealed the presence of bisphenol A, which was further confirmed via matching with an authentic standard. Overall, this study provides first insight into the high analytical capabilities of the Q-Exactive™ Orbitrap platform for both targeted/non-targeted analysis of PPCPs in environmental matrices.

Keywords: Effluent; Egypt; Non-target screening; Pharmaceuticals and personal care products; Q Exactive Orbitrap; Surface water.