Determination of Pharmaceuticals Discharged in Wastewater from a Public Hospital Using LC-MS/MS Technique

The presence of pharmaceuticals classified as emerging contaminants (EC) in surface water, groundwater, and drinking water generates uncertainty concerning the interactions that could be occurred with aquatic organisms and living beings. Thus, the monitoring of hospital wastewater is of great importance to identify the main classes of pharmaceuticals that could be discharged to the municipal sewage system and wastewater treatment plants (WWTPs). This work described the implementation and validation of a highly selective and sensitive analytical method using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the detection and quantification of these emerging compounds. The solid-phase extraction (SPE) method was employed using Oasis HLB cartridges. For LC-MS/MS analysis, the chromatographic separation was conducted in a C-18 Kinetex column (Phenomenex), and detection was achieved in an AB SCIEX QTrap 3200 tandem mass spectrometer (MS/MS) in the multiple reaction monitoring (MRM) mode. The quantitative analysis was performed by using the internal standard (IS) method with isotopically labeled analogs. The implemented method presented good linearity within the concentration range of 0.1-400 mu g L-1 showing correlation coefficients (R-2) ranged from 0.991 to 0.999. The limits of detection (LODs) were from 0.02 to 0.59 mu g L-1, while the limits of quantification (LOQs) ranged from 0.07 to 1.80 mu g L-1. The analytical method was successfully applied to the analysis of wastewater samples discharged by a public hospital in San Nicolas de los Garza, Nuevo Leon, Mexico, in two sampling periods: May 2017 and March 2018.