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

Abstract. 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 µg L-1 showing correlation coefficients (R2) ranged from 0.991 to 0.999. The limits of detection (LODs) were from 0.02 to 0.59 µg L-1, while the limits of quantification (LOQs) ranged from 0.07 to 1.80 µg 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.\r\n \r\nResumen. La presencia de farmacos, clasificados como contaminantes emergentes, en agua superficial, subterranea y potable, genera incertidumbre sobre las interacciones que podrian ocurrir con organismos acuaticos y los seres vivos. Por lo tanto, el monitoreo del agua residual hospitalaria es de gran importancia para identificar los principales productos farmaceuticos que podrian descargarse al sistema de alcantarillado municipal y por lo tanto, estar presentes en el agua a tratar en las plantas de tratamiento de agua residual (PTAR). Este trabajo describe la implementacion y validacion de un metodo analitico altamente selectivo y sensible utilizando extraccion en fase solida (SPE) y cromatografia liquida acoplada a espectrometria de masas tandem (LC-MS/MS) para la deteccion y cuantificacion de estos compuestos emergentes. Se empleo el metodo de extraccion en fase solida utilizando cartuchos Oasis HLB. Para el analisis LC-MS/MS, la separacion cromatografica se realizo en una columna Kinetex C-18 (Phenomenex), y la deteccion se realizo en un espectrometro de masas en tandem AB SCIEX QTrap 3200 (MS/MS) en el modo de monitoreo de reacciones multiples (MRM). El analisis cuantitativo se llevo a cabo utilizando el metodo de estandar interno (IS) con analogos marcados isotopicamente. El metodo presento una buena linealidad dentro del rango de concentracion de 0.1 a 400 µg L-1, con coeficientes de correlacion (R2) que oscilaron entre 0.991 y 0.999. Los limites de deteccion (LOD) fueron de 0.02 a 0.59 µg L-1, mientras que los limites de cuantificacion (LOQ) variaron de 0.07 a 1.80 µg L-1. El metodo analitico se aplico con exito al analisis de muestras de agua residual vertidas por un hospital publico de San Nicolas de los Garza, Nuevo Leon, Mexico, en dos periodos de muestreo: mayo de 2017 y marzo de 2018.