Simultaneous Determination of Pharmaceuticals by Solid-phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry: A Case Study from Sharjah Sewage Treatment Plant.

Mohammad Semreen,Xuelian Bai,Lucy Semerjian,Abdallah Shanableh,Kumud Acharya,Hasan Alniss,Mouath Mousa

doi:10.3390/molecules24030633

Abstract

The present work describes the optimization and validation of a highly selective and sensitive analytical method using solid phase extraction and liquid chromatography tandem mass spectrometry (SPE LC-MS/MS) for the determination of some frequently prescribed pharmaceuticals in urban wastewater received and treated by Sharjah sewage treatment plant (STP). The extraction efficiency of different SPE cartridges was tested and the simultaneous extraction of pharmaceuticals was successfully accomplished using hydrophilic-lipophilic-balanced reversed phase Waters® Oasis HLB cartridge (200 mg/ 6 mL) at pH 3. The analytes were separated on an Aquity BEH C18 column (1.7 µm, 2.1 mm × 150 mm) using gradient elution and mass spectrometric analysis were performed in multiple reactions monitoring (MRM) selecting two precursor ions to produce ion transition for each pharmaceutical using positive electrospray ionization (+ESI) mode. The correlation coefficient values in the linear calibration plot for each target compound exceeded 0.99 and the recovery percentages of the investigated pharmaceuticals were more than 84%. Limit of detection (LOD) varied between 0.1–1.5 ng/L and limit of quantification (LOQ) was 0.3–5 ng/L for all analytes. The precision of the method was calculated as the relative standard deviation (RSD%) of replicate measurements and was found to be in the ranges of 2.2% to 7.7% and 2.2% to 8.6% for inter and intra-day analysis, respectively. All of the obtained validation parameters satisfied the requirements and guidelines of analytical method validation.

Highlights

As population growth rate escalates, greater demand is being placed on securing adequate water supply, and greater challenges arise in purifying wastewaters for reuse
All parameters; mainly the type of solid phase extraction (SPE) cartridges and the pH of sample used to elute the pharmaceuticals under investigation were optimized to find the best extraction efficiencies for the target pharmaceuticals
The extraction efficiency results of the Oasis MAX were better than ENVI-C18 in all cases; the recovery results of the Oasis HLB were much better for the selected pharmaceuticals (Figure 1A,B)

Summary

Introduction

As population growth rate escalates, greater demand is being placed on securing adequate water supply, and greater challenges arise in purifying wastewaters for reuse. Local wastewater reuse regulations focus on conventional contaminants, such as biochemical oxygen demand (BOD5 ), chemical oxygen demand (COD), total suspended solids (TSS), nitrogen (N), phosphorus (P), total dissolved solids (TDS), and pathogens, but neglect emerging contaminants of concern (ECC) [11]. This necessitates the need to determine the behavior and regulate the concentrations of pharmaceutical contaminants during water recycling and reuse to safeguard public health and the environment as well as to reduce impediments to public acceptance of such alternative water management strategies. The assessment of environmental and human risk of ECC in UAE is not well-established

Methods

Results

Conclusion