Determination of chiral pharmaceuticals and illicit drugs in wastewater and sludge using microwave assisted extraction, solid-phase extraction and chiral liquid chromatography coupled with tandem mass spectrometry

Sian E Evans,Paul Davies,Anneke Lubben,Barbara Kasprzyk-Hordern

doi:10.1016/j.aca.2015.03.039

Abstract

This is the first study presenting a multi-residue method allowing for comprehensive analysis of several chiral pharmacologically active compounds (cPACs) including beta-blockers, antidepressants and amphetamines in wastewater and digested sludge at the enantiomeric level. Analysis of both the liquid and solid matrices within wastewater treatment is crucial to being able to carry out mass balance within these systems. The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices. The method was successfully validated for 10 compounds within all three matrices (amphetamine, methamphetamine, MDMA, MDA, venlafaxine, desmethylvenlafaxine, citalopram, metoprolol, propranolol and sotalol), 7 compounds validated for the liquid matrices only (mirtazapine, salbutamol, fluoxetine, desmethylcitalopram, atenolol, ephedrine and pseudoephedrine) and 1 compound (alprenolol) passing the criteria for solid samples only. The method was then applied to wastewater samples; cPACs were found at concentration ranges in liquid matrices of: 1.7ngL−1 (metoprolol) – 1321ngL−1 (tramadol) in influent, <LOD (desmethylcitalopram and metoprolol) – 506ngL−1 in effluent, and in solid matrix digested sludge: 0.4ngg−1 (metoprolol) – 275ngg−1 (citalopram). Enantiomeric profiling revealed that studied compounds were present in analysed samples in non-racemic composition. Furthermore, enantiomeric composition of studied analytes differed in liquid and solid matrices. This demonstrates that not analysing the solid fraction of wastewater may lead to over-estimation of the removal rates of cPACs as well as possible misrepresentation of the enantiomeric fraction of the compounds as they leave the wastewater treatment plant. Consequently risks from cPACs entering the environment might be higher than anticipated.

Highlights

Developments in pharmacology and an ageing population have led to a steady increase in the prescription of pharmaceuticals worldwide
The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices
The method was applied to wastewater samples; chiral pharmacologically active compounds (cPACs) were found at concentration ranges in liquid matrices of: 1.7 ng LÀ1 – 1321 ng LÀ1 in influent,

Summary

Introduction

Developments in pharmacology and an ageing population have led to a steady increase in the prescription of pharmaceuticals worldwide. The data produced is often used to inform risk assessments [1,2] and develop and test prediction models [3]. These concentrate on pharmacologically active compounds (PACs) present in the aqueous matrix and they do not consider the fraction of PACs adsorbed on to the sediments and suspended solids which may still be bioavailable to organisms and/ or may desorb in the future, possibly due to a change in matrix or environmental conditions. Corresponding models have emerged to take into account this additional data [13]

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Conclusion