Elsevier

Analytica Chimica Acta

Volume 805, 17 December 2013, Pages 107-115
Analytica Chimica Acta

Quantitative on-line preconcentration-liquid chromatography coupled with tandem mass spectrometry method for the determination of pharmaceutical compounds in water

https://doi.org/10.1016/j.aca.2013.10.041Get rights and content

Highlights

  • A multi-residues method has been developed for 40 pharmaceuticals determination with on-line preconcentration coupled to LC–MS/MS.

  • Matrix effects have been studied for tap and surface waters.

  • Low quantification limits have been validated for environmental analysis.

  • A survey showed the presence of 16 pharmaceuticals in Isle River and their absence in drinking water.

Abstract

One of the current environmental issues concerns the presence and fate of pharmaceuticals in water bodies as these compounds may represent a potential environmental problem. The characterization of pharmaceutical contamination requires powerful analytical method able to quantify these pollutants at very low concentration (few ng L−1).

In this work, a multi-residue analytical methodology (on-line solid phase extraction-liquid chromatography–triple quadrupole mass spectrometry using positive and negative electrospray ionization) has been developed and validated for 40 multi-class pharmaceuticals and metabolites for tap and surface waters. This on-line SPE method was very convenient and efficient compared to classical off-line SPE method because of its shorter total run time including sample preparation and smaller sample volume (1 mL vs up to 1 L). The optimized method included several therapeutic classes as lipid regulators, antibiotics, beta-blockers, non-steroidal anti-inflammatories, antineoplastic, etc., with various physicochemical properties. Quantification has been achieved with the internal standards. The limits of detection are between 0.7 and 15 ng L−1 for drinking waters and 2–15 ng L−1 for surface waters. The inter-day precision values are below 20% for each studied level.

The improvement and strength of the analytical method has been verified along a monitoring of these 40 pharmaceuticals in Isle River, a French stream located in the South West of France. During this survey, 16 pharmaceutical compounds have been detected.

Introduction

Because of a continuous increasing consumption of pharmaceuticals, the problem of their presence in the environment and more particularly in water bodies is a serious environmental issue in France, and on wider scale, in industrialized countries. Most of pharmaceuticals are used for several decades but scientific studies dealing with this problem have been published in the last 15 years mainly related to the increase of analytical methodology performance [1], [2], [3]. The toxicity of these molecules, initially designed with biological effects for people or animals, may have a chronic impact on aquatic living organisms. Actually, the continuous presence of pharmaceuticals in water bodies even at very low concentration, can lead to unwanted biological effects on aquatic species. Pharmaceuticals are continuously released in natural waters via wastewater treatment plants but also hospitals, industrials, households and farming [4]. It is therefore of great concern to try to broaden the current knowledge and to determine the impact of pharmaceutical pollution on the environment.

Several surveys highlight the occurrence of pharmaceutical residues in the aquatic and terrestrial compartments [[5], [6] for example]. The low concentrations usually determined in natural waters require the development of sensitive analytical methodologies, adapted to environmental matrices able to quantify pharmaceuticals at ng L−1 level or less. Analytical methods mainly consist in multi-residue methods, with mass spectrometry coupled to chromatographic techniques (gas [7], [8], [9], [10] or liquid [11], [12], [13], [14], [15]). An extraction-concentration step is necessary prior to chromatographic analysis. Nowadays, the extraction step is commonly performed with an off-line solid phase extraction procedure to be specific and sensitive enough. However, more recently, the development of on-line solid phase extraction with new commercially available apparatus has been proposed [16], [17], [18].

Two different approaches of on-line extraction have been described in the literature. The first set consists in small columns that can be used several times and the second one is similar to off-line usual solid phase extraction with single use cartridges [19]. This technique was firstly applied for pesticides in waters [20], [21] and recently extended for pharmaceuticals. On-line methods have initially been developed for the quantification of few compounds (<10) [16], [22], [23]. With further development, methods have been proposed for multi-class analyses [24], [25], [26]. By comparison with off-line solid phase extraction, these methods are less time consuming and require a lower volume of sample. On-line methods are therefore financially more attractive than off-line methods as demonstrated by Trenhold et al. [18].

The aim of this work is to develop and to validate a sensitive and specific multi-residue method using on-line preconcentration-liquid chromatography–tandem mass spectrometry. The interest is to analyze a wide number of compounds with various physicochemical properties in very short time compared to the laborious off-line SPE. On-line analytical methods combining SPE and LC–MS/MS have already been reported for the determination of a broad range of pharmaceuticals (e.g. Ref. [26] for more than 40 compounds). However, these methods used an automated SPE system similar to the classical off-line usual solid phase extraction with single use cartridges. EQuan™ system uses a multiple used column for preconcentration step which can be used up to 400 times and is completely automatized. EQuan™ system works with a low sample volume (<5 mL) and the automation make it an ideal method for the analysis of a large number of samples with a reduction of interferences during sample handling and concentration. Moreover, on-line system can provide a significant advantage when crisis management following pollution is concerned. Actually, the possibility of directly injecting samples will give a rapid qualitative result.

Our method has been validated for 40 pharmaceuticals from different therapeutic groups in tap and surface waters. Its performances have been evaluated under the most rigorous conditions to ensure higher reliability. The on-line method uncertainty for each compound has been determined using two different approaches. The method will therefore be applied to large-scale surveys.

Section snippets

Materials and reagents

Pharmaceutical standards (purity >97%) were purchased from Sigma-Aldrich (St Louis, MO, USA) except for monensin provided by Fischer Scientific France (Waltham, MA, USA). Quality control (QC) solution was supplied by Cluzeau Info Labo (Sainte-Foy-La-Grande, France). Isotopically labelled compounds were purchased from C/D/N Isotopes (Quebec, Canada) except for chloramphenicol d5 and sulfamethoxazole d4 which were from Dr Ehrenstorfer (Augsburg, Germany) and acetaminophen d4 from LGC Promochem

Loading time and flow rate of the preconcentration step

The optimal loading conditions of the sample have to be determined in a first step. Indeed, the nature of the solvent, the loading time and flow rate influence the retention of analytes onto the preconcentration column. The highest retention of compounds has to be reached and early desorption of analytes has to be avoided. Purified water, without any organic solvent, has been used as carrier solvent to insure a better retention of more polar compounds.

Flow rate and loading time optimization has

Conclusion

Through this study, a multi-residue method by on-line preconcentration has been developed and validated for 40 pharmaceutical residues in drinking and surface waters with a wide variety of physicochemical properties. The low sampling volume (<5 mL) as well as a relatively short time of preparation and of analysis (20 min for negative mode and 28 min for positive mode) including preconcentration step, elution and detection are among the most significant advantages of this system by comparison with

Acknowledgements

The authors thank the reviewers of the paper for their very helpful comments. The authors acknowledge financial support from FEDER (no. présage: 33086), Conseil Général de la Dordogne and Thermo Fisher Scientific. LPTC thanks Anses for financial support (Toxstep project EST-09-57). The authors would also like to thank Agence de l’Eau Adour Garonne and Lyonnaise des Eaux Périgueux for their different contributions. SI gratefully acknowledges ANRT (Agence Nationale pour la Recherche et la

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