Influence of natural organic matter on the screening of pharmaceuticals in water by using liquid chromatography with full scan mass spectrometry

• Published in: Analytica chimica acta Vol. 700; no. 1; pp. 114 - 125
• Main Authors: Herrera Rivera, Zahira, Oosterink, Efraim, Rietveld, Luuk, Schoutsen, Frans, Stolker, Linda
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 26.08.2011; Elsevier
• Subjects: Accurate mass measurements; Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, High Pressure Liquid - methods; Databases, Factual; Dissolved natural organic matter; Drinking water treatment; Exact sciences and technology; High resolution; Linearity; Liquid chromatography; Mass spectrometry; Mass Spectrometry - instrumentation; Mass Spectrometry - methods; Non-target compounds; Organic Chemicals - chemistry; Other chromatographic methods; Pharmaceutical Preparations - analysis; Pharmaceutical Preparations - isolation & purification; Pharmaceuticals; Residues; Screening; Searching; Software; Spectrometric and optical methods; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - isolation & purification; Non-target compounds; Drinking water treatment; High resolution; Dissolved natural organic matter; Accurate mass measurements; Pharmaceuticals; Water; Organic matter; Selection; Lipids; Regulator; Dissolved organic carbon; Signal; Benzimidazole; Detection limit; Measurement error; Trace analysis; Correlation coefficient; Drug; Sulfonamide; Coupled method; Sample; Liquid chromatography; Concentration; Macrolide; Tetracycline; Screening; Sensitivity; Time of flight method; Residue; Linearity; Detection; Mass spectrometry; Effluent
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2010.12.040

The influence of natural organic matter on the screening of pharmaceuticals in water was determined by using high resolution liquid chromatography (HRLC) combined with full scan mass spectrometry (MS) techniques like time of flight (ToF) or Orbitrap MS. Water samples containing different amount of natural organic matter (NOM) and residues of a set of 11 pharmaceuticals were analyzed by using Exactive Orbitrap™ LC-MS. The samples were screened for residues of pharmaceuticals belonging to different classes like benzimidazoles, macrolides, penicillins, quinolones, sulfonamides, tetracyclines, tranquillizers, non-steroidal anti-inflammatory drugs (NSAIDs), anti-epileptics and lipid regulators. The method characteristics were established over a concentration range of 0.1–500 μg L −1. The 11 pharmaceuticals were added to two effluent and two influent water samples. The NOM concentration within the samples ranged from 2 to 8 mg L −1 of dissolved organic carbon. The HRLC-Exactive Orbitrap™ LC-MS system was set at a resolution of 50,000 (FWHM) and this selection was found sufficient for the detection of the list of pharmaceuticals. With this resolution setting, accurate mass measurements with errors below 2 ppm were found, despite of the NOM concentration of the different types of water samples. The linearities were acceptable with correlation coefficients greater than 0.95 for 30 of the 51 measured linearities. The limit of detection varies between 0.1 μg L −1and 100 μg L −1. It was demonstrated that sensitivity could be affected by matrix constituents in both directions of signal reduction or enhancement. Finally it was concluded that with direct shoot method used (no sample pretreatment) all compounds, were detected but LODs depend on matrix-analyte-concentration combination. No direct relation was observed between NOM concentration and method characteristics. For accurate quantification the use of internal standards and/or sample clean-up is necessary. The direct shoot method is only applicable for qualitative screening purposes. The use of full scan MS makes it possible to search for unknown contaminants. With the use of adequate software and a database containing more than 50,000 entries a tool is available to search for unknowns.