Analytical methods for the determination of pharmaceuticals in aqueous environmental samples

Recently several methods have been developed for the determination of drugs and their metabolites in the lower ng/l range using solid phase extraction (SPE), derivatization, detection and confirmation by gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS or LC-electrospray tandem MS (LC-ES/MS/MS). A wide range of pharmaceuticals from different medicinal classes can be determined down to the lower ng/l range. Due to the basically elevated polarity of pharmaceuticals either analysis by LC-ES/MS/MS or an efficient derivatization prior to measurements by GC/MS are mostly essential. A direct comparison of GC/MS and LC-ES/MS/MS displayed that only the latter allows for the analysis of the extreme polar betablockers atenolol and sotalol due to an incomplete derivatization of the functional groups. Further; the relative standard deviation using LC-ES/MS/MS was lower. However, when analyzing highly contaminated samples such as sewage a suppression of the electrospray ionization is likely to occur. Thus, to guarantee accurate and reproducible data either an efficient clean-up step has to be included into the sample preparation or an appropriate surrogate standard has to be spiked prior to SPE enrichment. (C) 2001 Elsevier Science B.V. All rights reserved.