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Analytical Methods for Environmental Contaminants of Emerging Concern


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in the matrix composition and the sufficient concentration factor need to be achieved. Thus, the standard liquid-liquid and liquid-solid extraction is not suitable. Solid-phase extraction (SPE) is most popular for water samples, because of the high concentration factor and the exchange of the medium to organic solvent, which can be quickly evaporated and replaced into the derivatization reagent. Because of the low volume of derivatization reagent used (about 50–100 µL), the concentration factor can reach 20,000 for surface water samples for a 1–2 L volume sample. In comparison, in a case of LC/MS with about 1 mL of extract volume, a factor of 2,000 can be reached. The high concentration factor by SPE-GC/MS-based methods allows sub-traces of pharmaceuticals to be tracked in drinking and ground water [82]. The SPE is also normally applied for purification of extracts of biosolids and solids (for example for analysis of NSAIDs in mussel tissue [83]). The suppression/enhancing of the analyte signal by the matrix components (“matrix effect”) during SPE-GC/MS analysis is mainly connected with impurities accumulated in the injector and the start of the capillary column, rather than the impact on EI ionization [69], which is a crucial issue in the electrospray of LC/MS. Therefore, during analysis of pharmaceuticals by GC/MS in environmental samples, special attention needs to be given to lowering the interferents in the extract and purity of the GC system.