Analytical method development for ultra-trace determination of human pharmaceuticals in aqueous samples. Assessing the performance of a sewage treatment plant

Abstract: Research focus in environmental pollution has recently been extended from more classical environmental pollutants such as PCBs or pesticides to pharmaceuticals and steroid hormones, which are designed to be biologically active and enter the environment primarily through regular domestic use. Consequently, it is important to monitor these substances concentrations in the effluents of sewage treatment plants (STPs) and in the environment in order to evaluate their associated risks. Moreover, the study of the occurrence and fate of these compounds within the STP would aid in improving their removal. Therefore, in this thesis the occurrence of seven pharmaceuticals (ibuprofen, naproxen, diclofenac, fluoxetine, ofloxacin, norfloxacin, ciprofloxacin), two metabolites (norfloxacin, clofibric acid), one toxic degradation product (4-isobutylacetophenone) and three steroid hormones (ethinylestradiol, estradiol, estrone) and their removal rates were investigated in a tertiary STP in the south of Sweden. Perspectives on sample preparation for the analysis of pharmaceuticals and steroid hormones in wastewater are presented. In this thesis, special attention is devoted toward the development of various sample preparation methodologies preceding the final separation and detection systems, liquid or gas chromatography coupled to DAD or MS. Solid-phase extraction (SPE) is widely used to extract polar compounds such as pharmaceuticals and personal care products (PPCPs). Different SPE sorbents were compared showing that hydrophilic-lipophilic balance (HLB) polymer has a higher trapping capacity than ion-exchange sorbents, but lacks high selectivity leading to large matrix effects in LC-ESI-MS/MS. Furthermore a molecularly imprinted polymer (MIP) based SPE was developed for non-steroidal antiinflamaroty drugs (NSAIDs) and clofibric acid extraction from wastewater resulting in no appreciable matrix effect. Membrane-based extraction techniques were as well evaluated for the extraction of steroid hormones, basic drugs and a toxic degradation product of ibuprofen. These methodologies had the advantage of simplicity, low cost and high enrichment factors. Finally these methods were applied to study the occurrence and removal rates of the target analytes at Kristianstad´s STP. Results showed that removal rates were above 90%, except for diclofenac, clofibric acid, estrone and ofloxacin. For the first time 4-isobutylacetophenone (4-IBAP) has been monitored along a STP. Relatively high concentrations of 4-IBAP were observed in the inlet of the STP, but since good removal rates were obtained during the biological step, as for many other drugs, it was not detected in the effluent.