engleski

Determination of pharmaceutical chemicals in the aquatic environment by gas chromatography/mass spectrometry

Pharmaceutical chemicals are a new class of emerging contaminants, which require an urgent environmental assessment. In the last few years, the number of reports in the literature expressing concern about possible environmental effects of various pharmaceutical chemicals is rapidly increasing (1). A wide variety of these highly biochemically active chemicals, including lipid regulating agents, antiphlogistics, betablockers, beta_2-symphatomimetics, psychiatric drugs, antiepileptic drugs, synthetic estrogens, and antibiotics, is used in human and veterinary medicine and subsequently released into the environment (1, 2, 3). The percentage of manufactured pharmaceuticals that are eventually excreted into the aquatic environment is dependent on their pharmacokinetics and therefore is very specific for individual drugs. The direct input of pharmaceuticals into the environment, such as wastewater discharge from manufacturing units and disposal of unused medications, can also be significant, especially at some hot-spots. Several reports indicated recently that pharmaceutical chemicals are rather common constituents of municipal wastewaters (2-5). Individual pharmaceutical compounds were detected in most of the examined municipal sewage effluents and polluted rivers with the maximum concentration values reaching microg/L-range. Landfill leachates were also shown to contain complex assemblages of pharmaceutical chemicals and their intermediates (6, 7). Since many of the disposal sites are open dumps without protective barriers and leachate collection systems, the infiltration of heavily contaminated leachates could seriously jeopardize the quality of groundwater near landfills (7). Several analytical techniques have been used for the determination of drugs and their metabolites, however, their analysis in environmental samples in the lower ng/l-range relies almost exclusively on hyphenated chromatographic techniques such as gas-chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). In order to achieve required detection limits in the ng/L-range as well as to separate target compounds from complex organic matrices, the analysis of aqueous samples includes regularly an enrichment step using solid phase extraction. Most of the pharmaceutical chemicals are relatively polar compounds, which reveal high solubility in water and low to moderate log K_ow values. The method of choice for most of the drugs is therefore LC/MS, while only neutral drugs can be analysed directly by GC/MS. Some more polar drug classes such as symphatomimetics and some analgesics can be analysed by GC/MS after derivatization (3, 4). Detection of drugs by common electron impact-MS and/or electrospray-MS provides usually a reliable confirmation of pharmaceutical compounds in environmental samples but it was shown that for some complex matrices such as wastewater and landfill leachates a more advanced MS/MS detection could be necessary. We have developed a specific method for determination of phenazone analgesics and caffeine in wastewater effluents and natural waters based on gas chromatography with mass selective detection. The method was applied to examine municipal wastewaters of several Croatian cities as well as to determine the impact of phenazone analgesics disposed on the main solid waste landfill of the city of Zagreb on underlying soil and groundwater below and near the landfill. It was shown that caffeine occurs in Croatian municipal wastewaters at a relatively uniformly high concentration (50-100 microg/L), while phenazone analgesics were found in rather low concentrations (<1 microg/L). In contrast, phenazone analgesics belong to the most abundant classes of anthropogenic compounds in the main landfill of the city of Zagreb. Qualitative analyses of solid waste and landfill leachates from the southeastern part of the landfill by GC/MS provided positive identification of three phenazone chemicals, including propyphenazone (PRO; 4-(1-methylethyl)-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one), aminopyrine (AM; 4-(dimethylamino)-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one), and antipyrine (ANT; 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one). The analyses of groundwater samples collected from the piezometers within and near the landfill area revealed that phenazone analgesics were present in significant concentrations. Propyphenazone was the prevailing compound in most of the analyzed samples, which clearly reflected its predominance in the landfill leachate. The concentration of propyphenazone in piezometers situated within the landfill was found typically in the range of 5-50 microg/L, which is the same order of magnitude as in the collected leachates. The concentration of aminopyrine varied widely from less 0.050 to 36 microg/L.

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