engleski

Comparison of Various Solid-Phase Extraction Materials for Sample Preparation of Veterinary Drugs from Water Samples

Pharmaceuticals are among the emerging microcontaminants in water because of concerns of their potential adverse effects on the ecosystem and possibly on human health. They are likely to be released into the aquatic environment via wastewater effluent and agricultural runoff as a result of incomplete metabolism, ineffective treatment removal or improper disposal because large quantities of antibiotics are used annually in human therapy and in agriculture. Problem is that veterinary drugs include antibiotics don’ t have resolved questions about maximal concentrations which can be released in rivers and other nature resources. To resolve this problem we have to understand their nature, which result from their chemical properties, and to establish the method for their identification and determination. Level of veterinary drugs in natural water is very low. Because of that, and because of complex matrix composition, the selected pharmaceuticals have to be preconcentrated and the sample cleaned out of the interfering ingredients. The analytical procedure for pharmaceutical analysis usually comprises the following steps: sampling, sample preparation and final determination. A number of papers describing analytical methodologies for the determination of pharmaceuticals in water and in other complex environmental matrices have been published recently. Sample preparation is necessary to isolate the desired components from complex matrices, because most analytical instruments cannot handle the matrix directly. Classical extraction procedures consume large amounts of solvents, thus themselves creating environmental and occupational hazards, and often provide very little selectivity. Analysts responded to this challenge by increasing research on sorbent traps, solid-phase extraction (SPE), solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE) as other, less-solvent-consuming, alternatives to charcoal tube, liquid-liquid, and Soxhlet extraction. At present, solid-phase extraction (SPE) has become an often-preferred preconcentration technique in the screening for a wide range of organic micropollutants in water. A wide choice of materials available on the market makes SPE a suitable tool to cope with an increasing variability of organic compounds entering the hydrosphere. However, the interactions of various sorbent materials with compounds having different physico-chemical properties leads inevitably to large differences in preconcentration efficiency. The key of the problem when applying SPE remains the method development and the primary decision for the analysts is the choice of the sorbent that is able to solve their trace-analysis problem. Method development being related to the properties of the analytes of interest, many aspects due to the various physico - chemical properties of compounds included in a multiresidue analysis have to be considered. The aim of this paper was to investigate the efficiency of preconcentration of eight selected organic compounds from aqueous solutions on various SPE materials. We use different types of cartridges (SDB-L, C18-E, Strata-X, Strata-X-C, C8, CN, SCX and SAX) which we obtained from Phenomenex. The studied compounds were enrofloxacine (ENRO), norfloxacine (NOR), oxytetracycline (OTC), trimethoprim (TMP), sulfadimidine, sulfadiazine, sulfaguanidine and penicillin G/procaine (PGP). Extraction efficiency was determined by thin-layer chromatography (TLC) using 0.05 M H2C2O4-methanol = 81:19 as developer on CN modified chromatographic plates. After development the plates were air dried and the pharmaceuticals were detected and quantified at 366 nm, with the exception of TMP, which was measured at 254 nm. Video densitometry was performed with highly sensitive 3CCD colour video camera HV-C20 (Hitachi, Denshi, Japan). The results obtained showed that most of the tested materials were suitable for sufficient preconcentration of a substantial part of the tested analytes. However, specific differences in recovery of one or more analytes were found for almost each sorbent even in the case when the materials had similar composition. This behaviour clearly indicates the need for a thorough testing of capabilities of any SPE material intended for the use in a wide range screening method for the identification of unknown organic micropollutants in water.

pharmaceuticals; solid-phase extraction (SPE); cartridges; thin-layer chromatography (TLC)

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