engleski

Optimization of ultrasonic and microwave extraction of veterinary pharmaceuticals from sediment

Nowadays there is a growing concern about the effects of pharmaceuticals in the environment and many reports have been published on the occurrence, fate and risk assessment of veterinary drugs and other pharmaceuticals. Since most pharmaceuticals exhibit great chemical stability and high sorption coefficients in sediments and soils, they can accumulate in these solid environmental compartments and maintain detectable and biologically active concentrations for several months. Compared to water media soils and sediments have been scarcely investigated. Only few reports has been published on the potential contamination caused by these pharmaceuticals residues in sediments samples. To determine the levels at which pharmaceuticals accumulate in different environmental media and to study the cycle of veterinary drugs released in the environment, appropriate analytical methods are necessary. However, residue analysis in these complex samples requires, in addition to a sensitive chromatographic method, an extraction procedure that provides suitable recoveries for the analytes and a clean-up step to remove some of the co-extracted compounds. The objective of this research was to develope and optimizes a simple and effective sample preparation method for determination of selected pharmaceuticals in sediment samples. Pharmaceuticals investigated were: fluoroquinolone antibiotic ciprofloxacin, glucocorticosteroid dexamethasone, anthelmintic febantel, sulfonamide antibiotic sulfamethoxazole and their synergist trimethoprim. Sediments used for experimental work were from Birovača and Kupirovo in Lika, Croatia and had never been treated with any pharmaceuticals. Ultrasonic assisted extraction (UAE) and microwave accelerated extraction (MAE) were optimized to improve efficiency of the extraction process. Extraction procedures were optimized regarding time and temperature of extraction and solvent volume. Extraction efficiency for both extraction procedures, UAE and MAE, was determined by recovery experiments. The extracts were analyzed by high-performance liquid chromatography with diode array detector at 254 nm equipped with a C-18 column (Synergy Fusion 4µ ; m, 150 mm x 2 mm, Phenomenex). The mobile phase used was a mixture of 0.01 % formic acid in water and 0.01 % formic acid in acetonitrile at flow rate 1 mL/min with gradient elution. The injection volume was 30 µ ; L. The optimal conditions determined for UAE were 35 oC, solvent volume 20 mL of citric acid (pH=3.5) : acetonitrile = 20 : 80, (v/v) and extraction time 15 min at 600 W. The optimal conditions determined for MAE were 65 oC, solvent volume 15 mL of citric acid (pH=3.5) : acetonitrile = 20 : 80, (v/v) and extraction time 10 min at 600 W.

ultrasonic extraction; microwave extraction; veterinary pharmaceuticals; sediment

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