A rapid and sensitive analytical method for the determination of oxolinic acid and flumequine in aqueous samples based on dispersive liquid-liquid microextraction using ionic liquids (ILs) was developed. Based on the structural properties of the antibiotic agents studied, two ILs with different functionalities were required: ethyl-dimethyl-(2-methoxyethyl) ammonium tris(pentafluoroethyl)trifluorophosphate ([MOEDEA][FAP]) for extraction and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BFJ) to adjust the polarity of the medium. The significant experimental factors involved in DLLME were identified and optimized using the experimental design methodology. A Plackett-Burman design was initially used for screening, and a central composite design was used for optimization. The optimized method exhibited good precision, with relative standard deviation values of less than 5 % and limits of detections on the order of 0.1 and 0.3 ng mL-1 for the two drugs. The enrichment factors for both antibiotics were 13-33 fold. The proposed method was applied to the analysis of the two antibiotic in spiked surface, river, and wastewater samples.

Um método rápido e eficiente, baseado na integração da extração com solvente sob pressão (PSE) com limpeza através do método sólido de extração (SPE) e sistema de cromatografia gasosa com detector por captura de elétrons (GC-ECD) foi desenvolvido para a determinação de bifenilos policlorados (PCBs). Seis indicadores e doze PCBs semelhantes à dioxina foram selecionados como analitos. Este método baseia-se na integração da extração de solvente e de processos de limpeza no interior de uma célula pressurizada de aço inoxidável. As condições de extração otimizadas foram 6 min de extração, a 70 °C e dois ciclos de extração utilizando hexano/cloreto de metileno (1:1, v/v) como solvente de extração. Sílica gel acidificada com ácido sulfúrico foi utilizada para a limpeza integrada do extrato orgânico. Este método permite uma redução significativa no tempo de processo e o consumo de solvente. Repetibilidade, expressa como o desvio padrão relativo, variou de 3 a 6%, e a recuperação para a concentração de 20 ng g-1 variou entre 71 a 104%. O limite de detecção e quantificação variaram de 0,03 a 0,29 ng g-1 e 0,1 a 0,97 ng g-1, respectivamente. A variação linear foi entre 5 e 100 ng g-1. Finalmente, este novo método foi aplicado em amostras de carne de frango e de porco.

A rapid and efficient method based on the integration of pressurized solvent extraction (PSE) with solid phase extraction (SPE) cleanup and gas chromatography system with electron capture detection (GC-ECD) has been developed for determination of polychlorinated biphenyls (PCBs). Six indicators and twelve dioxin-like PCBs were selected as analytes. This method is based on the integration of solvent extraction and cleanup processes inside a pressurized stainless steel cell. The optimum extraction conditions were 6 min of extraction at 70 °C and two cycles of extraction using hexane/methylene chloride (1:1, v/v) as the extraction solvent. Silica gel acidified with sulfuric acid was used for integrated cleanup of the organic extract. This method allows a significant reduction in extraction time and solvent consumption. Repeatability, expressed as the relative standard deviation, ranged from 3 to 6%, and recoveries for concentration of 20 ng g-1 was ranged between 71 to 104% .The limit of detection and quantification ranged from 0.03 to 0.29 ng g-1 and 0.1 to 0.97 ng g-1 respectively. The linear range was between 5 and 100 ng g-1 . Finally this new method was applied to samples of chicken and pork.