No abstract

We developed a simple microextraction method for extraction and pre-concentration of trace amounts of fluoroquinolones as polar model drugs in egg samples using an ionic surfactant. The present method, based on the use of silica-magnetite nanoparticles modified with anionic surfactant aggregates, was applied for determination of fluoroquinolones. The target analytes were converted into their ion pair complexes with dodecyl benzene sulphonic acid sodium (SDBS) and then extracted into an organic solvent. The factors influencing the extraction were investigated and optimized. Under optimum extraction conditions, a limit of detection (LOD) as small as 0.0029 mg L À1 and a linear dynamic range of 0.0083-0.166 mg L À1 were obtained for enrofloxacin in egg samples. The obtained results indicate that the proposed method is efficient, fast and inexpensive for extraction and determination of fluoroquinolones in real samples. a Linear dynamic range. b Correlation coefficient. c Limit of detection. d Limit of quantication. e Relative standard deviation (n ¼ 3). f Relative recovery. g Y and X are uorescence emission and concentration of the analytes (mg mL À1 ).This journal is

A sensitive technique to determinate naproxen in hair samples was developed using hollow-fiber micro-solid-phase combined with fluorescence spectrophotometry. The incorporation of multi-walled carbon nanotubes modified with a Keggin polyoxometalate into a silica matrix prepared by the sol-gel method was reported. In this research, the Keggin carbon nanotubes /silica composite was used in the pores and lumen of a hollow fiber as the hollow-fiber micro-solid-phase extraction device. The device was used for the microextraction of the analyte from hair and water samples under the optimized conditions. An orthogonal array experimental design with an OA24 (4(6) ) matrix was employed to optimize the conditions. The effect of six factors influencing the extraction efficiency was investigated: pH, salt, volume of donor and desorption phase, extraction and desorption time. The effect of each factor was estimated using individual contributions as response functions in the screening process. Analysis of variance was employed for estimating the main significant factors and their contributions in the extraction. Calibration curve plot displayed linearity over a range of 0.2-10 ng/mL with detection limits of 0.072 and 0.08 ng/mL for hair and aqueous samples, respectively. The relative recoveries in the hair and aqueous matrices ranged from 103-95%. The relative standard deviation for fiber-to-fiber repeatability was 3.9%.