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A method based on headspace solid phase microextraction with a new fiber, coupled with gas chromatography-mass spectrometry was developed for the determination of NDELA in cosmetic samples. The fiber provides Lewis acid-base interaction between its surface and analyte functional groups. The fiber was prepared by grafting aluminum tri-tert-butoxide on the surface of a fused silica. The optimization of SPME conditions showed that NDELA can be most effectively extracted at 70°C, in 15 min, with a sample volume of 0.5 (Vs/Vt), stirring rate of 150 rpm, desorption time of 5 min, desorption temperature of 260°C and at 12.5% (w/w) concentration of NaCl. Under the optimized conditions, LOD of 1 μg Kg(-1) and a calibration curve with correlation coefficients greater than 0.9897 and a linearity range from 6 to 10000 μg Kg(-1) were obtained. The intra-day and inter-day precision and accuracy were evaluated at four concentration levels. All of the values for accuracy and precision were lower than the acceptable limit of 15%. The fiber to fiber repeatability was 8.7%. The method was applied for the analysis of real samples including hair shampoo, body shampoo, dishwashing liquid and hand washing liquid. Relative recoveries were achieved in the range of 95-99%., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A two-phase electromembrane extraction (EME) was developed and directly coupled with gas chromatography mass spectrometry (GC-MS) analysis. The proposed method was successfully applied to the simultaneous determination of imipramine, desipramine, citalopram and sertraline. The model compounds were extracted from neutral aqueous sample solutions into the organic phase filled in the lumen of the hollow fiber. This method was accomplished with 1-heptanol as organic phase, by means of 60 V applied voltage and with the extraction time of 15 min. Experiments reported recoveries in the range of 69-87% from 1.2 mL neutral sample solution. The compounds were quantified by GC-MS instrument, with acceptable linearity ranging from 1 to 500 ng mL(-1) (R(2) in the range of 0.989 to 0.998), and repeatability (RSD) ranging between 7.5 and 11.5% (n = 5). The estimated detection limits (S/N ratio of 3:1) were less than 0.25 ng mL(-1). This novel approach based on two-phase EME brought advantages such as simplicity, low-costing, low detection limit and fast extraction with a total analysis time less than 25 min. These experimental findings were highly interesting and demonstrated the possibility of solving ionic species in the organic phase at the presence of electrical potential., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A simple and sensitive method for determining anatoxin-a in aqueous samples was developed using solid-phase microextraction (SPME) and gas chromatography with mass spectrometry (GC-MS) detection. Three forms of polyaniline (PANI) films and a single form of polypyrrole (PPY) film were prepared and applied for SPME. The extraction properties of these films to anatoxin-a were examined and it was shown that leucoemeraldine form of PANI displayed a better selectivity to this compound. SPME conditions were optimized by selecting the appropriate extraction parameters, including type of coating (leucoemeraldine form of PANI at 32 microm thicknesses), salt concentration (10%, w/v), time of extraction (30 min) and stirring rate (1000 rpm). The calibration curve was linear in the range from 50 to 10,000 ng/ml, with the detection limit (S/N = 3) of 11.2 ng/ml. This method was successfully applied for the analysis of anatoxin-a in the cultured media of two species of cyanobacteria.