In this study, new and efficient method, magnetic solid phase extraction coupled with dispersive liquid-liquid microextracton (MSPE-DLLME) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the preconcentration and determination of permethrin and deltamethrin in water samples. Several factors influencing the extraction efficiency including amount of sorbent, sorption time, type of extraction solvent and its volume, type of disperser solvent and its volume and elution time were investigated and optimized. Using optimum extraction conditions, dynamic linear range of 0.5-100 L-1 for both, limits of quantification (LOQs) of 0.6 L-1 for both and limits of detection (LODs) of 0.01 L-1 for both were obtained. Finally, the method was successfully applied for the extraction and determination of permethrin and deltamethrin in water samples in the range of micrograms per litre with RSDs < 4 %.

<p>In this study, simple and efficient ultrasound-assisted emulsification microextraction (USAEME) based on applying low density organic solvents combined with gas chromatography-flame ionization detector (GC-FID) was developed for the preconcentration and determination of mononitrotoluenes (MNTs) in water samples. In this method, the fine droplets of toluene were formed and dispersed in the sample with the help of ultrasonic waves which accelerated the formation of the fine cloudy solution without using disperser solvents. Several factors influencing the extraction efficiency such as the nature and volume of organic solvent, extraction temperature, ionic strength and centrifugation time were investigated and optimized. Using optimum extraction conditions, dynamic linear ranges of 0.5-500 μg L^-1, and limit of detections (LOD) of 0.3 μg L^-1 were obtained for o-nitrotoluene, m-nitrotoluene and p-nitrotoluene. Finally, the method was successfully applied to the extraction and determination of MNTs in the water samples in the range of micrograms <italic>per</italic> liter with relative standard deviations (RSD) < 12%.</p>

Um método novo foi desenvolvido para pré-concentração e determinação de compostos de ecstasy, 3,4-metilenodioxiamfetamina (MDA), 3,4-metilenodioximetilamfetamina (MDMA), 3,4-metilenodioxietilamfetamina (MDEA) e 3,4-metilenodioxipropilamfetamina (MDPA), em amostras de urina utilizando microextração líquido-líquido dispersiva (DLLME) e cromatografia gasosa com detector por ionização em chama (GC-FID). O método foi baseado na formação de gotículas de um extratante orgânico em soluções preparadas utilizando água, solvente orgânico imiscível (CS2) dissolvido em solvente dispersor miscível em água (acetona). A fase orgânica, que extraiu MDA, MDEA, MDMA e MDPA da solução da amostra preparada, foi separada por centrifugação. Parâmetros que afetam a eficiência da extração foram investigados e otimizados. Sob condições ideais, as linearidades do método foram 1,0-500 µg L-1 para MDEA e MDPA e 2,5-500 µg L-1 para MDA e MDMA. Os limites de detecção (LOD, S/N = 3, razão sinal ruído) foram no intervo de 0,3 a 0,8 µg L-1. O método foi aplicado com sucesso na determinação de analitos em amostras de urina.

A new method was developed for preconcentration and determination of ecstasy compounds, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethylamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA) and 3,4-methylenedioxypropylamphetamine (MDPA), in urine samples using dispersive liquid-liquid microextraction (DLLME) and gas chromatography (GC) with flame ionization detection (GC-FID). The method was based on the formation of tiny droplets of an organic extractant in prepared sample solution using water, immiscible organic solvent (CS2) dissolved in water-miscible organic disperser solvent (acetone). The organic phase, which extracted MDA, MDEA, MDMA and MDPA from the prepared sample solution, was separated by centrifugation. Parameters affecting extraction efficiency were investigated and optimized. Under the optimum conditions, linearities of the method were 1.0-500 µg L-1 for MDEA and MDPA and 2.5-500 µg L-1 for MDA and MDMA. The limits of detection (LODs, S/N = 3, signal-to-noise ratio) were in the range from 0.3 to 0.8 µg L-1. The method was successfully applied to the determination of analytes in urine samples.