Electromembrane extraction using a polypropylene hollow fiber impregnated with 1‐ethyl‐2‐nitrobenzene was evaluated for the extraction and preconcentration of the fungicides thiabendazole and carbendazim from water samples before capillary electrophoresis analysis. The composition of the supported liquid membrane, the HCl concentration in the acceptor solution, and the stirring rate (of the donor solution) were optimized using the one‐variable‐at‐a‐time method. In contrast, a face‐centered central composition design was used for optimization of voltage, extraction time, and concentration of HCl in the donor solution. After optimization, electromembrane extraction provided enrichment factors of 50 and 26 for thiabendazole and carbendazim that allowed us to achieve limits of detection of 1.1 and 2.3 μg/L, respectively. Repeatability (intraday precision) expressed as the relative standard deviation varied from 2.5 to 2.8%, while the interday precision ranged from 3.1 to 3.3%. The proposed method was applied for analysis of samples of tap and river water, and acceptable precision and accuracy were attained.

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A novel, simple, and rapid method for the determination of the anesthetics benzocaine and lidocaine in pharmaceutical formulations using capillary electrophoresis with spectrophotometric detection (210 nm) is proposed. In this method, the sample preparation was fast and simple, using only aqueous dilution or extraction with sonication aid. A background electrolyte composed by 10 mmol L ‐1 of monosodium phosphate with pH 2.1 allowed the separation of the anesthetics with good peak resolution in less than 5 min. The limits of quantification were 0.31 and 0.68 mg L−1 for lidocaine and benzocaine, respectively. The intra‐ and inter‐day precisions (RSD%) ranged from 1.1 to 4.8% and the accuracies (as recovery percentage) varied from 84 to 109.4%. The proposed method was successfully applied for analyses of commercial samples of pharmaceutical formulations, such as otologic solution, ointment, and spray solution and lozenges for sore throat.

We propose a simple and fast method for the determination of the preservatives propionate and sorbate in bread using capillary electrophoresis with capacitively coupled contactless conductivity detection. The preservatives were quickly extracted from bread using ultra-pure water and ultrasonic energy. The separation of the analytes, with good resolution, was achieved in about 7 min. The proposed method showed good linearity with coefficients of determination > 0.99 for both the preservatives. The limits of quantification of the method were 0.11 and 0.21 g/kg for propionate and sorbate, respectively. The accuracy of the method was evaluated by recovery tests, and the obtained recoveries varied from 88 to 94% for sorbate and 86 to 102% for propionate. The proposed method was successfully applied for the determination of propionate and sorbate in commercial samples of sliced white bread.

In this work a simple and fast method is proposed for determination of preservatives in bread using capillary electrophoreis with UV detection. The proposed method was succesfully applied for quantification of sorbate and propionate in commercial samples of bread.