Evaluation of a semi-permeable membrane device (SPMD) for passive sampling of solar filters from swimming pool waters and determination by HPLC-DAD.

Sunscreens are used to protect skin against ultraviolet radiation, avoiding the damages that can be caused by it. However, in vitro and in vivo studies report that some organic substances employed as sunscreens can alter the biological effects of several hormones. Therefore, a methodology for passive sampling using a semipermeable membrane device (SPMD) was developed for the extraction and preconcentration of some organic compounds employed in sunscreen formulations, such as benzophenone (BZP), 2-hydroxy-4-methoxybenzophenone (BZP-3), 3-(4-methylbenzylidene)-camphor (4-MBC), 2-ethylhexyl-4-methoxycinnamate (4-MCN), 2-ethylhexyl salicylate (EHS), and homomethyl salicylate (HMS), from swimming pool waters where exposure to these substances is unintended. The determination of these analytes in the acceptor phase was performed using high performance liquid chromatography with diode array detection (HPLC-DAD). The optimization of the methodology included the evaluation of several variables, such as type and volume of acceptor phase, dimensions and time of exposure of the SPMD, sample pH, and volume. The optimum conditions for the collection of the solar filters were achieved with an 8-cm device filled with 3.0 mL of acetonitrile and without adjustment of the sample pH, which was approximately 5.8. The collection time was 24 h. Afterwards, some parameters of merit of the developed method were determined. The working range for BZP, BZP-3, 4-MBC, 4-MCN, EHS, and HMS was established as 25-500 µg L-1. The methodological limits of detection and quantification for these analytes were 0.2-1.0 µg L-1 and 0.7-3.1 µg L-1, respectively. Quantification of the analytes was performed on four samples collected from different swimming pools. Recovery tests were performed with the samples spiked with 100 µg L-1 of each substance, and recovery percentages in the range of 75-116% were obtained. The performance of the SPMD was also verified through the determination of BZP-3, EHS, and HMS in a swimming pool water sample intentionally contaminated with a commercial sunscreen.

Spectrophotometric determination of rosuvastatin in pharmaceutical formulations using quinalizarin

ABSTRACT This work presents the development of a methodology based on the formation of a charge transfer complex between quinalizarin and rosuvastatin, allowing for the spectrophotometric determination of rosuvastatin at 579 nm. The factors involved in the sensitivity of the technique were studied (nature and proportion of the solvent, reaction time, pH of aqueous phase and quinalizarin concentration). The proposed spectrophotometric procedures were validated with respect to linearity, ranges, precision, accuracy, detection and quantification limits. Calibration curves of the formed color products showed good linear relationships over the concentration range of 6-15 mg L-1. The proposed method has been successfully applied, which can be confirmed by interference test (comparison between the standard curves and addition of analyte), method precision (RSD 2.3% to 6 mg L-1), and by accuracy (statistically equivalent results between the proposed method and a chromatographic method of reference).