Determination of Benzocaine and Tricaine in Fish Fillets Using BIA with Amperometric Detection

A system based on batch injection analysis (BIA) associated with amperometric detection at screen‐printed carbon electrode was used for the precise and rapid quantification of the anesthetics compounds benzocaine and tricaine in fresh fish fillets. Along this study, the best conditions for the BIA‐amperometry system were stablished for the rapid determination of these compounds. The results obtained demonstrate that the proposed method is an interesting alternative to the chromatographic methods, once it allows to perform rapid analysis (more than 300 injections per hour) with low limits of detection (3.02×10⁻⁸ mol L⁻¹ for benzocaine and 3.19×10⁻⁸ mol L⁻¹ for tricaine), using just 80 μL of sample for each analysis. Furthermore, it was possible to obtain high repeatability for both compounds analyzed, demonstrating good performance. The simple sample preparation developed in this study drastically reduced the amount of fat in the fish extract, favoring precision, as shown by the results of the recovery studies of both anesthetics contained in the fish samples (values above 99 % for both analytes).     

苯佐卡因的改进合成——推荐一个环保的多步合成实验

使用三氯异氰尿酸和2,2,6,6-四甲基哌啶-1-氧化物(TEMPO)共氧化体系替代经典的铬酸氧化体系完成苯佐卡因的合成,避免了铬酸氧化体系毒性大、污染大、后处理困难等不利于环保的因素。共氧化体系安全、环保,具有反应产率高、反应时间短、反应条件温和、实验现象明显和易操作等特点。     

Physicochemical characterization of drug-cyclodextrin complexes prepared by supercritical carbon dioxide and by conventional techniques

The objective of this study was to investigate the effectiveness of supercritical carbon dioxide (SC CO₂) technique for preparing solid complexes between β-cyclodextrin and three local anesthetic agents (benzocaine, bupivacaine, and mepivacaine) by comparing it to more traditional methods such as kneading, co-evaporation, co-grinding, and sealed-heating. Effects of variation of experimental conditions, i.e. temperature, pressure and exposure time, on the products prepared by SC CO₂ method were also examined. The products obtained were characterized by powder X-ray diffractometry and Fourier transform infrared spectroscopy, and tested for dissolution properties. Results suggested the possibility of complex formation between β-cyclodextrin and the three anesthetic agents, and indicated that it was influenced by the preparation technique. The co-grinding method was the only one resulting in completely amorphous products for all three drugs. Almost amorphous products, with only limited residual crystallinity, were obtained by co-evaporation and kneading techniques, while SC CO₂ and sealed-heating methods gave rise to more crystalline systems. As for the SC CO₂ method, temperature (for benzocaine and bupivacaine) or exposure time (for mepivacaine) had significant effects on the solid-state properties of the final products. Dissolution studies indicated that all the examined methods were more effective than the simple physical mixing in improving drug dissolution properties, but the different rank orders observed for the different drugs suggested that there is no general rule for the selection of the most effective preparation method, which depends on the type of drug-Cyd system considered. Nevertheless, in all cases, products obtained by the SC CO₂ method showed satisfactory dissolution properties.