A new spectrophotometric method was developed for the determination of aminomethylbenzoic acid （PAMBA） using 7,7,8,8-tetracyanoquinodimethane （TCNQ）. The method was based on the formation of charge transfer （CT） complex of this drug as n-electron donor with the n-acceptor TCNQ. TCNQ was found to react with PAMBA to produce a kind of yellow complex. The CT reaction proceeded quantitatively in pH 8.5 buffer solution. Different variables affecting the reaction were carefully studied and optimized. Under optimal reaction conditions, the stoichiometric ratio of the reaction, maximum absorption wavelength and the value of molar absorptivity were measured to be 1 ： 1, 425 nm, and 1.9 × 10^4 L.mol ^-1.cm^-1, respectively. Beer＇s law was obeyed in the range of 1- 9 μgomL-1 of PAMBA. The data have been filled to a linear regression equation A= -0.2612＋0.1123c （μgomL^-1）, with a correlation coefficient of 0.9996. The detection limit was 0.4 μg·mL^-1, R,S.D. was less than 1.9%, and average recovery was over 97.6%. The formation of the CT complex was also confirmed by both infrared and 1H NMR measurements. The thermodynamic property, kinetic property and reaction mechanism have also been discussed. The method developed was applied successfully to the determination of the subject drug in its pharmaceutical dosage forms with good precision and accuracy compared to official method revealed by t- and F-tests.
研究了在氧气存在下生物质催化氧化制甲酸体系中甲酸的稳定性,主要考察了反应温度、反应时间、氧气初始压力、硫酸浓度、催化剂等因素对于甲酸分解的影响。研究结果表明,温度、反应时间、硫酸浓度对甲酸的分解速率有显著的影响;氧气的初始压力对于甲酸的分解影响较小;催化剂NaVO3的存在会加速甲酸的分解。生物质催化氧化体系中,甲酸的分解反应为二级反应,甲酸分解反应的表观活化能为85.1 k J/mol。提出了在H2SO4溶液中氧气气氛下NaVO3催化甲酸分解的机理。
