López Carreto M, Lunar L, Rubio S, Pérez-Bendito D
Department of Analytical Chemistry, Faculty of Sciences, University of Cordoba, Spain.
Analyst. 1996 Nov;121(11):1647-52. doi: 10.1039/an9962101647.
The kinetic wavelength-pair method was applied to the simultaneous determination of o-cresol and m-cresol, based on their oxidative coupling with aniline in the presence of hypochlorite as oxidant and nitroprusside as catalyst. The benzoquinoneanils produced exhibited severe spectral overlap. Resolution of this isomer mixture by using discrete wavelengths was subject to a high degree of error for the determination of m-cresol since the ratios vo-cresol/vm-cresol (where v denotes initial rate for the oxidative coupling reaction) and epsilon o-cresol/epsilon m-cresol (where epsilon is the absorptivity of reaction products) were greater than unity at any given wavelength. Selectivity in the resolution was achieved by measuring the initial rate difference at the wavelength pair 666-566 nm where the contribution of o-cresol was removed, o-Cresol and m-cresol were simultaneously determined at mass ratios between 5:1 and 1:5 at concentrations from 1 to 5 micrograms ml-1, with relative standard deviations of less than 3%. The proposed method was applied to the determination of o-cresol and m-cresol in urine samples, with analytical recoveries ranging between 95 and 105%.
基于邻甲酚和间甲酚在次氯酸盐作为氧化剂、硝普钠作为催化剂存在的条件下与苯胺发生氧化偶联反应，采用动力学波长对法同时测定邻甲酚和间甲酚。所生成的苯醌苯胺显示出严重的光谱重叠。由于在任何给定波长下，邻甲酚的反应初始速率与间甲酚的反应初始速率之比（其中v表示氧化偶联反应的初始速率）以及邻甲酚与间甲酚的吸光系数之比（其中ε是反应产物的吸光系数）均大于1，因此使用离散波长对该异构体混合物进行分离时，测定间甲酚会存在高度误差。通过测量666 - 566 nm波长对处的初始速率差实现分离选择性，在此波长对处邻甲酚的贡献被消除，邻甲酚和间甲酚在质量比为5:1至1:5、浓度为1至5微克/毫升的范围内同时测定，相对标准偏差小于3%。该方法应用于尿样中邻甲酚和间甲酚的测定，分析回收率在95%至105%之间。
