Issopoulos P B, Economou P T
Department of Inorganic and Analytical Chemistry, University of Ioannina, Greece.
J Pharm Pharmacol. 1992 Dec;44(12):1020-2. doi: 10.1111/j.2042-7158.1992.tb07085.x.
A new high-sensitive spectrophotometric method for the determination of microquantities of carbidopa is described. The method is based on the reduction of neotetrazolium chloride by carbidopa in an alkaline ethanolic medium. The formazan formed exhibits an absorption maximum at lambda = 507 nm, with an apparent molar absorptivity of epsilon = 6.63 x 10(4) M-1 cm-1 and a corresponding Sandell's sensitivity of 3.68 ng cm-2. Beer's law is obeyed over the range of 0.10-6.0 micrograms mL-1 while the optimum concentration range is 0.125-5.0 micrograms mL-1. The regression line equation was calculated as: A = 0.271C + 0.0023 with a correlation coefficient of 1.0000 (n = 28). The accuracy and the precision of the method were considered as very satisfactory. The results obtained from the determination of carbidopa using both the described procedure and the corresponding USP. XXII and BP 1988 clinical methods were statistically compared by means of Student's t-test as well as by the variance ratio F-test, and no significant difference was observed.
本文描述了一种测定卡比多巴微量含量的新型高灵敏度分光光度法。该方法基于在碱性乙醇介质中卡比多巴对新氯化四氮唑的还原反应。生成的甲臜在λ = 507 nm处有最大吸收，表观摩尔吸光系数ε = 6.63×10⁴ M⁻¹ cm⁻¹，相应的桑德尔灵敏度为3.68 ng cm⁻²。在0.10 - 6.0微克/毫升范围内符合比尔定律，最佳浓度范围为0.125 - 5.0微克/毫升。回归线方程计算为：A = 0.271C + 0.0023，相关系数为1.0000（n = 28）。该方法的准确度和精密度被认为非常令人满意。使用所述方法以及相应的美国药典XXII和英国药典1988临床方法测定卡比多巴所得结果，通过学生t检验以及方差比F检验进行统计学比较，未观察到显著差异。
