SPECTROPHOTOMETRIC DETERMINATION OF MICROQUANTITIES OF CARBIDOPA USING THE CARBIDOPA-IRON(III)-PHENYLFLUORONE TERNARY COMPLEX IN MICELLAR MEDIUM

A new analytical method for the spectrophotometric determination of Carbidopa (CBDA), either in pure form or in tablets is described. The method is based on a ternary complex formation between CBDA, iron(III) and phenylfluorone (Phfl) in the presence of Tween 20 as a surfactant. At the optimum pH 9.55, the ternary complex shows an absorption maximum at lambda = 636 nm, with an apparent molar absorptivity of 1.098 x 10(5) l mol-1 cm-1 and a Sandell's sensitivity of 2.22 ng cm-2. The solution of the ternary complex obeys Beer's law in the concentration range of 0.1-3.0 ppm of CBDA. The correlation coefficient was found to be r = 0.9999. Results obtained by application of the proposed method and the B. P. 1988 official one were in good agreement and a statistical comparison by means of the Student's t-test as well as by the variance ratio F-test shows no significant difference between the two analytical methods.