Studies on analysis of mixed anti-cold pharmaceutical preparations. IX. Application of countercurrent distribution method

Abstract

In Craig-type countercurrent distribution, total quantity or material (Z) can be estimated by the equation derived from binomial distribution : [numerical formula] where W1 W2 and W3 are the quantities of material in the peak tube and the one before and after the peak tube, respectively, K the partition coefficient, n the number of transfers, and γ the number of tubes. When binomial distribution can be approximated by normal distribution, Z can be estimated, independently of n, γ and K, by the following formula : [numerical formula] where Wmax is the quantity of material in the peak tube, Wa(1) and Wa(2) are the quantities of material in the tubes of a-th before and after the peak tube respectively. Partition coefficients of chlorpheniramine maleate, dihydrocodeine phosphate, dlmethylephedrine hydrochloride, caffeine and 2-hydroxypropyl-7-theophylline were investigated, examined in several solvent systems, and they were found to be quantitatively separated with 50 transfers. By means of countercurrent separation followed by calculation of the total quantities of ingredients with above-mentioned equations, satisfactory results were obtained in separatory determination of mixed anti-cold pharmaceutical preparations.