Spectrophotometric study of ephedrine hydrochloride in drug using molecular absorption UV-Visible

A simple, rapid, accurate, and sensitive UV-Visible spectrophotometric method has been developed to estimate ephedrine hydrochloride (Eph) in pharmaceutical drugs. This method is based on preparing chelate complex through the reaction between Eph and cobalt ion (Co (II)). Ephedrine identification is done as an Eph - Co (II) complex after extraction by chloroform at λ max 389 nm. In this work, the optimum operation conditions such as pH, buffer volume, Co ion concentration, time of reaction and extraction, temperature, and water to organic volume ratio were determined. The linearity range of Eph has observed in the range between 1 and 80 ppm, at a wavelength of 387 nm with molar absorptivity range between 3.1867 × 103 to 1.6941 × 103(L·mol^-1·cm^-1) and metal to legend ratio of two. The results obtaind from this study are as follow: relative standard deviation (RSD) percentage is 0.303%, detection limit (D.L) = 0.94 ppm, Sandel's sensitivity (S) = 0.0135, relative error (Erel.) % = 0.039, recovery (Rec.) %=100.039. The results confirmed no interferences of excipients on the detection of Eph, and the proposed method has successfully applied for the determination of ephedrine-HCl in pure and pharmaceutical preparations. This method has several advantages, such as its low cost, high sensitivity, and ease of operation.