Determination of cefadroxil by three simple spectrophotometric methods using oxidative coupling reactions

Abstract

Three simple and sensitive visible spectrophotometric methods for the assay of cefadroxil have been developed. MethodA (λ_max 410 nm) is based on the reaction of cefadroxil with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the presence of eeric ammonium sulphate. MethodB (λ_max, 510 nm) involves the reaction with 4-aminophenazone in the presence of potassium hexacyanoferrate(III). MethodC (λ_max, 620 nm) involves reaction with 2, 6-dichloroquinone-4-chlorimide (Gibb's reagent). All variables have been optimised and the reaction mechanisms presented. Regression analysis of the Beer's plots showed good correlation in the concentration ranges 1.0–6.0, 2.0–24.0 and 1.0–6.0 μg/ml for methodsA, B andC, respectively. No interferences were observed from excipients and the validity of the methods was tested by analysing pharmaceutical dosage forms. Recoveries were 98.0–100.3%. The concentration measurements were reproducible within a relative standard deviation of 1.0%.