Trace determination of isoniazid at micro level using kinetic spectrophotometric method

An effective and fairly inexpensive spectrophotometric method for tracing the determination of isoniazid (INH) in pure form, as well as in pharmaceutical formulations, has been developed through the ligand substitution reaction between INH and aquapentacyanoruthenate (II) ion ([Ru(CN)5OH2]3-) in aqueous medium at ?max = 502 nm. The fixed time procedure has been employed under optimum reaction conditions. The calibration equations, relating absorbance measured at 502 nm at fixed times (tn = 2, 5 and 7 min) and cINH in linear range 1.37-27.43 ?g mL-1, were used for the trace determination of INH, which has been reported in the present investigation and are in agreement with official and reported methods. The percentage recovery has been calculated and found to be within the range of 99?101 % in the analysis of different pharmaceutical samples. The results reveal that the use of common recipients as the used additives do not produce any type of interference in the suggested method. The validity of the proposed method was also checked by statistical analysis which agreed with the results obtained using the official method. The present method is very simple, reproducible, sensitive and it can be adopted for trace determination of INH in different samples without using extracting agent.