Spectrophotometric Determination of Pioglitazone Hydrochloride by Its Charge-Transfer Reaction with Ethyl Eosin

In an acetate buffer medium of pH 4.0,due to the charge transfer reaction,an ion association complex was formed between pioglitazone (PGTZ) and ethyl eosin (EE),leading to color-fading of EE.Linear relationship between the magnitude of decrease in absorbance and the concentration of PGTZ was kept in the range of 9.75×10-7-1.26×10-5mol·L-1 when measured at the wavelength of 516 nm.The apparent molar absorptivity (ε516) found was 6.44×104L·mol-1·cm-1,and detection limit (3s/k) of the method was found to be 3.25×10-7mol·L-1.Samples of tablets and capsules of pioglitazone hydrochloride were analyzed by the proposed method,and the amounts of PGTZ found were checked quite well with the labelled values and also with the results obtained by HPLC.Recovery and precision of the method were tested by the standard addition method using samples of human blood serum and urine as matrixes,values of recovery found were in the range of 97.7%-103.3%,and values of RSD′s (n=6) found were less than 2.5%.