Spectrophotometric determination of glimepiride in pharmaceutical preparations based on the formation of charge-transfer and ion-pair complexes

Two rapid, simple, accurate and sensitive spectrophotometric methods were developed for the determination of glimepiride in pharmaceutical preparations. The first method was based on the formation of a charge-transfer complex of the drug, as n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as π-acceptor. The second method was based on the formation of ion-pair complexes between the examined drug and bromothymol blue (BTB). The proposed methods were validated for linearity, limit of detection, limit of quantification, precision, accuracy, robustness and specificity. The calibration was linear over the concentration range of 10–80 and 20–120 μg/mL for methods I and II, respectively. The limits of detection were 2.6 and 2.8 μg/mL. The proposed methods were applied to the determination of the drug in pharmaceutical preparations. The results obtained were in good agreement with those obtained using the reference method (HPLC). There was no significant difference in the accuracy and precision as revealed by the accepted values of t- and F-tests, respectively.