Quantification of Linagliptin by Chemical Derivatization with Appliance of Chromogenic Reagents

Two simple, specific, accurate, precise, sensitive and cost effectivespectrophotometric methods have been developed and validated for quantification oflinagliptin in pure form and pharmaceutical formulations. Method A is established onthe computation of absorbance of purple coloured chromogen complex at 463 nmwhich is formed by the condensation reaction of the primary amine group oflinagliptin with vanillin (Schiff base formation). Method B is established oncomputation of absorbance of orange coloured chromogen at 454 nm which is formedby the condensation reaction of the primary amino group of linagliptin with NQS(1,2-naphtho quinine 4- sulphonic acid sodium salt) reagent. Two methods executedlinearity in the concentration range of 2.5-20 µg/ml and 10-90 µg/ml for method Aand B respectively. Linear relationship with good correlation coefficients of 0.998 and0.995 were monitored between absorbance and corresponding concentrations of linagliptin in vanillin and NQS respectively. The limit of detection, limit of quantification, molar absorptivity, sandell’s sensitivity and ring born concentration values were determined for the two spectrophotometric methods. The contemplatedmethods were validated statistically as per ICH guidelines. The reliability of both themethods is further ascertained by performing recovery tests by standard additionmethod. No significant interference was inspected from the excipients commonlyused as pharmaceutical aids with the assay procedure. The contemplated methodswere simple, sensitive, specific and can be successfully employed in routine analysisof linagliptin in pharmaceutical dosage forms.