Quantification of Linagliptin by Chemical Derivatization with Appliance of Chromogenic Reagents

Two simple, specific, accurate, precise, sensitive and cost effective spectrophotometric methods have been developed and validated for quantification of linagliptin in pure form and pharmaceutical formulations. Method A is established on the computation of absorbance of purple coloured chromogen complex at 463 nm which is formed by the condensation reaction of the primary amine group of linagliptin with vanillin (Schiff base formation). Method B is established on computation of absorbance of orange coloured chromogen at 454 nm which is formed by the condensation reaction of the primary amino group of linagliptin with NQS (1,2-naphtho quinine 4- sulphonic acid sodium salt) reagent. Two methods executed linearity in the concentration range of 2.5-20 µg/ml and 10-90 µg/ml for method A and B respectively. Linear relationship with good correlation coefficients of 0.998 and 0.995 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 contemplated methods were validated statistically as per ICH guidelines. The reliability of both the methods is further ascertained by performing recovery tests by standard addition method. No significant interference was inspected from the excipients commonly used as pharmaceutical aids with the assay procedure. The contemplated methods were simple, sensitive, specific and can be successfully employed in routine analysis of linagliptin in pharmaceutical dosage forms.