Spectrofluorimetric determination of Alogliptin benzoate through condensation with ninhydrin and phenylacetaldehyde: application to dosage form and rat plasma

Alogliptin benzoate (ALG) is a dipeptidyl peptidase-4 inhibitor used to treat type 2 diabetes mellitus. In this study, a spectrofluorimetric method was developed for the derivatization of ALG to develop a fluorescent derivative. The derivatization reaction was carried out by reacting ALG with ninhydrin and phenylacetaldehyde in Teorell and Stenhagen buffer at pH 6.6. The reaction product was a fluorescent pyrrolidone derivative that was observed at λ_ex of 385 nm and λ_em of 475 nm. The effects of various experimental conditions on the derivatization reaction were investigated. The optimal conditions were found to be a reaction time of 15 min, a temperature of 80 °C, and a concentration of ninhydrin and phenylacetaldehyde of 1.4 mg mL⁻¹ and 0.028% v/v, respectively. A calibration plot was constructed in the concentration range of 20–460 ng mL⁻¹. The calibration curve had a high correlation coefficient of 0.9991 and a low detection limit of 6.57 ng mL⁻¹. The eco-scale penalty points for the derivatization method were calculated to be 86. This indicates that the method is environmentally friendly and has a low risk of generating harmful waste. The derivatization method described in this study provides a sensitive and green method for the quantification of ALG in pure form, dosage form, spiked and real rat plasma.