RESUMO
Dipeptidyl peptidase-4 inhibitors, so-called gliptins, constitute a fairly novel class of oral hypoglycemic agents. The development and validation of an automated online SPE-LC-UV method to determine intact sitagliptin, saxagliptin, vildagliptin and metformin simultaneously in human urine samples were performed. For the two-dimensional chromatographic separation, a Gemini C18 (250.0 × 4.6 mm i.d., 110 A0, 5.0 µ) analytical column and a gradient elution with 10.0 mM o-phosphoric acid and methanol and for the online SPE analysis of urine samples, a LiChrospher® ADS SPE-column (20.0 mm × 2.0 mm i.d., 25.0 µm) were used through the study. The fractionation, transfer, elution and separation of the spiked urine samples were achieved in just 9.57 min runtime with 12.0 mL of solvent consumption which was green and economical compared to other sample preparation methods. The calibration curves were determined to be linear in a wide range of 0.10-100.00 µg/mL with satisfactory regression coefficients. Method developed for two-dimensional determination of gliptins would be useful as a reference in therapeutic drug monitoring and screening for forensic medical cases which involve the abuse, unintentional or misuse of multiple gliptins in terms of its practical use, easy detection and reliable results.