Sensitive Simultaneous Measurement of Metformin and Linagliptin in Plasma Samples by Couple of Nano Graphene Oxide-based Dispersive Solid Phase Extraction Method and Liquid Chromatography

A simple, rapid, and ultra sensitive dispersive solid phase extraction based on nano graphene oxide was developed for simultaneous measurement of trace amounts of metformin (MET) and linagliptin (LIN) in plasma samples by HPLC-UV-Vis. Affecting factors on the extraction of these drugs, including adsorbent weight, extraction time, organic solvent type, desorption situations, and composition of solvent were examined and optimized. In optimum conditions, the LOD (limit of detection) and LOQ (limit of quantification) of the suggested technique were 2.0 ngmL-1 and 6.1 (ngmL-1) for LIN and 3.0 ngmL-1 and 9.2 ngmL-1 for MET, respectively. Suitable linear behavior in the considered ranges of concentration (10-2000 ngmL-1) and good correlation coefficient of 0.9901 and 0.9903 (r2) for LIN and MET were obtained, respectively. The RSD (relative standard deviations) according to three replicate measurements at 2, 20, 200 ngmL-1 levels of these drugs was less than 8.0%. In the last step, applicability of the suggested technique was examined by analyzing the drugs in plasma samples and reasonable results were achieved.