Functionalized graphene oxide tablets for sample preparation of drugs in biological fluids: Extraction of ritonavir, a HIV protease inhibitor, from human saliva and plasma using LC–MS/MS

Abstract

In this work, graphene oxide based tablets (GO-Tabs) were prepared by applying functionalized GO as a thin layer on a polyethylene substrate. The graphene oxide was functionalized with amine groups (-NH2 ) by Poly (ethylene glycol) bis(3-aminopropyl) terminated (GO-NH2 -PEG-NH2 ). The functionalized GO-Tabs were used for extraction of ritonavir in human saliva samples. The analysis of ritonavir in plasma and saliva samples was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gradient LC system with MS/MS in the positive ion mode (ESI+) was used. The transitions m/z 721→269.0 and m/z 614→421 were used for the ritonavir and the internal standard indinavir, respectively. In this study, the determination of the HIV protease inhibitor ritonavir in human saliva samples was carried out using functionalized GO-Tab and LC-MS/MS and the method was validated. Standard calibration curve for plasma and saliva samples was constructed from 5.0 to 2000 nmol L-1 . The limit of detection was 0.1 nmol L-1 and the limit of quantification was 5.0 nmol L-1 in both plasma and saliva matrices. The intra- and inter-assay precision values were found to be between 1.5 and 5.8%, and the accuracy values ranged from 88.0% to 108% utilizing saliva and plasma samples. The extraction recovery was over 80%, and the presented functionalized GO-Tabs could be re-used for more than ten extractions without deterioration in recovery.