Argatroban monohydrate has been used as a thrombin-selective inhibitor in the thrombin assay of platelet poor plasma samples. It may be used as a standard in gradient reversed-phase liquid chromatography coupled with high-resolution multistage mass spectrometry (LC/HR-MSn) for photoproducts fragmentation analysis and as a thrombin inhibitor competitive assay with fullerene-based C60 nanoparticle (NPs).