Diffusive gradient in thin film (DGT) samplers have been widely used as water quality monitoring tools to study cationic trace metals of the Water Framework Directive (WFD) (lead, cadmium, nickel). However, these samplers based on a polyacrylamide diffusive gel and a Chelex resin do not allow trapping methylmercury (MeHg) and inorganic mercury [Hg(II)] which is also a priority substance of the WFD. The most common DGTs developed for these two mercury species are based on a 3-mercaptopropyl functionalized silica gel (3M) resin, with a diffusive gel either in polyacrylamide or in agarose. However, previous studies focused on the application of such DGTs in relatively contaminated surface waters (total Hg in dissolved phase HgTD >5 ng/L or MeHg in dissolved phase MeHgTD >0.25 ng/L). The aim of this study was to develop a home-made passive sampler combined with analysis by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) to measure low levels of mercury species in surface waters. Consequently, our work first focused on the control of Hg contamination mainly via the control of blank DGT. Then, we developed an analytical method coupling isotopic dilution with GC-ICP-MS, which allowed the extraction, derivatization and quantification of the mass of Hg(II) and MeHg trapped by the home-made/3M DGT at environmental levels. For in-situ validation, triplicates of home-made samplers were deployed at three sites in a low contaminated river (HgTD~0.5 ng/L), and we assessed time-weighted average concentrations (TWAC) for labile HgTD and MeHgTD. Our home-made/3M DGT resins contained significantly lower level of total Hg (HgTOT)