Evaluation of sorption surface materials for reactive mercury compounds

Sorption surfaces are commonly used to collect atmospheric mercury compounds, with a range of materials used by the mercury research community that have different levels of performance. Here, five polymer-based membranes were loaded with ambient reactive mercury and compared to 2 widely used sorption surface materials: nylon and cation exchange membranes. Only 1 tested material, polyethersulfone, performed similarly to the cation exchange membrane; the remaining tested materials sorbed significantly less mercury, and many had significantly higher blank mercury amounts than the cation exchange membrane. Nylon was the only material that was compatible with thermal desorption analysis, as the remaining materials physically degraded or negatively affected the analyzer; however, nylon was not amenable for quantitative analyses under all ambient conditions. Additional testing of the nylon and cation exchange membrane demonstrated that ambient reactive mercury compounds were more stable on both materials than high concentrations of single-source gaseous oxidized mercury compounds. Single-source gaseous oxidized mercury compounds were significantly lost and/or transformed within less than 80 days of storage, whereas ambient reactive mercury compounds were stable on nylon and cation exchange membranes after 190 days of storage. However, minimizing sampling and storage duration, along with exposure of sampled membranes to ambient air, to reduce biasing results is prudent. •The Hg community is in need of surfaces that collect ambient reactive Hg (RM).•Of the materials studied, nylon and cation exchange membranes (CEM) were best.•RM is quantitatively retained on CEM after 6 months of storage.•RM compounds are not transformed on nylons during 6 months of storage.•Single-source oxidized Hg compounds are less stable on sorption surfaces than RM.