Evaluation and optimization of solid adsorbents for the sampling of gaseous methylated mercury species

• Mono- (MMHg) and dimethylmercury (DMHg) were sampled from large volumes of air.
• Tenax®TA, Carbotrap®B, Bond Elut ENV were evaluated for MMHg collection and storage.
• Bond Elut ENV allows simultaneous collection of DMHg and MMHg from large air volumes.
• Bond Elut ENV is most suitable for MMHg determination using purge-and-trap methods.
• Lowering adsorbents temperature to 4 °C significantly improved collection efficiency.

This study evaluates the suitability of commercially available adsorbents for the measurement of gaseous organic mercury species namely monomethylmercury (MMHg) and dimethylmercury (DMHg).Bond Elut ENV (BE), a new generation of divinylbenzene (DVB), is evaluated the first time for simultaneous sampling and quantification of ultra-trace levels of MMHg and DMHg in air and its performance compared against Carbotrap® B (CB) and Tenax® TA (TA), two commonly used adsorbents for mercury solid phase adsorption.The suitability of TA as an absorbent for MMHg (recovery 100 ± 8.1%) but less so for DMHg (recovery 64 ± 17.3%) was confirmed while the reverse was observed for CB with an average recovery of 100 ± 0.3% for DMHg but only 61 ± 32.5% for MMHg. BE is the only adsorbent that showed excellent performance for trapping both Hg species with recoveries of 98 ± 9.2% and 95 ± 8.1% for MMHg and DMHg, respectively. Furthermore, BE exhibited much higher sampling capacities (>100 L at 4 °C) and preservation of sample integrity (>1 month at −20 °C in the dark).Overall, BE proves to be the most suitable adsorbent for simultaneous trapping of organic Hg species with high sampling capacity and sample stability but also very good chromatographic properties which are desirable characteristics for both collection traps and analytical traps. Bond Elut ENV is proposed as an alternative to both Tenax® TA and Carbotrap® B with additional advantages of offering more versatility and sampling options.

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