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The monitoring of low gaseous elemental mercury (GEM) concentrations in the atmosphere requires continuous high-resolution measurements and corresponding calibration capabilities. Currently, continuous calibration for GEM is still an issue at ambient concentrations (1–2 ngm-3). This paper presents a continuous flow calibration for GEM, traceable to NIST 3133 Standard Reference Material (SRM). This calibration approach was tested using a direct mercury analyser based on atomic absorption spectrometry with Zeeman background correction (Zeeman AAS). The produced continuous flow of GEM standard was obtained via the reduction of Hg2+ from liquid NIST 3133 SRM and used for the traceable calibration of the Zeeman AAS device. Measurements of atmospheric GEM using the calibrated Zeeman AAS were compared with two methods: (1) manual gold amalgamation atomic fluorescence spectrometry (AFS) calibrated with the chemical reduction of NIST 3133 and (2) automated gold amalgamation AFS calibrated using the mercury bell-jar syringe technique. The comparisons showed that a factory-calibrated Zeeman AAS device underestimates concentrations under 10 ngm-3 by up to 35 % relative to the two other methods of determination. However, when a calibration based on NIST 3133 SRM was used to perform a traceable calibration of the Zeeman AAS, the results were more comparable with other methods. The expanded relative combined uncertainty for the Zeeman AAS ranged from 8 % for measurements at the 40 ngm-3 level to 91.6 % for concentrations under 5 ngm-3 using the newly developed calibration system. High uncertainty for measurements performed under 5 ngm-3 was mainly due to instrument noise and concentration variation in the samples. [ABSTRACT FROM AUTHOR]

The monitoring of low gaseous elemental mercury (GEM) concentrations in the atmosphere requires continuous high-resolution measurements and corresponding calibration capabilities. Currently, continuous calibration for GEM is still an issue at ambient concentrations (1-2 ng m-3). This paper presents a continuous flow calibration for GEM, traceable to NIST 3133 Standard Reference Material (SRM). This calibration approach was tested using a direct mercury analyser based on atomic absorption spectrometry with Zeeman background correction (Zeeman AAS). The produced continuous flow of GEM standard was obtained through reduction of Hg2+ from liquid SRM NIST 3133 and used for traceable calibration of Zeeman AAS. Measurements of atmospheric GEM using the calibrated Zeeman AAS were compared with two methods: manual gold amalgamation atomic fluorescence spectrometry (AFS) calibrated with the chemical reduction of NIST 3133 and automated gold amalgamation AFS calibrated using the mercury bell-jar syringe technique. The comparisons showed that factorycalibrated Zeeman AAS underestimates concentrations under 10 ng m-3 by up to 35 % relative to the two other methods of determination. However, when a calibration based on SRM NIST 3133 was used to perform a traceable calibration of Zeeman AAS, the results were more comparable with other methods. The expanded relative combined uncertainty for Zeeman AAS ranged from 8 % for measurements at the 40 ng m-3 level to 91.6 % for concentrations under 5 ng m-3 using the newly developed calibration system. High uncertainty for measurements performed under 5 ng m-3 was due mainly to instrument noise and concentration variation in the samples. [ABSTRACT FROM AUTHOR]

Reliable, fast and cost efficient mercury analysis is paramount to assess Hg levels in a huge variety of matrices, from soil and water to a variety of foodstuffs. In this work, a novel concept was adopted for seafood and hair analysis, which combines a simplified methylmercury extraction and photochemical vapour generation of Hg0 with liquid chromatography and atomic fluorescence spectrometry (LC-AFS). This concept reduces the number of reagents required to methanol and APDC for extraction and separation of Hg species, and acetic acid, which when combined with UV generates volatile Hg0 in one single step. Here, we compare conventional chemical vapour generation (CVG) with photochemical vapour generation (PVG) for seafood and hair matrix. Our results show that the LC-PVG-AFS method offers lower detection limits and higher precision than that of LC-CVG-AFS measurements by a factor of two. The extraction and LC-PVG-AFS technique was validated using 7 seafood and hair reference materials, yielding methylmercury recoveries of 93.2% to 105%. Further validation was carried out by comparing results from methylmercury determination in 14 tuna samples by the LC-PVG-AFS method to results obtained by GC-AFS, showing R2 = 0.98 and a gradient of 1.0077, which indicates good correlation between the newly developed LC-PVG-AFS technique to an already validated GC-AFS method. [ABSTRACT FROM AUTHOR]