Liquid chromatographic – cold vapour atomic fluorescence spectrometric determination of mercury species

Abstract

Solvent extraction, sonication, and microwave-assisted extractions in the presence of extraction agents (thioacetic acid, citric acid, cysteine, 2-mercaptoethanol, HCl + NaCl, etc.) were tested for the isolation of mercury species. A mixture of 6 M HCl and 0.1 M NaCl was selected as the most suitable extraction agent. The extraction efficiency was about 10% higher and the RSD below 3.3% when microwave-assisted extraction was applied instead of sonication. The liquid chromatography-cold vapour atomic fluorescence spectrometry (LC/CV-AFS) method was optimised and used for separation and determination of inorganic mercury cations and alkylated and arylated mercury species. Isocratic elution at a flow rate of 0.15 mL/min (with a mobile phase containing 0.05% 2-mercaptoethanol (pH = 5) and 7% methanol and with a stepwise increase of methanol content up to 100% MeOH in the 15th min) was used for separation of mercury species on a Hypersil BDS C18 RP column. The limits of detection of the LC/CV-AFS system were estimated as 0.2 microg/L (3%) for MeHg+, 0.07 microg/L (5.3%) for inorganic Hg, 0.06 microg/L (3.4%) for PhHg+, and 0.12 microg/L (4.4%) for EtHg with the corresponding RSDs at 5 microg/L (n = 10) given in parentheses. The concentrations (2-10 mg/kg fresh weight) of total mercury and methylmercury (90-99% of the total mercury) in selected fish obtained by HPLC/CV-AFS were in good agreement (absolute deviations 0.05 mg/kg) but more precise (RSDs <5.4% at 5 mg/L, n = 10) than those determined by GC coupled to an electron capture detector. The RSDs (3.1-8.2% and 4.1-9.0%) of the overall analytical procedure for the determination of total mercury (AMA 254) and methylmercury (HPLC/CV-AFS) were determined for intra-day and inter-day assays, respectively.

Determination of total mercury and mercury species in fish and aquatic ecosystems of Moravian rivers

“…Analytical methods. The methods used for the determination of the total mercury and the mercury species are described elsewhere (Houserova et al, 2006a). Here, only a brief summary is mentioned.…”

Robust microwave-assisted extraction protocol for determination of total mercury and methylmercury in fish tissues

“…In general, sample preparation techniques are time consuming, prone to unpredictable analyte losses, contamination and/or species transformation. Extraction protocols with alkaline reagents using either KOH [9] or TMAH [10][11][12] and acid leaching using HCl [13,14] and CH 3 COOH [15,16] have been proposed mainly to release mercury species from biological samples.…”

“…Although analysis of biological tissues is less affected by artifacts and interferences during extraction procedures and quantification compared to that of sediments [7], methods based on alkaline digestion have been shown to occasionally result in overestimation of the CH 3 Hg + concentration in biological samples [17,18] and interference with the analytical procedure due to matrix effects [13,19]. In addition, recent definitive studies of the interconversion of mercury species during sample preparation for biological tissues using tuna fish tissue samples call into question the accuracy of results using previously reported analytical procedures [20].…”

Adsorption of mercury species on river sediments — effects of selected abiotic parameters

“…The detailed method of mercury species determination is described elsewhere [15]. To summarize: 1.5-3.0 g of sediment sample was extracted for 10 min (6 M HCl + 0.1 M NaCl) in a high-pressure microwave digestion unit (Ethos SEL, Milestone, Italy).…”