Evaluation of different sample pre-treatment and extraction procedures for mercury speciation in fish samples

Abstract

Investigations are described to select the most suitable drying and extraction procedures for mercury speciation in fish samples. The criteria for selection were good recovery and preservation of the original species information. Three different drying techniques were evaluated: oven-dried, microwave oven-dried and freezedried. Best results were obtained when oven-dried, but microwave dried or freeze-dried showed mercury losses. The four extraction methods investigated were: HCl leaching, alkaline-methanol extraction with tetramethylammonium hydroxide (TMAH) and with KOH, and sodium dodecyl sulfate (SDS) extraction. The extraction efficiency was determined by comparing the total amount of mercury in the samples after microwave digestion with the amount extracted by the different methods described. Mercury measurements were carried out by flow injection-cold vapour-atomic fluorescence spectrometry (FI-CV-AFS). Quantitative mercury extraction was only achieved with HCl leaching (97%). Species integrity after extraction was evaluated by investigating the extracts with capillary gas chromatography-atomic fluorescence spectrometry. Artificial formation of dimethylmercury occurs when TMAH is used as extractant. HCl leaching-GC-AFS was finally applied to methylmercury determination in tuna fish and swordfish samples, and gave results in the range 0.78-1.93 mg kg 21 . The detection limit for monomethylmercury (MMHg) was found to be 1.2 pg.

Energy stores and mercury concentrations in a common minnow (spottail shiner, Notropis hudsonius) associated with a peaking hydroelectric dam

“…Homogenate aliquots were desiccated in a drying oven at 50°C in order to maximize Hg recovery, and total Hg was measured in lieu of MeHg (Bloom, 1992; Cabañero Ortiz, Albarrán, & Rica, 2002; Greenfield & Jahn, 2010; Jackson, 1991). Samples were homogenized in acid‐washed scintillation vials with glass rods and analyzed on a Direct Mercury Analyzer using dogfish muscle (DORM‐4) as a certified reference material (CRM; DMA 80, Milestone, Shelton, CT; National Research Council, Ottawa, Ontario, Canada).…”

Double Spike Isotope Dilution GC-ICP-MS for Evaluation of Mercury Species Transformation in Real Fish Samples Using Ultrasound-Assisted Extraction

“…A significant piece of fresh fish muscle was homogenized with a metal-free mixer. A part of this sample was oven-dried at 40 °C for 24 h up to constant weight and finally converted into powder by agate mortar grinding. The other part of the fresh sample was extracted directly after homogenization.…”

High‐Throughput Mercury Monitoring in Indoor Dust Microsamples by Bath Ultrasonic Extraction and Anodic Stripping Voltammetry on Gold Nanoparticles‐Modified Screen‐Printed Electrodes

“…As compiled by Gao et al 14 in a current review, a number of pretreatments are described in the literature for total mercury and mercury speciation analysis in environmental and biological samples. Pretreatment methodologies are generally based on microwave assisted acid leaching or alkaline dissolution methods 15, 16, enzymatic hydrolysis 17 and ultrasonic extraction in a bath 13, 18–20, with a probe 21, 22 or combinations of them 1. Also, some recent applications about simple slurry preparation for Hg determination are reported 9, 23, 24.…”