Analytical speciation of mercury in fish tissues by reversed phase liquid chromatography-inductively coupled plasma mass spectrometry with Bi3 as internal standard

作者：Maldonado Santoyo Maria; Landero Figueroa Julio Alberto; Wrobel Kazimierz; Wrobel Katarzyna

来源：Talanta, 2009, 79(3): 706-711.

DOI：10.1016/j.talanta.2009.04.057

• Mercury speciation
• Extraction
• Internal standard
• HPLC-ICP-MS

In this work, the quantification of two mercury species (Hg2+ and CH3Hg+) in fish tissues has been revisited. The originality of our approach relies on the use of Bi3+ as internal standard (IS) and on the modification of typical extraction conditions. The IS (125 mu l, 1000 mu g l(-1) Bi3+) was added to the aliquot of fresh fish tissue (400-500 mg). A high-speed blender and ultrasound-assisted homogenization/extraction was carried out in the presence of perchloric acid (1.5 ml, 0.6 mol l(-1)), L-CySteine (500 mu l, 0.75 mol l(-1)) and 500 mu l toluene: methanol (1:1). Perchloric acid was used for protein denaturation and precipitation. toluene helped to destroy lipid structures potentially sequestering (CHHg+)-Hg-3. L-CySteine was used to form water-soluble complexes with Bi3+, Hg2+ and CH3Hg+. The excess of perchloric acid was eliminated by addition of potassium hydroxide (pH 5 with acetic acid). The obtained extract, was diluted with the mobile phase (1:1) and introduced (20 mu l) to the reversed phase HPLC-ICP-MS system. The separation was achieved by isocratic elution(2.5 mmol l(-1) cysteine, 12.5 mmol l(-1) (NH4)(2)HPO4, 0.05% triethylamine, pH 7.0:methanol (96:4)) at a flow rate 0.6 ml min(-1). Column effluent was on-line introduced to ICP-MS for specific detection of Hg-202, Hg-200 and Bi-209. Analytical signal was defined as the ratio between Hg-202/Bi-209 peak areas. The detection limits evaluated for Hg2+ and CH3Hg+ were 0.8 and 0.7 mu g l(-1). Recovery of the procedure, calculated as the sum of species concentrations found in the sample with respect to total ICP-MS-determined Hg was 91.9% for king mackerel muscle and 89.5% for red snapper liver. In the standard addition experiments, the recovery results were 98.9% for Hg2+ and 100.6% for CH3Hg+. It should be stressed that the use of Bi3+ as IS enabled to improve analytical performance by compensating for incomplete extraction and for imprecision of sample handling during relatively non-rigorous protocol.

• 出版日期2009-8-15