Total Reflection X-Ray Fluorescence Analysis of Toxic Metals in Fish Tissues

Abstract

The concentration of Cr, Ni, Cu, Zn, Hg and Pb, considered like toxic, was evaluated in fish tissues by means the total reflection X-Ray Fluorescence technique (TXRF). Grass carp (Ctenopharygodon idella) samples were collected from six regions of the Tepuxtepec Dam which was used as a water reservoir and fish production for the local population. Fish tissues: gills, liver, kidney and muscle were analyzed in triplicate using a TXRF spectrometer “TX-2000 Ital Structures” with a Si(Li) detector and a resolution of 140 eV (FWHM) at Mn Kα and Mo tube (40 kV, 30 mA) with 17.4 KeV excitation energy. The mean concentration of metals in tissues decrease in the sequence: Kidney ≈ Gills > Liver > Muscle; the range of concentration for Zn was 26.68 - 816.67 mg/Kg followed by Cu: 1.18 - 35.81 mg/Kg, Cr: 1.10 - 9.30 mg/Kg, Ni: 0.40 - 3.80 mg/Kg, Pb: <0.02 - 1.92 mg/Kg and Hg: <0.03 - 1.97 mg/Kg. Chromium and mercury concentrations slightly exceed the limits for fish proposed by FAO/WHO and Mexican Legislation for human consumption in the edible parts of fish from each one of the regions of the Tepuxtepec Dam. The results show that metal accumulation in herbivorous carp tissues was higher in regions 1, 2 and 3 than the others, which could be due to the influence of Lerma River, one of the most polluted rivers of Mexico.