Effect of l-cysteine on drying and neutron irradiation loss of Hg, Se, As, and Br from fish tissue

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Powdered, thawed composited, and fresh frozen fish tissues were analyzed for Hg, Se, As, and Br. Experiments were designed to measure or estimate upper limits of long-term storage, drying, and instrumental neutron activation analysis (INAA) irradiation-related analyte losses. Tissue was analyzed as received (dried, if necessary, for INAA) and treated with l-cysteine to determine if such treatment reduces analyte loss, especially for Hg. Untreated tissues experienced large (23–49%) volatile Hg losses during irradiation. l-Cysteine treatment followed by freeze drying reduced Hg losses to 0.9–3.5%. Desiccation over Mg(ClO4)2 and oven drying at 40°C of treated tissues were less successful at reducing Hg irradiation loss. Irradiation losses for volatile Se, As, and Br species were smaller, ranging from 0.06–0.4%, <0.01–0.11%, and 0.02–1.0%, respectively. Treated tissue drying losses for Hg, Se, As, and Br ranged from about 3–20%, ≤2–6%, <0.2–6%, and <0.3–3%, respectively, depending on drying method. There was some evidence that, unlike for Hg, l-cysteine treatment enhanced Se drying loss. There was little evidence of element loss during long-term storage at −80°C, except for an 8% loss from Hg in desiccator dried, l-cysteine treated powdered fish protein.