Ndung'u Kuria, Hibdon Sharon, Flegal A Russell
Environmental Toxicology, WIGS University of California, Santa Cruz, CA 95064, USA; Institute of Applied Environmental Research (ITM), Stockholm University, Frescativagen 54, S-106 91 Stockholm, Sweden.
Talanta. 2004 Sep 8;64(1):258-63. doi: 10.1016/j.talanta.2004.02.017.
Lead concentrations of 59 different types of vinegars (15-307mugl(-1) in balsamic vinegars and 36-50mugl(-1) in wine vinegars) were determined using both inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). Although the precision of direct analyses, following simple aqueous dilutions, with either instrumental method was poor; that precision, following nitric acid and/or hydrogen peroxide digestions, markedly improved with either instrument and the values obtained with the two instruments were in good agreement. The efficacy of different digestions, including (1) nitric acid using a heating block, with or without addition of hydrogen peroxide and (2) mixtures of nitric acid and hydrogen peroxide using ultraviolet (UV) photolysis, were then assessed. The latter procedure was found to be much faster and more efficient, but it was limited by the relatively high levels of contaminant lead in hydrogen peroxide. Consequently, it is recommended that lead concentrations in vinegar be measured following a nitric acid digestion and UV photolysis to oxidize all organic matter before ICP-MS or GFAAS analysis; and it is further recommend that the thermal settings for the latter analyses be adjusted to account for the apparent presence of relatively volatile organolead compounds in vinegar digests.
使用电感耦合等离子体质谱法（ICP-MS）和石墨炉原子吸收光谱法（GFAAS）测定了59种不同类型醋中的铅浓度（香醋中为15 - 307μg l⁻¹，葡萄酒醋中为36 - 50μg l⁻¹）。尽管在简单水稀释后直接用这两种仪器方法进行分析的精密度较差，但在硝酸和/或过氧化氢消解后，两种仪器的精密度都显著提高，且两种仪器获得的值吻合良好。然后评估了不同消解方法的效果，包括（1）使用加热块的硝酸消解，添加或不添加过氧化氢，以及（2）使用紫外线（UV）光解的硝酸和过氧化氢混合物消解。发现后一种方法更快且更有效，但受到过氧化氢中相对较高水平的铅污染物的限制。因此，建议在进行ICP-MS或GFAAS分析之前，先通过硝酸消解和UV光解氧化所有有机物后再测量醋中的铅浓度；还建议调整后一种分析的热设置，以考虑醋消解物中相对挥发性有机铅化合物的明显存在。
