Rattanachongkiat S, Millward G E, Foulkes M E
School of Earth, Ocean and Environmental Sciences, University of Plymouth, Plymouth, PL4 8AA, UK.
J Environ Monit. 2004 Apr;6(4):254-61. doi: 10.1039/b312956j. Epub 2004 Mar 19.
Suitable techniques have been developed for the extraction of arsenic species in a variety of biological and environmental samples from the Pak Pa-Nang Estuary and catchment, located in Southern Thailand, and for their determination using HPLC directly coupled with ICP-MS. The estuary catchment comprises a tin mining area and inhabitants of the region can suffer from various stages of arsenic poisoning. The important arsenic species, AsB, DMA, MMA, and inorganic arsenic (As III and V) have been determined in fish and crustacean samples to provide toxicological information on those fauna which contribute to the local diet. A Hamilton PRP-X100 anion-exchange HPLC system employing a step elution has been used successfully to achieve separation of the arsenic species. A nitric acid microwave digestion procedure, followed by carrier gas nitrogen addition- (N2)-ICP-MS analysis was used to measure total arsenic in sample digests and extracts. The arsenic speciation of the biological samples was preserved using a Trypsin enzymatic extraction procedure. Extraction efficiencies were high, with values of 82-102%(As) for fish and crustacean samples. Validation for these procedures was carried out using certified reference materials. Fish and crustacean samples from the Pak Pa-Nang Estuary showed a range for total arsenic concentration, up to 17 microg g(-1) dry mass. The major species of arsenic in all fauna samples taken was AsB, together with smaller quantities of DMA and, more importantly, inorganic As. For sediment samples, arsenic species were determined following phosphoric acid (1 M H3PO4) extraction in an open focused microwave system. A phosphate-based eluant, pH 6-7.5, with anion exchange HPLC coupled with ICP-MS was used for separation and detection of AsIII, AsV, MMA and DMA. The optimum conditions, identified using an estuarine sediment reference material (LGC), were achieved using 45 W power and a 20 minute heating period for extraction of 0.5 g sediment. The stability and recovery of arsenic species under the extraction conditions were also determined by a spiking procedure which included the estuarine sediment reference material. The results show good stability for all species after extraction with a variability of less than 10%. Total concentrations of arsenic in the sediments from the Pak Pa-Nang river catchment and the estuary covered the ranges 7-269 microg g(-1)and 4-20 [micro sign]g g(-1)(dry weight), respectively. AsV was the major species found in all the sediment samples with smaller quantities of AsIII. The presence of the more toxic inorganic forms of arsenic in both sediments and biota samples has implications for human health, particularly as they are readily 'available'.
已开发出合适的技术，用于从泰国南部的帕巴农河口和集水区的各种生物和环境样品中提取砷形态，并使用直接与电感耦合等离子体质谱仪（ICP-MS）联用的高效液相色谱法（HPLC）对其进行测定。该河口集水区包括一个锡矿区，该地区的居民可能会遭受不同阶段的砷中毒。已对鱼类和甲壳类动物样品中的重要砷形态，如砷甜菜碱（AsB）、二甲基砷酸（DMA）、一甲基砷酸（MMA）和无机砷（As III和As V）进行了测定，以提供有关那些构成当地饮食的动物群的毒理学信息。采用梯度洗脱的汉密尔顿PRP-X100阴离子交换HPLC系统已成功用于实现砷形态的分离。采用硝酸微波消解程序，随后进行载气氮气添加（N2）-ICP-MS分析，以测量样品消解液和提取物中的总砷。使用胰蛋白酶酶促提取程序来保存生物样品的砷形态。提取效率很高，鱼类和甲壳类动物样品的提取效率值为82 - 102%（As）。使用有证标准物质对这些程序进行了验证。帕巴农河口的鱼类和甲壳类动物样品的总砷浓度范围高达17 μg g(-1)干重。所采集的所有动物群样品中的主要砷形态是AsB，还有少量的DMA，更重要的是还有无机砷。对于沉积物样品，在开放式聚焦微波系统中用磷酸（1 M H3PO4）提取后测定砷形态。使用pH 6 - 7.5的基于磷酸盐的洗脱液，结合阴离子交换HPLC与ICP-MS用于AsIII、AsV、MMA和DMA的分离和检测。使用河口沉积物标准物质（LGC）确定的最佳条件是，使用45 W功率和20分钟加热时间来提取0.5 g沉积物。还通过包括河口沉积物标准物质的加标程序确定了提取条件下砷形态的稳定性和回收率。结果表明，提取后所有形态的稳定性良好，变异系数小于10%。帕巴农河流域和河口沉积物中的总砷浓度范围分别为7 - 269 μg g(-1)和4 - 20 μg g(-1)（干重）。AsV是所有沉积物样品中发现的主要形态，还有少量的AsIII。沉积物和生物群样品中存在毒性更强的无机砷形态对人类健康有影响，特别是因为它们很容易“被利用”。
