Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Talanta. 2010 Apr 15;81(1-2):213-21. doi: 10.1016/j.talanta.2009.11.060. Epub 2009 Dec 3.
Arsenic (As) speciation in muscle tissues of freshwater fish was investigated with special emphasis on extraction yields and mass balances. For the quantification of water-soluble As compounds, samples were extracted using a 1:1 (v/v) methanol/water mixture. Various extraction parameters, such as extraction volume, number of additional extractions, intermediate and final volume in sample preconcentration were optimized so as to improve the extraction efficiency. Arsenic compounds were determined by HPLC with online ICP-MS, using both cation and anion exchange separation. The species studied were eel (Anguilla anguilla L.), flathead grey mullet (Mugil cephalus L.), chub (Leuciscus cephalus L.), and carp (Cyprinus carpio L.). Mean total As concentrations ranged from 354 microg kg(-1) dry weight (carp) to 1804 microg kg(-1) dry weight (mullet). Under optimized conditions, the percentage of total As extracted ranged from 64% for carp, to 82%, 84%, and 89% for grey mullet, eel and chub, respectively. Extraction of lipid-rich eel with n-hexane recovered some additional 3% of total As. The sizeable effect of sample matrix on HPLC retention time of some organoarsenicals in gradient elution cation exchange chromatography was exploited to achieve separation of coeluting compounds by analysing the same sample at different dilutions. The recovery of As from chromatographic columns was 101%, 102%, 103% and 104% for carp, chub, mullet and eel, respectively, indicating that no As was retained during chromatography. Arsenobetaine (AB) was the dominating As compound, but several other arsenicals, including arsenous acid (Asiii), arsenic acid (Asv), methylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), arsenocholine ion (AC), tetramethylarsonium ion (TETRA), oxo-arsenosugar-glycerol (AS1), oxo-arsenosugar-phosphate (AS2), oxo-arsenosugar-sulfate (AS4), thio-arsenosugar-phosphate (ThioAS2), and three unknown As compounds, were found. Arsenic speciation in carp was different compared to the other fish species, and a lower proportion of AB along with a high contribution of AS2 and ThioAS2 was found. DMA and TMAO were noteworthy minor compounds in eel and carp, respectively. Arsenic speciation and the chemical composition of fish muscle both appeared to affect the extraction yield.
研究了淡水鱼肌肉组织中的砷形态，特别强调了提取率和质量平衡。为了定量测定水溶性砷化合物，采用 1:1（v/v）甲醇/水混合物提取样品。优化了各种提取参数，如提取体积、额外提取次数、样品预浓缩过程中的中间和最终体积，以提高提取效率。采用高效液相色谱-电感耦合等离子体质谱法（HPLC-ICP-MS），同时使用阳离子和阴离子交换分离，对砷化合物进行了测定。研究的物种为鳗鱼（Anguilla anguilla L.）、平鲷（Mugil cephalus L.）、鲫鱼（Leuciscus cephalus L.）和鲤鱼（Cyprinus carpio L.）。总砷浓度的平均值范围为 354μgkg(-1)干重（鲤鱼）至 1804μgkg(-1)干重（平鲷）。在优化条件下，鲤鱼总砷的提取率为 64%，而平鲷、鳗鱼和鲫鱼的提取率分别为 82%、84%和 89%。用正己烷提取富含脂质的鳗鱼可回收约 3%的总砷。在梯度洗脱阳离子交换色谱中，利用样品基质对某些有机砷化合物在高效液相色谱保留时间的显著影响，通过在不同稀释度下分析同一样品，实现了共洗脱化合物的分离。从色谱柱中回收的砷对鲤鱼、鲫鱼、平鲷和鳗鱼的回收率分别为 101%、102%、103%和 104%，表明在色谱过程中没有砷被保留。砷甜菜碱（AB）是主要的砷化合物，但还发现了其他几种砷化合物，包括亚砷酸（Asiii）、砷酸（Asv）、甲基砷酸（MMA）、二甲基砷酸（DMA）、三甲基砷氧化物（TMAO）、砷胆碱离子（AC）、四甲基砷离子（TETRA）、氧代-砷糖-甘油（AS1）、氧代-砷糖-磷酸盐（AS2）、氧代-砷糖-硫酸盐（AS4）、硫代-砷糖-磷酸盐（ThioAS2）和三种未知的砷化合物。鲤鱼中的砷形态与其他鱼类不同，发现 AB 的比例较低，而 AS2 和 ThioAS2 的贡献较高。DMA 和 TMAO 分别是鳗鱼和鲤鱼中的重要微量化合物。砷形态和鱼类肌肉的化学成分似乎都影响了提取率。
