电感耦合等离子体质谱法分析海蟹中的砷元素分布特征

分别采用电感耦合等离子体质谱（inductively coupled plasma mass spectrometry，ICP-MS）法和高效液相色谱-ICP-MS测定4 种海蟹（青蟹、三疣梭子蟹、日本鲟和细点圆趾蟹）及其不同部位（胸肌肉、钳肉、肝胰腺、性腺（雌）和鳃）中总砷及砷形态分布特征。样品加酸、微波消解后采用ICP-MS法测定总砷；样品经稀硝酸溶液提取、正已烷脱脂净化后，采用Dionex IonPac AS19保护柱（50 mm×4 mm）及AS19阴离子交换柱（250 mm×4 mm，10 μm）作为分析柱、pH 9.5的50 mmol/L碳酸铵溶液作为流动相等度洗脱的液相分离条件和优化后的ICP-MS条件，测定砷甜菜碱（arsenobetaine，AsB）、一甲基砷、二甲基砷、三价砷（As（III））、五价砷（As（V））5 种砷形态含量。经方法优化后，5 种砷化合物的标准溶液在0～300 μg/L质量浓度范围内，呈现良好的线性关系（r2＞0.998），检出限为0.008～0.014 mg/kg，定量限为0.025～0.055 mg/kg；在样品中添加0.4、1.0 mg/kg和2.0 mg/kg的水平下，加标回收率为70.0%～105.0%，相对标准偏差低于5%；158 个海蟹类样品中总砷含量范围为0.37～35.81 mg/kg，整蟹及分部位的砷形态物测定数据表明海蟹体内均以毒性较低的AsB为主，AsB占其总砷含量的60.9%～99.4%，无机砷含量均值在0～0.12 mg/kg之间，无机砷含量均未超过国家标准限量值；总砷和AsB的含量基本都呈现出细点圆趾蟹＜青蟹＜三疣梭子蟹＜日本鲟、同一品种下性腺（雌）＞肝胰腺＞蟹胸肌肉＞蟹钳肉＞蟹鳃的变化趋势，说明海蟹富集砷能力较强，性腺和肝胰腺是其砷富集的主要器官。

Species Analysis and Distribution Characteristics of Arsenic in Sea Crabs by Inductively Coupled Plasma Mass Spectrometry

The distribution characteristics of total arsenic and arsenic species in four sea crabs (Scylla serrata, Portunus trituberculatus, Charybdis japonica and Ovalipes punctatus) and their different tissues (chest muscle, clamp meat, hepatopancreas and female gonad and gill) were studied by inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Samples were acidified, digested in microwave and tested by ICP-MS for total arsenic. After samples were extracted with dilute nitric acid solution and degreased with n-hexane, an HPLC-ICP-MS method using a Dionex IonPac AS19 guard column (50 mm × 4 mm) and an AS19 anion exchange analytical column (250 mm × 4 mm, 10 μm) with 50 mmol/L carbon acid ammonium (pH 9.5) in isocratic elution as the mobile phase was used to analyze 5 arsenic species (AsB, MMA, DMA, As (III), and As (V)). The optimized method showed a good linear relationship over the concentration range of 0–300 μg/L (r2 > 0.998). The limits of detection (LOD) and the limits of quantity (LOQ) were 0.008–0.014 mg/kg and 0.025–0.055 mg/kg, respectively. The recovery rates at spiked levels of 0.4–2.0 mg/kg were 70.0%–105.0% with relative standard deviations (RSDs) smaller than 5%. Total arsenic contents in 158 sea crab samples were 0.37–35.81 mg/kg, and the analytical data of arsenic species in whole crabs and crab tissues showed that AsB, with low toxicity, was the main form of arsenic in sea crab, accounting for 60.9%–99.4% of the total arsenic. Additionally, average inorganic arsenic content was only 0–0.12 mg/kg in all samples, below the national standard limit. The contents of total arsenic and AsB in different sea crab species were in the ascending order of O. punctatus < S. serrata < P. trituberculatus < C. japonica, and those in different crab tissues were in the descending order of female gonad > hepatopancreas > chest muscle > clamp meat > gill. This research suggested that sea crabs have strong As accumulation ability, mainly in gonad and hepatopancreas.