海藻样品中无机砷测定方法的研究.doc

海藻样品中无机砷测定方法的研究 韦昌金, 刘霁欣*, 徐浩 北京吉天仪器有限公司 北京 100016 摘要 通过比较总砷提取率、加标回收率和砷形态的转化，考察了提取剂组成、样品与提取剂比例、无机砷的检测方法，建立了一种新的海藻中无机砷含量的测量方法：1.2 mol/L HCl提取后再用双氧水氧化，之后采用等度高效液相色谱-氢化物发生原子荧光(HPLC-HGAFS)方法测量，该方法对无机砷的最小检出浓度为0.06mg/kg。采用此方法测定了多种海藻样品中无机砷含量，发现除羊栖菜无机砷含量达到了37.1mg/kg外，其它海藻中无机砷含量均低于0.2mg/kg。另外，采用该方法对海藻样品中总砷的提取率都达到了80.0%以上，绝大部分可达85.0%以上；各种样品的加标回收率都在75.0~110.0%的范围之内。 关键词 形态分析，海藻，无机砷，前处理方法 中图分类号 Investigation of determination method for inorganic arsenic in seaweeds Changjin Wei，Jixin Liu*， (Beijing Titan Instruments Co., Ltd, 100016, Beijing, China) Abstract Extraction reagents, ratio of the sample to extraction reagent, separation methods were optimized to develop a new determination methodology of inorganic arsenic in seaweeds, By comparing extraction efficiency, spiked recovery and the transformation of arsenic species, This method included: the seaweeds were extracted with 1.2 mol/L HCl, then the extracts were subsequently oxidized with peroxide, finally As(V) in oxidized extracts were determined with isocratic high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) to quantify inorganic arsenic. The determined minimal inorganic arsenic of the methodology (2 times of the noise) was 0.06mg/kg. Applying the new methodology to analyze the inorganic arsenic in seaweeds, the results indicated that inorganic arsenic in a majority of seaweeds were less than 0.2 mg/kg, except hijiki in which inorganic arsenic was up to 37.1 mg/kg. By this method, the extraction efficiencies were more than 80.0 % and the spiked recoveries from 75.0 to 110.0% were obtained. Keywords Speciation analysis, seaweeds, inorganic arsenic, extraction method 1. 前言 自然界中，砷的主要形态有：砷酸盐(As(V))、亚砷酸盐(As(III))、一甲基砷化合物(MMA)、二甲基砷化合物(DMA)、三甲基砷的氧化物(TMAO)、砷甜菜碱(AsB)、砷胆碱(AsC)和砷糖(AsS)等，其中的无机砷(iAs，包括As(V)、As(III))的毒性很高，而有机砷中仅有MMA和DMA有较小的毒性，其它有机形态大多无毒，所以可简单的认为无机砷的含量基本能够反映样品中有毒砷的含量。据文献报道[1, 2]，多数海藻中基本不含无机砷，其主要砷形态是大量的AsS和少量DMA，但这两种砷形态都有一定的氢化物发生能力[3]，会对目前国内测定无机砷常用的氢化物原子荧光光度法[4