Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
J Mass Spectrom. 2010 Feb;45(2):205-14. doi: 10.1002/jms.1705.
In this work, dual-column capillary microextraction (CME) system consisting of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS)-silica coated capillary (C1) and 3-mercaptopropyl trimethoxysilane (MPTS)-silica coated capillary (C2) was developed for sequential separation/preconcentration of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] in the extracts of human hair followed by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) detection with iridium as permanent modifier. Various experimental parameters affecting the dual-column microextraction of different As species had been investigated in detail. It was found that at pH 9, As(V) and MMA could be quantitatively retained by C1 and only As(III) could be quantitatively retained by C2. With the aid of valve switching, As(V)/MMA(V) retained on C1 and As(III) retained on C2 could be sequentially desorbed by 10 microl of 0.01 mol l(-1) HNO(3) [for As(V)], 0.1 mol l(-1) HNO(3) [for MMA(V)] and 0.2 mol l(-1) HNO(3)-3% thiourea (m/v) [for As(III)], respectively, the eluents were immediately introduced into the Ir-coated graphite tubes for further ETV-ICP-MS detection. With two-step ETV pyrolysis program, Cl(-) in the sample matrix could be in situ removed, and the total As in the human hair extracts or digested solution could be interference-free, determined by ETV-ICP-MS. DMA(V) in the human hair extracts was obtained by subtraction of total As in the human hair extracts from other three As species. Under the optimized conditions, the detection limits (3 sigma) of the method were 3.9 pg ml(-1) for As(III), 2.7 pg ml(-1) for As(V), 2.6 pg ml(-1) for MMA(V) and 124 pg ml(-1) for total As with the relative standard deviations less than 7.0% (C = 0.1 ng ml(-1), n = 7), and the enrichment factor was 286, 262 and 260 for As(III), As(V) and MMA(V), respectively. The developed method was successfully applied for the speciation of arsenic in the extracts of human hair.
在这项工作中，开发了一种由 N-(2-氨乙基)-3-氨丙基三甲氧基硅烷 (AAPTS)-涂覆硅胶的毛细管 (C1) 和 3-巯丙基三甲氧基硅烷 (MPTS)-涂覆硅胶的毛细管 (C2) 组成的双柱毛细管微萃取 (CME) 系统，用于顺序分离/预浓缩人发提取物中的亚砷酸盐 [As(III)]、砷酸盐 [As(V)]、一甲基砷酸 [MMA(V)] 和二甲基砷酸 [DMA(V)]，然后用电感耦合等离子体质谱 (ICP-MS) 检测，以铱作为永久修饰剂。详细研究了影响不同砷形态双柱微萃取的各种实验参数。结果表明，在 pH 9 时，C1 可定量保留 As(V)和 MMA，而 C2 可定量保留 As(III)。借助阀切换，C1 上保留的 As(V)/MMA(V)和 C2 上保留的 As(III)可分别用 10 μl 0.01 mol l(-1) HNO(3) [用于 As(V)]、0.1 mol l(-1) HNO(3) [用于 MMA(V)]和 0.2 mol l(-1) HNO(3)-3%硫脲 (m/v) [用于 As(III)]依次洗脱，洗脱液立即引入涂铱石墨管进行进一步的 ETV-ICP-MS 检测。采用两步 ETV 热解程序，可原位去除样品基质中的 Cl(-)，无干扰地测定人发提取物或消化液中的总砷，由 ETV-ICP-MS 测定。人发提取物中的 DMA(V)通过从人发提取物中的总砷中减去其他三种砷形态来获得。在优化条件下，该方法对 As(III)、As(V)、MMA(V)和总砷的检测限 (3σ) 分别为 3.9 pg ml(-1)、2.7 pg ml(-1)、2.6 pg ml(-1)和 124 pg ml(-1)，相对标准偏差小于 7.0% (C = 0.1 ng ml(-1)，n = 7)，富集因子分别为 286、262 和 260。该方法成功应用于人发提取物中砷的形态分析。
