On-line pre-reduction of pentavalent arsenicals by thioglycolic acid for speciation analysis by selective hydride generation-cryotrapping-atomic absorption spectrometry.
On-line pre-reduction of pentavalent arsenicals by thioglycolic acid for speciation analysis by selective hydride generation-cryotrapping-atomic absorption spectrometry.
复制标题
DOI：
10.1016/j.sab.2008.04.006
复制
发表时间：
2008-06
期刊：
影响因子：
--
通讯作者：
S. Musil;Tomáš Matoušek
中科院分区：
文献类型：
--
作者：
S. Musil;Tomáš Matoušek
本文介绍了一种改进的基于预还原的选择性氢化物发生区分三价和五价砷的方法，并应用于多原子化器原子吸收光谱法，以最少的样品预处理，对无机、单、双和三甲基砷的氧化态进行了特定形态分析。然后用低温捕集法对砷化氢、甲砷化氢、二甲砷化氢和三甲砷化氢进行了富集和分离。本研究表明，目前用于五价砷离线预还原的2%（m/v）L-半胱氨酸盐酸盐一水合物（L-cys）可以用1%（m/v）巯基乙酸（TGA）替代。在25 °C下用TGA实现五价砷的更快的预还原，具有与L-cys相同的灵敏度。采用分段流动分析法对热重在线预还原装置进行了优化，以抑制预还原盘管中的轴向分散。有或没有在线预还原测量的标准校准表明所有As形式的均匀和相等的灵敏度。在回收率研究中证明了通过单一物质（例如iAs（III））的水标准品进行标准化以定量尿液中所有其他As形式的可能性。iAs（III）的检测限为100 ng l− 1，iAs（V）的检测限为135 ng l− 1，甲基化砷的检测限为30 - 50 ng l− 1。
An improvement of current method of selective hydride generation based on pre-reduction for differentiation of tri- and pentavalent arsenicals is described, applied for the oxidation state specific speciation analysis of inorganic, mono-, di- and trimethylated arsenicals with minimum sample pretreatment using atomic absorption spectrometry with the multiatomizer. The preconcentration and separation of arsine, methylarsine, dimethylarsine and trimethylarsine are then carried out by means of cryotrapping. The presented study shows that 2% (m/v) L-cysteine hydrochloride monohydrate (L-cys) currently used for off-line pre-reduction of pentavalent arsenicals can be substituted with 1% (m/v) thioglycolic acid (TGA). Much faster pre-reduction of pentavalent arsenicals at 25 °C with equal sensitivities as in the case of L-cys has been achieved with TGA. A setup for on-line pre-reduction by TGA has been optimized, with the application of segmented flow analysis for suppression of axial dispersion in the pre-reduction coil. Standard calibrations measured with or without on-line pre-reduction indicate uniform and equal sensitivities for all As forms. The possibility of standardization by water standards of single species (e.g. iAs(III)) for quantification of all other As forms in urine is demonstrated in the recovery study. Limits of detection were 100 ng l−1for iAs(III), 135 ng l−1for iAs(V) and 30 to 50 ng l−1for methylated arsenicals.