Yin Xue-Bo, Yan Xiu-Ping, Jiang Yan, He Xi-Wen
Central Laboratory, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin, China.
Anal Chem. 2002 Aug 1;74(15):3720-5. doi: 10.1021/ac025735w.
A novel hyphenated technique, on-line coupling of capillary electrophoresis (CE) to atomic fluorescence spectrometry (AFS), was developed for speciation analysis of four environmentally significant and toxic forms of arsenic: arsenite, arsenate, monomethylarsenic acid, and dimethylarsenic acid. Baseline separation of the four arsenic species was achieved by capillary electrophoresis in a 50 cm x 100 microm i.d. fused-silica capillary at 20 kV and using a 20 mmol L(-1) phosphate buffer (pH 6.5). A hydride generation (HG) technique was employed to convert the arsenic species from the CE effluent into their respective hydrides. The CE-AFS interface was constructed on the basis of a cross design for introducing a sheath flow around the CE capillary and a Pt electrode, which provided an electrical connection for stable electrophoretic separations and allowed on-line volatile hydride formation. A laboratory-made gas-liquid separator was used to isolate the generated volatile species from the reaction mixture solution, and an argon flow was used to transport the volatile hydrides into the atomizer of AFS for on-line detection. The precision (RSD, n = 7) ranged from 2.1 to 3.1% for migration time, from 2.8 to 4.2% for peak area response, and from 2.0 to 4.1% for peak height response for the arsenic species at the 1 mg L(-1) (as As) level. The detection limits were in the range of 9-18 microg L(-1) (as As). The recoveries of the four arsenic species in locally collected water samples and urine sample ranged from 91 to 115%. The developed technique was successfully applied to the speciation of the water-methanol extractable arsenic in a sediment sample.
一种新型联用技术——毛细管电泳（CE）与原子荧光光谱法（AFS）在线联用，被开发用于对四种具有环境意义且有毒的砷形态进行形态分析：亚砷酸盐、砷酸盐、一甲基砷酸和二甲基砷酸。通过在一根50 cm×100 μm内径的熔融石英毛细管中，于20 kV电压下使用20 mmol L⁻¹磷酸盐缓冲液（pH 6.5）进行毛细管电泳，实现了这四种砷形态的基线分离。采用氢化物发生（HG）技术将CE流出物中的砷形态转化为各自的氢化物。CE - AFS接口基于一种交叉设计构建，用于在CE毛细管和铂电极周围引入鞘流，该鞘流为稳定的电泳分离提供电连接，并允许在线形成挥发性氢化物。使用自制的气液分离器从反应混合溶液中分离出生成的挥发性物质，并使用氩气流将挥发性氢化物输送到AFS的原子化器中进行在线检测。对于1 mg L⁻¹（以As计）水平的砷形态，迁移时间的精密度（RSD，n = 7）范围为2.1%至3.1%，峰面积响应为2.8%至4.2%，峰高响应为2.0%至4.1%。检测限在9 - 18 μg L⁻¹（以As计）范围内。本地采集的水样和尿样中四种砷形态的回收率在91%至115%之间。所开发技术成功应用于沉积物样品中水 - 甲醇可萃取砷的形态分析。
