Jiang Hongmei, Hu Bin, Chen Beibei, Xia Linbo
Department of Chemistry, Wuhan University, Wuhan 430072, China.
Anal Chim Acta. 2009 Feb 16;634(1):15-21. doi: 10.1016/j.aca.2008.12.008. Epub 2008 Dec 11.
A new method of hollow fiber liquid phase microextraction (HF-LPME) using ammonium pyrrolidine dithiocarbamate (APDC) as extractant combined with electrothermal atomic absorption spectrometry (ETAAS) using Pd as permanent modifier has been described for the speciation of As(III) and As(V). In a pH range of 3.0-4.0, the complex of As(III)-APDC complex can be extracted using toluene as the extraction solvent leaving As(V) in the aqueous layer. The post extraction organic phase was directly injected into ETAAS for the determination of As(III). To determine total arsenic in the samples, first As(V) was reduced to As(III) by l-cysteine, and then a microextraction method was performed prior to the determination of total arsenic. As(V) assay was based on subtracting As(III) form the total arsenic. All parameters, such as pH of solution, type of organic solvent, the amount of APDC, stirring rate and extraction time, affecting the separation of As(III) from As(V) and the extraction efficiency of As(III) were investigated, and the optimized extraction conditions were established. Under optimized conditions, a detection limit of 0.12ngmL(-1) with enrichment factor of 78 was achieved. The relative standard deviation (R.S.D.) of the method for five replicate determinations of 5ngmL(-1) As(III) was 8%. The developed method was applied to the speciation of As(III) and As(V) in fresh water and human hair extracts, and the recoveries for the spiked samples are 86-109%. In order to validate the developed method, three certified reference materials such as GBW07601 human hair, BW3209 and BW3210 environmental water were analyzed, and the results obtained were in good agreement with the certified values provided.
描述了一种以吡咯烷二硫代氨基甲酸铵（APDC）为萃取剂的中空纤维液相微萃取（HF-LPME）新方法，并将其与以钯为永久改性剂的电热原子吸收光谱法（ETAAS）相结合用于砷（III）和砷（V）的形态分析。在pH值为3.0 - 4.0的范围内，以甲苯为萃取溶剂可萃取砷（III）- APDC络合物，使砷（V）留在水相中。萃取后的有机相直接注入ETAAS中测定砷（III）。为了测定样品中的总砷，先用L-半胱氨酸将砷（V）还原为砷（III），然后在测定总砷之前进行微萃取。砷（V）的测定是基于从总砷中减去砷（III）。研究了溶液pH值、有机溶剂类型、APDC用量、搅拌速率和萃取时间等所有影响砷（III）与砷（V）分离及砷（III）萃取效率的参数，并建立了优化的萃取条件。在优化条件下，实现了0.12 ng mL⁻¹的检出限和78的富集因子。该方法对5 ng mL⁻¹砷（III）进行五次重复测定的相对标准偏差（R.S.D.）为8%。所开发的方法应用于淡水和人发提取物中砷（III）和砷（V）的形态分析，加标样品的回收率为86 - 109%。为了验证所开发的方法，分析了三种有证标准物质，如GBW07601人发、BW3209和BW3210环境水，所得结果与提供的认定值吻合良好。
