Shemirani Farzaneh, Baghdadi Majid, Ramezani Majid
Department of Chemistry, Faculty of Science, University of Tehran, Tehran, Iran.
Talanta. 2005 Feb 28;65(4):882-7. doi: 10.1016/j.talanta.2004.08.009.
A new approach for developing a cloud point extraction-electrothermal atomic absorption spectrometry has been described and used for determination of arsenic. The method is based on phase separation phenomenon of non-ionic surfactants in aqueous solutions. After reaction of As(V) with molybdate towards a yellow heteropoly acid complex in sulfuric acid medium and increasing the temperature to 55 degrees C, analytes are quantitatively extracted to the non-ionic surfactant-rich phase (Triton X-114) after centrifugation. To decrease the viscosity of the extract and to allow its pipetting by the autosampler, 100mul methanol was added to the surfactant-rich phase. An amount of 20mul of this solution plus 10mul of 0.1% m/v Pd(NO(3))(2) were injected into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. Total inorganic arsenic(III, V) was extracted similarly after oxidation of As(III) to As(V) with KMnO(4). As(III) was calculated by difference. After optimization of the extraction condition and the instrumental parameters, a detection limit (3sigma(B)) of 0.01mugl(-1) with enrichment factor of 52.5 was achieved for only 10ml of sample. The analytical curve was linear in the concentration range of 0.02-0.35mugl(-1). Relative standard deviations were lower than 5%. The method was successfully applied to the determination of As(III) and As(V) in tap water and total arsenic in biological samples (hair and nail).
本文描述了一种用于开发浊点萃取-电热原子吸收光谱法的新方法，并将其用于测定砷。该方法基于非离子表面活性剂在水溶液中的相分离现象。在硫酸介质中，砷（V）与钼酸盐反应生成黄色杂多酸络合物，然后将温度升至55℃，离心后，分析物被定量萃取到富含非离子表面活性剂的相中（Triton X-114）。为了降低萃取液的粘度并使其能够通过自动进样器移取，向富含表面活性剂的相中加入100μl甲醇。取20μl该溶液加10μl 0.1% m/v Pd(NO₃)₂注入石墨管，用电热原子吸收光谱法测定分析物。用高锰酸钾将砷（III）氧化为砷（V）后，同样地萃取总无机砷（III、V）。砷（III）通过差值计算得出。在优化萃取条件和仪器参数后，仅对10ml样品就实现了0.01μg l⁻¹的检出限（三倍空白标准偏差）和52.5的富集因子。分析曲线在0.02 - 0.35μg l⁻¹浓度范围内呈线性。相对标准偏差低于5%。该方法成功应用于自来水中砷（III）和砷（V）以及生物样品（头发和指甲）中总砷的测定。
