水中砷(Ⅲ)和砷(Ⅴ)的N-甲基咪唑阴离子交换树脂分离-X射线荧光光谱测定法

Separation and determination of arsenic(Ⅲ) and arsenic(Ⅴ) in water by N-methylimidazolium anion exchange resin and X-ray fluorescence spectrometry

目的建立水中As（Ⅲ）和As（Ⅴ）的N-甲基咪唑阴离子交换树脂分离-X射线荧光光谱测定法。方法合成了N-甲基咪唑固载化阴离子交换树脂并优化了其对As（Ⅴ）选择性吸附条件,实现了As（Ⅲ）和As（Ⅴ）的分离。利用波长色散X射线荧光光谱法,采用氦气保护下液体直接进样,分别测定As（Ⅲ）和As（Ⅴ）的浓度。结果当p H为9时,室温振荡2 h,As（Ⅲ）和As（Ⅴ）在氯型N-甲基咪唑官能团化的强碱阴离子交换树脂（RCl）表面的吸附率分别达到2.3%和99.4%,能够满足分离要求。在2.05-200 mg/L浓度范围内的线性关系良好,r=0.999 8。该方法的检出限为0.3 mg/L,回收率为96.3%-105.0%,RSD〈2.00%。树脂还能通过离子交换再生而重复使用。结论方法具有快速、灵敏、准确、环保的特点,适用于水中砷的测定。

Objective To establish a method for the determination of trace arsenic（Ⅲ） and arsenic（Ⅴ） in water by N-methylimidazolium anion exchange resin and X-ray fluorescence spectrometry. Methods N-methylimidazolium functionalized anion exchange resin was prepared and the conditions of its selective absorption of As（Ⅴ） was optimized to fulfill the separation of As（Ⅲ） and As（Ⅴ）. The water samples can be handled directly with helium shielding gas atmosphere, and the amounts of the trace As（Ⅲ） and As（Ⅴ） were measured by wave-dispersive X-ray fluorescence spectrometry. Results At p H 9, the adsorption efficiencies of As（Ⅲ） and As（Ⅴ） on the surface of N-methylimidazolium-funtionalized strongly basic anion exchange resin with Cl-form（RCl） could reach to 2.3% and 99.4% respectively in 2 h shaking at room temperature, which fulfilled the separation request. Good linearity was shown when the concentrations of arsenic ranged from 2.05 mg/L to 200 mg/L,the correlation coefficient was 0.999 8. The limit of detection was 0.3 mg/L and the recovery of standard addition were 96.3%-105.0%. RSDs were less than 2.00 %. The resin was able to be regenerated after ion exchange. Conclusion The method is rapid, sensitive,accurate and eco-friendly,and is helpful to evaluate water toxicity, suitable for long-term and frequent investigation of vast water samples.