痕量铜的流动注射-固相萃取-光度法测定

Determination of Trace Amounts of Copper Using a Catalytic Kinetic Spectroscopy Coupled with On-line Flow Injection and Solid-phase Extraction

根据在酸性介质中,Cu2+对溴酸钾氧化藏红T的反应具有催化作用,利用自制的二苯卡巴腙功能键合硅胶做固相萃取固定相,联用流动注射样品处理技术,建立了在线选择性固相萃取催化动力学流动注射光度法测定痕量Cu2+的新方法。研究了富集时间、反应管长、富集和洗脱流速、反应介质及洗脱液、试剂浓度、反应温度和共存物质的影响。在最佳实验条件下,对铜测定的线性范围为0.0010～0.60mg/L,检出限为7.9×10-4mg/L。在线分离富集后分析方法的灵敏度提高20多倍,允许干扰物质存在的倍率提高了近10倍。11次重复测定的相对标准偏差小于2.6%。一份样品溶液从分离富集处理到测定,仅需6min和6mL试剂。方法已用于中药和茶叶中痕量铜的测定。

A new flow-injection catalytic kinetic spectroscopy was developed for the determination of Cu^2＋ based on its catalytic activity on the oxidation of safranine T by potassium bromate in sulfuric acid solution.Cu^2 ＋ can be separated and enriched on-line by using a customer designed 1,5-diphenylcarbazone grafted silica gel micro-column coupled with flow injection technology.The determination conditions including the enrichment time,coil length,flow rates of sample,type of eluent,reaction medium,amounts of all reagents, reaction temperature and effects of external ions,were optimized.Under these conditions,the linear range of the concentration determination curve is 0.0010～0.60 mg/L and the detection limit is 7.9×10^-4 mg/L.The sensitivity was improved by 20 times and the permitted amounts of some external ions were enhanced at least 10 times than that of a non-preconcentrated step method.The relative standard deviation of eleven replicate measurements is less than 2.6% .One assay cycle only takes 6 min and the total volume of reagents consumed is 6.0 mL.This established method has been applied for the determination of trace amounts of copper in Chinese traditional medicine and tea.