论文部分内容阅读
介绍了一种基于Cr(Ⅲ)-二亚乙基三胺五乙酸(DTPA)-NO3-体系的催化作用测定溶液中铬(Ⅵ)和无机态铬(Ⅲ)的方法。制作了银汞合金电极,并在其表面通过自组装修饰上DTPA。在含有0.1mol/LHAc-NaAc(pH=5.5)缓冲液和0.25mol/L KNO3溶液中,当电极电位在-0.80~-1.40V间进行阴极化扫描时,溶液中Cr6+在电极表面被还原成为Cr3+并与电极表面上的DTPA络合,同时溶液中无机态铬(Ⅲ)也与DTPA络合,于-1.24V左右形成灵敏的还原峰。通过改变扫描前富集方式,分别实现铬(Ⅵ)和无机态铬(Ⅲ)的测定。铬(Ⅵ)和无机态铬(Ⅲ)的线性范围分别为:5.0×10-9~5.0×10-6mol/L和1.0×10-8~5.0×10-6mol/L,检测限为1.6×10-10mol/L和5.1×10-9mol/L。对溶液进行11次平行测定相对标准偏差为4.3%。该法用于实际水样测定,Cr(VI)和Cr(Ⅲ)的标准加入回收率为98.5%~105.0%。
A method for the determination of chromium (Ⅵ) and inorganic chromium (Ⅲ) based on the catalytic action of Cr (Ⅲ) -diethylenetriaminepentaacetic acid (DTPA) -NO3- system was introduced. Silver amalgam electrodes were fabricated and modified on their surface by DTPA. In the solution containing 0.1 mol / L HAc-NaAc (pH = 5.5) and 0.25 mol / L KNO3, when the electrode potential is between -0.80 and -1.40 V, the Cr6 + in the solution is reduced to Cr3 + and complexed with DTPA on the surface of electrode, meanwhile, Cr (Ⅲ) in solution also complexed with DTPA to form a sensitive reduction peak at -1.24V. The determination of chromium (Ⅵ) and inorganic chromium (Ⅲ) were achieved by changing the pre-scanning enrichment mode. The linear ranges of chromium (Ⅵ) and inorganic chromium (Ⅲ) were 5.0 × 10-9 ~ 5.0 × 10-6mol / L and 1.0 × 10-8 ~ 5.0 × 10-6mol / L respectively. The detection limit was 1.6 × 10-10 mol / L and 5.1 × 10-9 mol / L. The relative standard deviation of 11 parallel determinations of the solution was 4.3%. The method was applied to the actual determination of water samples. The standard recoveries of Cr (VI) and Cr (III) were 98.5% -105.0%.