KIO_4-四硼酸钠系统阻抑亮绿褪色动力学光度法测定痕量Ir(Ⅳ)  

Potassium periodate-sodium borate system inhibition kinetic spectrophotometric determination of trace bright green fading Iridium(Ⅳ)

作　　者：王洪福[1] 苏智先 张素兰[3] 罗英[3] 杨聪[1] 

机构地区：[1]绵阳师范学院化学与化学工程学院,绵阳621000 [2]生态与环境保护四川省重点实验室,绵阳621000 [3]绵阳师范学院生命科学与技术学院,绵阳621000

出　　处：《分析试验室》2012年第2期101-104,共4页Chinese Journal of Analysis Laboratory

摘　　要：基于H2SO4介质及四硼酸钠缓冲溶液中,80℃水浴中,Ir(Ⅳ)对KIO4氧化亮绿褪色反应具有阻抑作用,据此建立了阻抑动力学光度法测定痕量Ir(Ⅳ)的新方法。阻抑反应(吸光度A)与非阻抑反应(吸光度A0)吸光度差值△A与Ir(Ⅳ)的质量浓度ρ在0.0002～0.08μg/mL范围内呈良好的线性关系,检出限为2.969×10-10g/mL。对1μg/25 mL Ir(Ⅳ)标准溶液测定的相对标准偏差为1.7%(n=11)。测定了动力学参数,反应对Ir(Ⅳ)为一级反应,试验条件下,总反应为准一级反应,表观速率系数为2.883×10-4/s,表观活化能为52.2 kJ/mol。方法用于分子筛和活性炭样品中痕量Ir(Ⅳ)测定,加标回收率在98.1%～104.9%范围,符合痕量分析要求。On condition of heating to 80℃ and diluted sulfuric acid used as medium and sodium tetraborate as buffer,the fading reaction of potassium periodate oxidizing bright green could be inhibited by iridium（Ⅳ）,and a inhibitory kinetic spectrophotometry of trace iridium determination was established based on that in this paper.The absorbency difference △A between inhibitory reaction and non-inhibitory reaction remained good linear relationship with mass concentrationρ of iridium（Ⅳ） in the range of 0.0002～0.08 μg / mL.The detection limit was 2.969×10-10 g /mL.The relative standard deviation of 1μg/25 mL iridium（Ⅳ） standard solution was 1.7 %（n = 11）.Kinetic parameters were determined and the inhibitory reaction to iridium（Ⅳ） was first order while the whole reaction was pseudo first order.The apparent rate constant was 2.883×10-4 /s and apparent active energy was 52.2 kJ/mol.The recoveries of this method were in the range of 98%～105% when applied to the determination of trace iridium（Ⅳ） in molecular sieve and active carbon samples,and it fulfilled the requirements of trace analysis.

关 键 词：Ir(Ⅳ) 亮绿 催化动力学光度法 四硼酸钠 分子筛 

分 类 号：O657.3[理学—分析化学]