双波长分光光度法测定土壤中微量碘  

Double-wavelength spectrophotometric determination of micro iodine in soil

作　　者：李人宇[1,2] 李咏梅[2] 周家宏[3] 韦芳[1] 

机构地区：[1]连云港师范高等专科学校,江苏连云港222006 [2]淮海工学院江苏省海洋资源开发研究院,江苏连云港222005 [3]南京师范大学分析测试中心,江苏南京210097

出　　处：《冶金分析》2009年第7期53-57,共5页Metallurgical Analysis

基　　金：国家自然科学基金项目(20603018);连云港市科技项目(SH0816;CN0646)资助;江苏省海洋资源开发研究院科技开放基金项目(JSIMR09C08)资助

摘　　要：聚乙烯醇（PVA-124）存在下，在PH4．5的乙酸-乙酸钠缓冲溶液中，I^--Ag^＋的沉淀反应会促进Ag^＋-邻菲哆啉-曙红Y离子缔合物的离解，514nm处出现正吸收峰，548nm处出现负吸收峰。选定测量波长为514nm，参比波长为548nm，实现了双波长分光光度法测定微量碘。试验了酸度、试剂用量、稳定剂、试剂加入顺序、温度和时间的影响，确定了最佳测定条件。采用732型阳离子交换树脂分离去除Co^2＋，Fe^3＋，Zn^2＋等金属离子，加入抗坏血酸消除氧化性离子的干扰。线性范围为0．05～0．4μg／mL，ε=1．18×10^5L·mol^-1·cm^-1，检出限为26．2μg／L。方法用于测定连云港市滨海盐土和棕壤中碘，结果与离子色谱法一致，相对标准偏差分别为1．6％和1．9％（n=5），回收率为97％～99％。A new method for the determination of micro iodine by double-wavelength spectrophotometry with 514 nm as the measureing wavelength and 548 nm as the reference wavelength was developed. In the presence of PVA-124, dissociation of the ion-association complex of Ag^＋-phen-eosin Y was accelerated by the deposition reaction between I^- and Ag^＋ in acetate buffer solution at pH 4.5, resulting in a positive absorption peak at 514 nm and a negative absorption peak at 548 nm. The optimal conditions of measurements of iodine including acidity, reagent dosage, stabilizer, reagent adding sequence, temperature and time were studied. The metal ions, i. e. , Co^2＋ ,Fe^3＋ ,Zn^2＋ could be separated by 732-type cation exchange resin, and the interferences of oxidative ions could be eliminated by adding ascorbic acid. The linear range of the determination of iodine was 0.05--0. 4μg/mL. The apparent molar absorptivity was 1.18× 10^5 L · mol^-1 · cm^-1 , and the detection limit was 26.2 μg/L. The method was applied to determine iodine in seashore salines and brown soil samples from Lianyungang city. The results showed good agreement with those obtained by ion chromatography （IC）. RSDs were 1.6 % and 1.9 % （n = 5）, respectively. Recoveries were found to be 97 %--99 %.

关 键 词：双波长分光光度法 碘 银(I) 邻菲啰啉 曙红Y 

分 类 号：O657.32[理学—分析化学]