偶氮氯膦2mA2锇2高碘酸钾催化光度法测定微量锇

1、偶氮氯膦2mA 2锇2高碘酸钾催化光度法测定微量锇许红平33李江33陈兴国3胡之德(兰州大学化学化工学院,兰州730000摘要在碱性介质中,锇对KI O 4氧化偶氮氯膦2mA 的褪色反应有明显的催化作用,据此建立了催化光度法测定微量锇的新方法,并用正交实验设计对反应条件进行了优化。方法的检测限为2.0g/L 。锇含量在7.025.0g/L 范围内服从比尔定律。此方法已用于贵金属精矿和二次合金中微量锇的测定,相对误差均为0.9%,回收率在95.38%106.0%之间。关键词锇,偶氮氯膦2mA ,催化光度法,正交实验设计2000206213收稿;2000211208接受33宁夏医学院化学教研室,银

2、川7500041引言含膦或胂酸基的变色酸双偶氮衍生物作为显色剂在光度分析中得到广泛的应用1,偶氮氯膦2mA (CPA 2mA 即是一种良好的变色酸双偶氮氯膦类的衍生物,自1979年合成以来,已广泛用于稀土、钙、铋、钛、锆、铜、铁等多种元素的测定2,3,但用于测定锇的分析方法尚未见报道。试验表明,在碱性介质中微量Os 对KI O 4与偶氮氯膦2mA 的氧化褪色反应有明显的催化作用,利用此现象建立了测定微量锇的催化光度新方法,并用正交实验设计表L 25(56对实验条件进行了设计和优化4。该方法已成功地用于贵金属精矿和二次合金中微量锇的测定并获得满意的结果。2实验部分2.1试剂和仪器Os 标准溶液:

3、用(NH 42OsCl 6按常规方法配制0.1000g/L 储备液,使用时用水稀释为1.000mg/L ;KI O 4溶液:1.0×10-2m ol/L ,NaOH 溶液:0.10m ol/L ;CPA 2mA 溶液:0.030%(W/V 。所有试剂均为分析纯。721型分光光度计(四川分析仪器厂。2.2实验方法准确移取一定量锇标准溶液于10m L 比色管中,依次加入0.10m ol/L NaOH 溶液0.20m L 、01030%(W/V CPA 2mA 溶液2.50m L 、1.0×10-2m ol/L KI O 4溶液3.00m L ,用水稀释至刻度、摇匀,在沸水浴中加

4、热2min 后取出,流水冷却至室温,用0.5cm 比色皿于580nm 处以蒸馏水为参比,分别测定非催化反应的吸光度(A 非和催化褪色反应的吸光度(A 催,依据式A =A 非-A 催计算A 。3结果与讨论3.1吸收曲线实验表明,CPA 2mA 在NaOH 介质中的最大吸收波长为580nm 。3.2反应条件的选择以NaOH 溶液用量、CPA 2mA 溶液用量、KI O 4溶液用量和沸水浴加热时间为考察因素,采用正交实验设计对反应条件进行优化。实验安排及结果见表1。用极差分析法对测试结果进行分析,结果表明,B (CPA 2mA 的极差R (0.318在四个考查因素中最大,因此CPA 2mA 用量是影

5、响反应条件最主要的因素。计算各因素在各水平下测试结果的平均值,各因素在各水平下测试结果的平均值最大的为:A (NaOH 为第29卷2001年5月分析化学(FE NXI H UAX UE 研究简报Chinese Journal of Analytical Chemistry 第5期546548R 3(0.312、B (CPA 2mA 为R 5(0.430、C (KI O 4为R 4(0.287和D (加热时间为R 3(0.337,所以最佳反应条件为A 3B 5C 4D 3即0.10m ol/L NaOH 溶液0.20m L 、0.030%(W/V CPA 2mA 溶液2.50m L 、1.0&#

6、215;10-2m ol/L KI O 4溶液3.00m L 和沸水浴加热2min 。表1正交实验结果T able 1Orthog onal experimental design序号N o.(1A0.10m ol/L NaOH体积(m L V olume(2B0.030%(W/V CPA 2mA 体积(m L V olume(3C 1.0×10-2m ol/L K IO 4体积(m L V olume(5D加热时间(s T imeA1(10.05(10.50(10.50(1600.0302(10.05(21.00(21.00(2900.1263(10.05(31.50(32.00(

7、31200.2354(10.05(42.00(43.00(41500.3355(10.05(52.50(54.00(51900.0006(20.10(10.50(21.00(41500.1727(20.10(21.00(32.00(51900.3238(20.10(31.50(43.00(1600.0509(20.10(42.00(54.00(2900.09010(20.10(52.50(10.50(31200.64011(30.20(10.50(32.00(2900.11012(30.20(21.00(43.00(31200.33013(30.20(31.50(54.00(41500.454

8、14(30.20(42.00(10.50(51900.33615(30.20(52.50(21.00(1600.33016(40.40(10.50(43.00(51900.15817(40.40(21.00(54.00(1600.05518(40.40(31.50(10.50(2900.15219(40.40(42.00(21.00(31200.39020(40.40(52.50(32.00(41500.61921(50.60(10.50(54.00(31200.08822(50.60(21.00(10.50(41500.09523(50.60(31.50(21.00(51900.25724(

9、50.60(42.00(32.00(1600.13825(50.60(52.50(43.00(2900.560R 10.1450.1120.2510.121R 20.2550.1860.2550.208R 30.3120.2300.2850.337R 40.2750.2580.2870.301R 50.2280.4300.1370.215R0.1670.3180.1500.2163.3干扰离子的影响在实验条件下,测定误差为±5%时,对于0.02mg/L Os ,下列离子(mg/L 不干扰测定:K 140、Na 50、Pb 15、Hg 10、Pd 10、Al 5、Ni 4、Rh 2、C

10、r 1.5、Cu 1.2、Mg 1.2、Ca 1、Zn 1、C o 1、Pt 1、Mn 1、Ru 0.02和Ir 0.02。由此可见,Ru 和Ir 对Os 的测定有严重干扰,将Os 通过选择性蒸馏后可消除其干扰。3.4标准曲线在最佳条件下,该催化光度法测定Os 的检测限为2.0g/L ,在7.025.0g/L 范围内符合比尔定律,标准曲线的线性回归方程为A =0.1428+27.52C (mg/L ,R =0.9938。3.5样品分析贵金属精矿的处理见文献5。分析二次合金样品时,先在一定量二次合金样品中加入10m L HCl 于电炉上加热40min ,重复此操作一次,再加入5m L H NO

11、3并加热至样品完全溶解,冷却后采用与贵金属精矿同样的选择性蒸馏方法将OsO 4蒸出并用适量NaBH 4还原至Os 、稀释至一定体积即得到样品745第5期许红平等:偶氮氯膦2mA 2锇2高碘酸钾催化光度法测定微量锇溶液。吸取适量样品溶液,按实验方法测定锇含量,测定结果见表2。由表2可见,本法测定结果令人满意。表2贵金属精矿和二次合金中锇的含量测定结果T able2Determination results of osmium in concentrate of noble metals and secondary alloy样品Sam ples推荐值Recommended value(mg/L本

12、法结果The present method(mg/L相对误差RE(%RS D3(%加入量Added(mg/L回收率Recovery(%贵金属精矿C oncentrate of noble metals0.2240.2260.897.00.0050.0090.013106.0100.998.24二次合金Secondary alloy0.1180.1170.858.00.0050.0090.013100.0105.695.383n=6R eferences1Zhang Huashan(张华山,Li X inyi(黎心懿.Chemical Reagents(化学试剂,1989,11(6:327332

13、:3232K ai X iaoming(开小明,Wang Chengli(汪呈理,Zhang Qun(张群,Li Shanxiang(李善祥.Metallurgical Analysis(冶金分析,1996,16(4:39403Y ang Jinping(杨锦萍.Physical Testing and Chemical Analysis,Part B:Chemical Analysis(理化检验2化学分册,1995,31(2:91924Analytical Chemistry Section of Hangzhou University(杭州大学化学系分析化学教研室编.Handbook o

14、f Analytical Chemistry (Part1(分析化学手册第一分册,(2nd Edition第二版,Beijing(北京:Chemical Industry Press(化学工业出版社, 1997:6245K ou Z ongyan(寇宗燕,Liu X ilin(刘锡林,Chen X ingguo(陈兴国,Hu Zhide(胡之德.Metallurgical Analysis(冶金分析,1994,14(4:1820C atalytic Spectrophotometric Determination of OsmiumUsingOsmium2KIO42Chlorophosphon

15、azo2mA SystemXu H ongping,Li Jiang,Chen X ingguo3,Hu Zhide(College o f Chemistry and Chemical Engineering,Lanzhou Univer sity,Lanzhou730000AbstractA catalytic spectrophotometric method for the determination of micro am ounts of osmium has been established based on the catalytic action of Oson the ox

16、idation fading reaction of chlorophosphonazo2mA with KI O4 in alkaline2medium.The reaction conditions were optimized by orthog onal experimental design.The detection limit for osmium was2.0g/L.Beers law was obeyed in the range from7.0to25.0g/L for Os.The method has been applied to the determination of micro am ounts of Osin concentrate of nobl