偶氮氯膦2mA2鋨2高碘酸鉀催化光度法測(cè)定微量鋨

1、偶氮氯膦2mA 2鋨2高碘酸鉀催化光度法測(cè)定微量鋨許紅平33李江33陳興國3胡之德(蘭州大學(xué)化學(xué)化工學(xué)院,蘭州730000摘要在堿性介質(zhì)中,鋨對(duì)KI O 4氧化偶氮氯膦2mA 的褪色反應(yīng)有明顯的催化作用,據(jù)此建立了催化光度法測(cè)定微量鋨的新方法,并用正交實(shí)驗(yàn)設(shè)計(jì)對(duì)反應(yīng)條件進(jìn)行了優(yōu)化。方法的檢測(cè)限為2.0g/L 。鋨含量在7.025.0g/L 范圍內(nèi)服從比爾定律。此方法已用于貴金屬精礦和二次合金中微量鋨的測(cè)定,相對(duì)誤差均為0.9%,回收率在95.38%106.0%之間。關(guān)鍵詞鋨,偶氮氯膦2mA ,催化光度法,正交實(shí)驗(yàn)設(shè)計(jì)2000206213收稿;2000211208接受33寧夏醫(yī)學(xué)院化學(xué)教研室,銀

2、川7500041引言含膦或胂酸基的變色酸雙偶氮衍生物作為顯色劑在光度分析中得到廣泛的應(yīng)用1,偶氮氯膦2mA (CPA 2mA 即是一種良好的變色酸雙偶氮氯膦類的衍生物,自1979年合成以來,已廣泛用于稀土、鈣、鉍、鈦、鋯、銅、鐵等多種元素的測(cè)定2,3,但用于測(cè)定鋨的分析方法尚未見報(bào)道。試驗(yàn)表明,在堿性介質(zhì)中微量Os 對(duì)KI O 4與偶氮氯膦2mA 的氧化褪色反應(yīng)有明顯的催化作用,利用此現(xiàn)象建立了測(cè)定微量鋨的催化光度新方法,并用正交實(shí)驗(yàn)設(shè)計(jì)表L 25(56對(duì)實(shí)驗(yàn)條件進(jìn)行了設(shè)計(jì)和優(yōu)化4。該方法已成功地用于貴金屬精礦和二次合金中微量鋨的測(cè)定并獲得滿意的結(jié)果。2實(shí)驗(yàn)部分2.1試劑和儀器Os 標(biāo)準(zhǔn)溶液:

3、用(NH 42OsCl 6按常規(guī)方法配制0.1000g/L 儲(chǔ)備液,使用時(shí)用水稀釋為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 。所有試劑均為分析純。721型分光光度計(jì)(四川分析儀器廠。2.2實(shí)驗(yàn)方法準(zhǔn)確移取一定量鋨標(biāo)準(zhǔn)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 ,用水稀釋至刻度、搖勻,在沸水浴中加

4、熱2min 后取出,流水冷卻至室溫,用0.5cm 比色皿于580nm 處以蒸餾水為參比,分別測(cè)定非催化反應(yīng)的吸光度(A 非和催化褪色反應(yīng)的吸光度(A 催,依據(jù)式A =A 非-A 催計(jì)算A 。3結(jié)果與討論3.1吸收曲線實(shí)驗(yàn)表明,CPA 2mA 在NaOH 介質(zhì)中的最大吸收波長為580nm 。3.2反應(yīng)條件的選擇以NaOH 溶液用量、CPA 2mA 溶液用量、KI O 4溶液用量和沸水浴加熱時(shí)間為考察因素,采用正交實(shí)驗(yàn)設(shè)計(jì)對(duì)反應(yīng)條件進(jìn)行優(yōu)化。實(shí)驗(yàn)安排及結(jié)果見表1。用極差分析法對(duì)測(cè)試結(jié)果進(jìn)行分析,結(jié)果表明,B (CPA 2mA 的極差R (0.318在四個(gè)考查因素中最大,因此CPA 2mA 用量是影

5、響反應(yīng)條件最主要的因素。計(jì)算各因素在各水平下測(cè)試結(jié)果的平均值,各因素在各水平下測(cè)試結(jié)果的平均值最大的為:A (NaOH 為第29卷2001年5月分析化學(xué)(FE NXI H UAX UE 研究簡(jiǎn)報(bào)Chinese Journal of Analytical Chemistry 第5期546548R 3(0.312、B (CPA 2mA 為R 5(0.430、C (KI O 4為R 4(0.287和D (加熱時(shí)間為R 3(0.337,所以最佳反應(yīng)條件為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 和沸水浴加熱2min 。表1正交實(shí)驗(yàn)結(jié)果T able 1Orthog onal experimental design序號(hào)N o.(1A0.10m ol/L NaOH體積(m L V olume(2B0.030%(W/V CPA 2mA 體積(m L V olume(3C 1.0×10-2m ol/L K IO 4體積(m L V olume(5D加熱時(shí)間(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干擾離子的影響在實(shí)驗(yàn)條件下,測(cè)定誤差為±5%時(shí),對(duì)于0.02mg/L Os ,下列離子(mg/L 不干擾測(cè)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。由此可見,Ru 和Ir 對(duì)Os 的測(cè)定有嚴(yán)重干擾,將Os 通過選擇性蒸餾后可消除其干擾。3.4標(biāo)準(zhǔn)曲線在最佳條件下,該催化光度法測(cè)定Os 的檢測(cè)限為2.0g/L ,在7.025.0g/L 范圍內(nèi)符合比爾定律,標(biāo)準(zhǔn)曲線的線性回歸方程為A =0.1428+27.52C (mg/L ,R =0.9938。3.5樣品分析貴金屬精礦的處理見文獻(xiàn)5。分析二次合金樣品時(shí),先在一定量二次合金樣品中加入10m L HCl 于電爐上加熱40min ,重復(fù)此操作一次,再加入5m L H NO

11、3并加熱至樣品完全溶解,冷卻后采用與貴金屬精礦同樣的選擇性蒸餾方法將OsO 4蒸出并用適量NaBH 4還原至Os 、稀釋至一定體積即得到樣品745第5期許紅平等:偶氮氯膦2mA 2鋨2高碘酸鉀催化光度法測(cè)定微量鋨溶液。吸取適量樣品溶液,按實(shí)驗(yàn)方法測(cè)定鋨含量,測(cè)定結(jié)果見表2。由表2可見,本法測(cè)定結(jié)果令人滿意。表2貴金屬精礦和二次合金中鋨的含量測(cè)定結(jié)果T able2Determination results of osmium in concentrate of noble metals and secondary alloy樣品Sam ples推薦值Recommended value(mg/L本

12、法結(jié)果The present method(mg/L相對(duì)誤差RE(%RS D3(%加入量Added(mg/L回收率Recovery(%貴金屬精礦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(張華山,Li X inyi(黎心懿.Chemical Reagents(化學(xué)試劑,1989,11(6:327332

13、:3232K ai X iaoming(開小明,Wang Chengli(汪呈理,Zhang Qun(張群,Li Shanxiang(李善祥.Metallurgical Analysis(冶金分析,1996,16(4:39403Y ang Jinping(楊錦萍.Physical Testing and Chemical Analysis,Part B:Chemical Analysis(理化檢驗(yàn)2化學(xué)分冊(cè),1995,31(2:91924Analytical Chemistry Section of Hangzhou University(杭州大學(xué)化學(xué)系分析化學(xué)教研室編.Handbook o

14、f Analytical Chemistry (Part1(分析化學(xué)手冊(cè)第一分冊(cè),(2nd Edition第二版,Beijing(北京:Chemical Industry Press(化學(xué)工業(yè)出版社, 1997:6245K ou Z ongyan(寇宗燕,Liu X ilin(劉錫林,Chen X ingguo(陳興國,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