Development of an analytical system for speciation of trace metals using catalytic reactions

1.建立了在邻苯二胺存在下，用铜催化抗坏血酸氧化法测定铜形态的催化分光光度法。通过草草酸与铜的络合研究，对铜的活性物质进行了表征。研究发现，铜的活性组分为Cu^<2+>和Cu^<II>L_n （n≤2，双齿配体为n=1）。在测定活性铜时，流动系统使用的聚四氟乙烯管内壁吸附铜，严重干扰测定。每个试剂和样品溶液都有单独的流线，铝载体溶液有效地抑制了铜的吸附。铜的测定误差为1 ng/ml，取样频率为6个样品/h。在铜的流动系统中加入了荧光法测定腐殖质的流动线。作为腐植酸，腐植酸类物质可同时测定200ng /ml，误差为10ng /ml。该分析系统应用于含铜（II）、腐植酸、铁（III）和硅酸盐的人工河水样中存在铝时铜和腐植酸的形态分析。活性铜和腐植酸浓度的降低表明形成了含铜的腐植酸聚集体。在铝存在的情况下，还研究了氟离子对同一人工样品的影响。

1.Determinable reactive speciesA catalytic spectrophotometric determination method for speciation of copper was developed using a copper-catalyzed oxidation of ascorbic acid in the presence of o-phenylenediamine. Reactive species of copper were characterized by a complexation study of oxalato-copper species. The study revealed that the reactive copper species were Cu^<2+> and Cu^<II>L_n (n≦2 for an unidentate and n=1 for bidentate ligand (L)).2.Instrumentation of flow system for speciation analysisFor determination of reactive copper, PTFE tube used for the flow system adsorbs copper on its inner wall and seriously interfered with the determination. A manifold with individual flow lines for each reagent and sample solutions and a carrier solution with aluminum effectively inhibited the adsorption of copper. Copper was determined with an error of 1 ng/ml and a sampling frequency of 6 samples/h. A flow line for fluorometric determination of humic substances was incorporated with the flow system for copper. As humic acid, humic substances were simultaneously determined up to 200 ng/ml with an error of 10 ng/ml.3.ApplicationThe proposed analytical system was applied to the speciation of copper and humic acid in the presence of aluminum in an artificial river water sample containing copper(II), humic acid, iron(III) and silicate. Decrease of concentrations of reactive copper and humic acid suggested the formation of humic aggregates containing copper. The effect of fluoride ions in the presence of aluminum was also studied for the same artificial sample.