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

1.在邻苯二胺存在下，铜催化抗坏血酸氧化，建立了测定铜形态的催化光度法。铜的反应物种的特点是通过络合研究的亚铜物种。研究表明，反应态铜的存在形式为Cu^&lt;2+&gt;和Cu^<II>L_n（单齿配体n = 2，双齿配体n=1）。2.用于形态分析的流动系统的仪器化在测定反应态铜时，流动系统所用的PTFE管内壁吸附铜，严重干扰测定。具有用于每种试剂和样品溶液的单独流动管线的歧管以及具有铝的载体溶液有效地抑制了铜的吸附。铜的测定误差为1 ng/ml，采样频率为6个样品/h。腐殖物质荧光测定的流动线与铜的流动系统相结合。作为腐殖酸，腐殖酸类物质的同时测定高达200 ng/ml，误差为10 ng/ml。3.应用所提出的分析系统应用于人工河水样品中铜和腐殖酸在铝存在下的形态分析，该样品含有铜（II）、腐殖酸、铁（III）和硅酸盐。活性铜和腐殖酸浓度的降低表明含铜腐殖酸聚集体的形成。在铝的存在下，氟离子的效果也进行了研究，为同一个人工样品。

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.