【摘要】 在含ＥＤＴＡ、溴代苯羟乙酸（Ｂｒ－ＢＨＡ）的硫－磷混酸介质中，钼（Ⅵ）、钨（Ⅵ）－Ｂｒ－ＢＨＡ络合物分别在- ０.５０Ｖ和-０．８７Ｖ（ｖｓ．ＳＣＥ）处产生不太灵敏的极谱电流。加入ＮａＣｌ_３后，产生灵敏催化电流［比在苯羟乙酸（ＢＨＡ）体系分别增敏２．３倍和３倍］，峰电位（Ｅｐ）分别移至－０.４４Ｖ和－０.７８Ｖ。系统研究了十余种易质子化有机染料和八种阳离子表面活性剂对上述催化电流进一步增敏效应，其中以亚甲蓝（ＭＢ）为最佳。无ＮａＣｌＯ_３时，加入 ＭＢ，原络合电流略有所降低， Ｅｐ无明显变化。但当加入 ＮａＣｌＯ_３后，极谱催化电流得到进一步增敏， Ｅｐ分别为-０.４３Ｖ和-０．８３Ｖ。钼（Ⅵ）、钨（Ⅵ）测定的线性范围分别为２×１０^－９～４×１０^－７和５×１０^-１０～２×１０^-８ｍｏｌ／Ｌ，检出限分别为１×１０^-９和３×１０^－１０ｍｏｌ／Ｌ。大多共存离子（阳离子４４种，阴离子１０种）不干扰测定，［Ｍｏ（Ⅵ）］：［Ｗ（Ⅵ）］或反之，为１：２５００互不干扰。方法已用于合金、纯铁等样品中铝、钨的同时直接测定，结果满意。有关络合物、电极反应和增敏机理等研究结果，将另文发表。更多还原

【Abstract】 In the medium of surfuric acid and phosphoric acid（S-P） mixed in 1+1, containing p-bromo benzene hydroxyacetic acid（Br BHA）, EDTA, the polarographic currents observed at-0.50V（vs.SCE） [for Mo（Ⅵ）] and -0.87V [for W（Ⅵ）] were not so sensitive. But in the presence of NaClO₃, the very sensitive catalytic currents appeared at -0.44V [for Mo（Ⅵ）] and -0.78V [for W（Ⅵ）] respectively.A possibility of these catalytic currents mentioned above further enhanced by protonated organic dyes or by cationic surfactants has been investigated. Among them the methylene blue （MB） was the best one, which has the lowest detection limit both for Mo （Ⅵ） （1× 10-9mol/L） and W （Ⅵ） (3×10^-10mol/L). After adding an appropriate amount of MB, the catalytic currents for Mo（Ⅵ） and W（Ⅵ） were further increased significantly, and Ep was shifted to -0.43V for Mo（Ⅵ） and to -0.83V for W（Ⅵ） respectively. The responses for Mo （Ⅵ） and for W（Ⅵ） were linear over the range of 2×10^-9 to 4×10^-7mol/L and 5×10^-10 to 2×10^-8mol/L respectively. Most coexisting ions（44 cations, 10 anions） studied did not interfere with the determination of Mo（Ⅵ） and W（Ⅵ）, and the allowable proportion of Mo（Ⅵ） to W（Ⅵ） or in the reverse both was 1:25000. The proposed method has been applied to determine the molybdenum and tungsten in alloys simultaneously and directly with satisfactory results.更多还原