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研究了W(Ⅵ)与Tiron的显色反应,在pH=4.5的HAc-NaAc介质中,它们形成一种稳定的无色配合物,组成为1:1。该配合物在251nm和312nm处有较强的紫外吸收峰,测得ε_(251)=5.7×10~3,ε_(312)=7.7×10~3,据此建立了测定W(VI)的紫外分光光度法。在251nm和312nm处的线性范围均为2.0×10~(-6)～2.0×~(-4)mol·L~(-1)(0.37～37mg/L),检出限分别为0.37mg/L和0.18mg/L,SiO_3~(2-)及少量PO_4~(3-)的存在不干扰测定,Mo(Ⅵ)、V(Ⅴ)、Fe(Ⅲ)等对测定有干扰,该法试用于几种杂多酸样品的测定,结果满意,方法回收率为95～106％,变异系数≤0.4％(n=5)。
The color reaction of W (Ⅵ) with Tiron was studied. In the HAc-NaAc medium at pH = 4.5, they formed a stable, colorless complex with a 1: 1 composition. The complexes have strong UV absorption peaks at 251nm and 312nm. The results showed that ε_ (251) = 5.7 × 10 ~ 3 and ε_ (312) = 7.7 × 10 ~ 3. UV spectrophotometry. The linear range was 2.0 × 10 -6 ~ 2.0 × -4 mol·L -1 (0.37 ~ 37 mg / L) at 251 nm and 312 nm with the detection limits of 0.37 mg / L and 0.18mg / L, SiO 3 2- and a small amount of PO 4 3- did not interfere with the determination. Mo (Ⅵ), V (Ⅴ) and Fe (Ⅲ) The results of several heteropoly acid samples were satisfactory. The recoveries were 95% ~ 106% and the coefficients of variation were ≤0.4% (n = 5).