论文部分内容阅读
建立了甘露醇选择性析出硼酸中与B(Ⅲ)等量的H+和pH-NaOH滴定B(Ⅲ)的新方法。系统地研究了难溶解贵金属-硼焊料中B的酸分解及其含量测定的条件。简述了H2SO4用量与Na盐量的关系及其对滴定的影响。比较了pH电极与指示剂对指示滴定终点的影响。讨论了提高测定B(Ⅲ)的准确度和精密度的条件。结果表明:采用自制简易回流装置,HNO3-H2SO4能完全分解样品中的B,并可避免B(Ⅲ)的挥发损失。于≤2.0mLH2SO4的滴定介质中,近终点NaOH微滴定和pH电极指示终点的方法,提高了滴定终点的敏锐度、分析结果的准确度和精密度。方法特点:分解完全,选择性好,准确度(测定2.00~12.00mg B,相对误差≤±0.50%)和精密度(测定4% B,相对平均误差-0.74%~+0.99%、相对标准偏差0.64%)高,操作简便,适用性强。已应用于B质量分数为1%~12%的难溶贵金属-硼焊料等样品中B的测定,结果满意。
A new method for the titration of H + and pH-NaOH B (Ⅲ) with B (Ⅲ) in boric acid was established. The conditions for the acid decomposition and content determination of B in the hardly soluble precious metal-boron solder were systematically studied. The relationship between the amount of H2SO4 and the amount of Na salt and its effect on titration are briefly described. The effect of the pH electrode and indicator on the endpoint of the titration was compared. The conditions for improving the accuracy and precision of the determination of B (III) are discussed. The results show that HNO3-H2SO4 can completely decompose B in the sample and avoid the loss of B (Ⅲ) by self-made simple reflux device. In ≤ 2.0mLH2SO4 titration medium, near the end of NaOH microtiter and pH electrode indicates the end of the method to improve the titration endpoint sensitivity, the accuracy and precision of the analysis results. The method has the characteristics of complete decomposition, good selectivity, accuracy (measured 2.00-12.00 mg B, relative error ≤ ± 0.50%) and precision (measured 4% B, relative average error -0.74% -0.99%, relative standard deviation 0.64%) high, easy to operate, applicability. Has been applied to the B mass fraction of 1% to 12% of the precious metals - boron solder samples B determination, with satisfactory results.