萃取分析时最低掩蔽剂浓度的简便计算方法

提出一种萃取分析时掩蔽剂最低浓度的简便计算公式:lgR]=1blgKe+nlgHLn(o)]+npH-lgβb+3+lgVV((wo))],式中Ke为干扰金属离子与萃取剂配合物的萃取平衡常数,HLn(o)]为萃取剂在有机相的浓度,V(o)和V(w)分别为有机相和水相的体积,n、b分别为干扰金属离子与萃取剂配合物的最大配位数和溶液中干扰金属离子与掩蔽剂配合物浓度最大配离子的级数。β为干扰金属离子与掩蔽剂配合物的累积稳定常数。求解时,我们从第一级配离子浓度最大开始,若计算出的R]位于第一级配离子浓度最大的自由配体浓度范围,则此时的R]即为计算结果;否则试探下一级配离子直至位于其浓度范围。得到了R]后,由酸效应系数可计算出掩蔽剂的最小浓度。

A Simple Method for Calculating the Minimum Concentration of Masking Agent in Extraction Determination

A simple equation for calculating the minimum concentration of masking agent in extraction determination was presented： lgR]= 1b lgKe ＋ nlgHLn（o） ]＋ npH-lgβb ＋ 3 ＋ lg VV（（wo）） ],where Ke was the extraction equilibrium coefficient of coordination compound formed by interfering metal ion and extraction agent,HLn（o） ]was concentration of extraction agent on the organic phase,V（o） 和 V（w） were volumes of organic and water phases,respectively,n,b were the maximum coordination number of coordination compound formed by interfering metal ion and extraction agent and the coordination number of coordination ion formed by interfering metal ion and masking agent with maximum concentration.β was accumulative stability constant of coordination compound formed by interfering metal ion and masking agent.A test method was presented to solve the equation.The first coordination ion of coordination compound formed by interfering metal ion and masking agent was the one with the maximum concentration,if R]calculated from above equation was at the concentration range which the first coordination ion was the one with maximum concentration,then the R]was the calculation result.And the next coordination ion was continuous to be chosen as the one with maximum concentration until the calculated R]was at its range.The minimum concentration of masking agent can be obtained from acidity coefficient of masking agent.