【摘要】 对络合滴定法测定混合成垢阳离子Ca2+、Mg2+、Ba2+、Sr2+总浓度和单一成垢阳离子Ba2+或Sr2+浓度所得结果的准确度进行了实验考察。当用石油天然气行业标准SY5523 92规定的EDTA直接络合滴定法测定4种阳离子总浓度时,随着水样中Mg2+浓度的降低,测定结果的相对平均偏差(精确度)变化不大,但相对误差(准确度)逐渐增大,Mg2+浓度为零时高达33.2%;用直接滴定法测定单一Ba2+或Sr2+浓度时,相对平均偏差较大,相对误差则很大。当混合阳离子中Mg2+浓度低或为零或测定单一Ba2+或Sr2+时,在一定量的Mg EDTA存在下用反滴定法可获得令人满意的测定结果。图4表3参3。更多还原

【Abstract】 The accurancy of determinations of total concentration of scaling cations Ca²⁺, Mg²⁺, Ba²⁺, and Sr²⁺ and of concentration of single cation Ba²⁺ or Sr²⁺ （by） EDTA-complexometric titration is studied experimentally. For the determinations of total concentration of the 4 cations obtained by direct titration, which is recommended for evaluating scale inhibitors in an oil/gas industry trade standard, SY 5523-93, with decreasing Mg²⁺ concentration the deviation from mean is less changeable but the relative error increases notably, being of 33.2% at null Mg²⁺ concentration. In determining single Ba²⁺ or Sr²⁺ by direct titration the deviation from mean of the determinations is not small and the relative error— very large. Satisfactory results of analysis can be obtained in the cases when Mg²⁺ concentration in the water samples containing mixed scaling cations is low or null or when single cation Ba²⁺ or Sr²⁺ is to be determined by using inverse complexometric titration at the presence of some amount of mg-EDTA.更多还原