The ion selective electrode - reverse Gran graphics was proposed for the determination of fluorine ion in testing solution by adding the testing solution containing fluorine ion into standard solution of fluorine ion and was applied to the determination of fluorine ion concentration in AZ91D magnesium alloy micro-arc oxidation decay electrolyte. The interference ion and elimination method test indicated that, Zn2+ , Cu2+ , Ni2+ and Fe3+ from magnesium alloy matrix into strongly alkaline micro-arc oxidation electrolyte could be removed in form of precipitae. The interference of Mg2+ and Al3+ could be eliminated using ionic strength reagent TISAB. The SiO32- and excessive Al3+ were masked with C4O6H2KNa and EDTA. OH- . Na+ and K+ in solution did not interfere in the determination of fluorine. The proposed method was applied to the determination of fluorine ion concentration in aged magnesium alloy micro-arc oxidation electrolyte with recoveries of 99. 7 % —101. 9 %. The fluorine ion concentration in micro-arc oxidation decay electrolyte of two magnesium alloy samples was determined by this method and ion selective electrode-standard curve method. The precision and accuracy of determination results were analyzed. It indicated that the precision of this method was better than that of ion selective electrode-standard curve method. The correctness of two methods was consistent. The proposed method could be applied to the direct determination of fluorine ion in complicated solution system containing fluorine ion mass concentration higher than 1. 9 g/L.%提出了一种将含氟的待测液加到氟离子标准溶液中以测定待测液中氟离子的方法——离子选择性电极-逆格氏作图法,并用此法测定了AZ91D镁合金微弧氧化衰变电解液中氟离子浓度.待测试液中干扰离子和干扰的消除方法研究表明,从镁合金基体迁移到强碱性微弧氧化电解液中的Zn2+、Cu2+、Ni2+和Fe3+离子均以沉淀形式被过滤除去,Mg2+、Al3+等离子的干扰以离子强度剂TISAB消除,SiO32-和多余的Al3+离子分别用C4O6H2KNa和EDTA掩蔽,溶液中的OH-、Na+和K+均不干扰氟的测定.用本法测定了老化的镁合金微孤氧化电解液中的氟离子浓度,加标回收率在99.7％～101.9％之间.用本法和离子选择性电极-标准曲线法对两种镁合金试样的微弧氧化电解液中的氟离子浓度分别进行测定并对测定结果的精密度和准确度进行分析,表明本法的精密度比离子选择性电极—标准曲线法有所提高,而两种方法的正确度一致.本法可用于氟离子质量浓度高于1.9 g/L的复杂溶液体系中氟离子的直接测定.
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