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测氯化铷、铯(或铬酸铷、铯)中微量锂,由于基体允许量受到一定的限制,目前大多采用标准加入法或比较法。萃取分离后测定锂,可以使试样的测定灵敏度达1×10~(-5)％。我们根据新名昭三综述的七种β-双酮对碱金属离子的萃取试验,确认了用二苯甲酰基甲烷(DBM)为最优,可萃取百分之百的锂。而铷、铯、铬酸根离子很少被萃取,检出限为0.5ppm,相对误差<±6％。 DBM对大多数金属离子达到萃取平衡比较慢,而对锂离子仅需一分钟,利于锂的分离。实验中得出溶剂给予体的能力按以下顺序增加:苯<乙醚<醋酸正丁酯<磷酸三丁酯。萃取能力按Li>Na>K>Rb>Cs的顺序减少。确定了在0.06N NaOH介质中,用0.1MDBM-10％磷酸三丁酯-90％煤油溶剂为最优。排除了由于TBP粘度大造成的直接雾化的困难,省略了反萃取这一步骤。为避免有些离子在碱性溶液中沉淀,加入一些酒石酸盐作掩蔽剂。
Determination of rubidium chloride, cesium (or rubidium chromate, cesium) trace of lithium, due to the amount of substrate to be subject to certain restrictions, the current most of the standard addition or comparison method. Determination of lithium extraction and separation, the sample can be measured sensitivity of 1 × 10 ~ (-5)%. According to the new name XIAO three extraction of seven β-diketone alkali metal ions, we confirmed that with dibenzoylmethane (DBM) is optimal, can extract one hundred percent lithium. Rubidium, cesium, chromate ions are rarely extracted, the detection limit of 0.5ppm, the relative error of <± 6%. DBM to extract the balance of most metal ions to achieve relatively slow, but only one minute for lithium ions, which will help the separation of lithium. The ability of the solvent donor to be obtained experimentally was increased in the following order: benzene Na> K> Rb> Cs. It was determined that 0.1MDBM-10% tributyl phosphate-90% kerosene solvent was optimal in 0.06N NaOH medium. The difficulty of direct atomization due to the high viscosity of TBP was ruled out and the step of stripping was omitted. To avoid precipitation of some ions in alkaline solution, add some tartrate as masking agent.