火焰原子吸收光谱法测定金属钾中微量钙

Determination of Calcium in Potassium by Flame Atomic Absorption Spectroscopy

研究和建立了金属钾中钙的分析方法。该法通过真空蒸馏分离基体钾,王水溶解蒸馏残渣,将王水蒸发至干后,用稀盐酸提取残渣制成样品溶液,用火焰原子吸收光谱仪进行测定。优化了仪器的工作参数,对蒸馏条件、残渣提取效果和干扰因素进行了系统研究。确定了在3×10-3 Pa和275℃下蒸馏钾,蒸馏速率为约2 g/h。发现残渣中钾对钙的测定存在一定干扰,采取在标准溶液中加入300μg/mL的钾进行匹配的方法消除了残留钾的干扰。向5~7 g金属钾中加入1~20μg/g钙获得的平均回收率为96.2%,相对标准偏差为6.2%,此方法的准确度和精密度均能满足检测要求。

A analytical method was developed to determinate calcium in potassium.In the method,the matrix potassium was removed by vacuum distillation,and the residues were dissolved by aqua regia,then aqua regia was evaporated until almost dry.The sample solution was made from the residues which were extracted with dilute hydrochloric acid and then determined by flame atomic absorption spectroscopy.The instrument parameters were optimized,and the distillation conditions,the effect of the residues extraction and the measuring interference factors were studies systemically.The distillation rate was determined to be about 2 g/h at 3×10-3 Pa and 275℃.The results show that the determination of calcium is interfered by potassium in the residues,and 300μg/mL potassium is added to standard solutions to eliminate the interference of potassium in the determination of calcium.The recovery percentage for 1~20μg/g calcium in 5~7 g potassium is 96.2%.The relative standard deviation is 6.2%.The accuracy and precision of this method can satisfy the determination requirements.