将高钙食品置于瓷坩埚中,加入硝酸低温加热消解并蒸至近干,残渣用硝酸(1+1)溶液溶解,并补足至25 mL。采用石墨炉原子吸收光谱法测定试液中镉的含量。以硝酸镁为基体改进剂,选择灰化温度和原子化温度分别为750 ℃和1 100 ℃。镉的质量浓度在5 μg·L-1以内呈线性,方法的检出限(3s/k)为3.3 μg·kg-1。方法用于高钙食品样品分析,加标回收率在90.0%~103.3%之间,相对标准偏差(n=7)在2%~3%。

Sample of food with high calcium content was digested with HNO3 in a porcelain crucible by heating at low temperature, and evaporated to near dryness. The residue was taken up with HNO3 (1+99), and made up to 25 mL. Calcium in the sample solution was then determined by GF-AAS with Mg(NO3)2 added as matrix modifier. Temperatures of 750 ℃ and 1 100 ℃ were chosen for ashing and atomization respectively in the operation of graphite furnace. Linearity range of calcium was kept in the range within 5 μg·L-1 with detection limit (3s/k) of the method 3.3 μg·kg-1. The proposed method was applied to the analysis of samples of calcium supplementary food, and values of recovery obtained by standard addition method were in the range of 90.0%-103.3%. Values of RSD′s (n=7) found were ranged from 2% to 3%.