采用火焰原子吸收光谱法测定了乳酸菌发酵虾壳液中钙量。钙的质量浓度在24.0 mg·L-1范围以内与对应的吸光度呈线性关系,检出限(3s)为0.065 mg·L-1。在含钙10.67 mg·L-1试样溶液中加入10.00 mg·L-1钙标准溶液后按试验方法测定,根据测定值算得平均回收率为101.2%。为考查方法的精密度,对含钙1.33%(质量分数,下同)的样品作重复测定,求得测定值的相对标准偏差(n=6)为0.37%,并用EDTA滴定法对同一样品中钙量进行对比测定,测得其平均值(1.39%)与已知值基本相符。EDTA滴定法测定值的相对标准偏差(n=6)为0.59%。还证明了样品中存在的有机物对火焰原子吸收光谱法测定钙未造成干扰。

FAAS was applied to the determination of calcium in lactobacilli-fermentation liquor of shrimp shell. Linear relationship between values of absorbance and mass concentration of Ca2+ was obtained in the range within 24.0 mg·L-1. Detection limit (3s) found was 0.065 mg·L-1. Recovery was tested by addition of standard calcium solution (10.00 mg·L-1) to fermentation liquor samples (containing 10.67 mg·L-1 of Ca2+), value of average recovery found was 101.2%. Precision was tested by replicate determination of Ca2+ in a substantial sample (wCa 1.33%) by the present method, value of RSD (n=6) found was 0.37%. Average results of (w) 1.39% in consistency with the known value, was obtained by the EDTA titrimetric method with value of RSD (n=6) 0.59%. It was proved that the presence of organic substances in the sample solution did not show any interference to the determination of Ca2+ by the present method.