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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24.0mg·L~(-1)范围以内与对应的吸光度呈线性关系,检出限(3s)为0.065mg·L~(-1)。在含钙10.67mg·L~(-1)试样溶液中加入10.00mg·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。
Flame atomic absorption spectrometry was used to determine the amount of calcium in the fermented shrimp shell liquid of lactic acid bacteria. The concentration of calcium in the range of 24.0mg · L ~ (-1) was linear with the corresponding absorbance, the detection limit (3s) was 0.065mg · L -1. Calcium 10.67mg · L -1 sample solution by adding 10.00mg · L -1 standard solution of calcium by the test method to determine the measured value calculated average recovery of 101.2%. In order to examine the precision of the method, the relative standard deviation (n = 6) of the measured value of 1.33% (mass fraction, the same below) was repeatedly measured and found to be 0.37% Comparison of calcium measurements, the measured average (1.39%) and the known value is basically consistent. The relative standard deviation (n = 6) of EDTA titration was 0.59%. It was also demonstrated that the presence of organic matter in the sample did not interfere with the determination of calcium by flame atomic absorption spectrometry.