硝酸浓度对火焰-原子吸收光谱法测定牛奶中钙含量的影响

Effect of Nitric Acid Concentration on Determination of Calcium in Milk by Flame Atomic Absorption Spectrometry

火焰-原子吸收光谱法是《GB 5009.92—2016食品安全国家标准食品中钙的测定》的第一法,本文通过试验确定硝酸浓度对火焰-原子吸收光谱法测定钙离子具有负干扰的作用。当硝酸浓度<2%时,该作用随着硝酸浓度增大而增大,当硝酸浓度≥2%时,相同钙离子浓度的空白校正信号强度基本不变,因此牛奶样品经过微波消解的前处理,通过调整待测样品的硝酸浓度≥2%,可以有效地消除硝酸浓度对钙离子测定的影响,提高检测结果的准确性,更科学地评价牛奶中钙的含量。

Flame atomic absorption spectrometry is the first method in GB 5009.92-2016 National food safety standard-determination of calcium in food.It is confirmed by experiment that the concentration of nitric acid has a negative interference effect on the determination of calcium.When the concentration of nitric acid is less than 2%,the effect increases with the increase of nitric acid concentration,on the contrary,the intensity of blank correction signal of the same calcium ion concentration basically unchanged.Therefore,the sample was pretreated by microwave digestion.The influence of nitric acid concentration on the determination of calcium ions can be effectively eliminated by adjusting the concentration of nitric acid of the samples to be measured≥2%.It can improve the accuracy of the test results and evaluate the calcium content in milk more scientifically.