奶粉中钙含量的非线性化学指纹图谱法测定

Determination of Calcium Content in Milk Powder Based on Nonlinear Chemical Fingerprint Method

采用非线性化学指纹图谱法对奶粉中固有钙含量进行定量分析。先用国标火焰原子吸收分光光度法对3份奶粉标准样品中固有的钙含量进行测定,分别向奶粉标样中加入不同量的碳酸钙,利用＂硫酸-硫酸锰-丙酮-溴酸钠-标样成分＂为反应体系,通过非线性化学指纹图谱法对含有不同量碳酸钙的奶粉进行测定,运用最小二乘法,拟合出其波动周期与奶粉中钙的总含量之间的一元线性关系,当奶粉中钙的加入量已知时,可求出奶粉中固有的钙含量。实验表明,当奶粉总量为0.9 g、奶粉中钙的总含量在0.022 7-0.032 3 g范围内时,钙的总含量与波动周期线性关系良好,决定系数R2为0.995 3-0.998 8,样品加标回收率为99.18%-101.60%,RSD为0.47%-1.63%,奶粉中固有的钙含量检测范围为0-0.032 3 g。方法准确度高,操作简单,是一种切实可行的测定奶粉中固有钙含量的方法,也可作为复杂样本中其它成分定量分析借鉴的方法。

The inherent content of calcium in milk powder was rapidly determined by using the nonlinear chemical fingerprint method. Firstly,the inherent calcium content in three brands of milk powder was determined by using flame atomic absorption spectrometry as described by GB 5413. 21—2010（ National Standards of PR China）. Different contents of calcium carbonate were added into the above three brands of milk powder,respectively. Using＂H^＋＋ Mn^2 ＋＋ Br O3^-＋ acetone ＋ substrates in milk powder ＂as reaction system,the nonlinear chemical fingerprints of milk powder with different calcium contents were obtained,and there was a linear relationship between the undulatory period and the total content of calcium in milk powder,where the total content of calcium consisted of the inherent calcium content in milk powder and the calcium content of being added into milk powder. Then,the inherent content of calcium in milk powder was calculated by using the least square method. The results showed that the total content of calcium in milk powder and the undulatory period value had a good linear relationship within0. 022 7 - 0. 032 3 g range of the total content of calcium when the total amount of milk powder was0. 9 g,the determination coefficient was 0. 995 3 - 0. 998 8,the recovery rate was 99. 18% - 101. 60%,the RSD was 0. 47% - 1. 63%,and the determination range of the inherent calcium content in milkpowder was 0 - 0. 032 3 g. The method developed has advantages of good accuracy and simple operation,and it is a practical and feasible method for determining the inherent calcium content in milk powder. In addition,the method can be used for reference in research on the methods for the determination of other components in other complex samples.