中红外光谱法快速测定牛奶中非蛋白氮类物质

Fast determination of nonprotein nitrogen content in milk based on mid-infrared spectroscopy method

建立了一种用红外光谱法检测牛乳中掺有非蛋白氮类物质的方法。往牛奶中添加不同含量的尿素和三聚氰胺,通过扣除水背景和牛奶背景等不同方法,利用Nicolet 6700傅立叶变换红外光谱仪获取非蛋白氮类物质的光谱,找出掺假物质的特征峰。将不同MATLAB程序分别同掺假物质特征峰的波数和特征峰的吸光度值或峰面积相结合,可以对牛乳中是否掺有非蛋白氮类物质进行定性和定量分析,其判别正确率为95.49%,相对误差在2%以内。该方法快速、简便易行,适用于多种非蛋白类掺假物质的检测。

A method for detection of adulteration in milk containing nonprotein nitrogen by infrared spectroscopy was established. Through adulterating different content of urea and melamine into pure milk,the infrared spectral data of the samples were obtained by the Nicolet 6700 FT-IR Spectrometer,followed by water background correction and milk background correction to carry on processing the spectrum data,the characteristic peaks of urea and melamine were obtained. Combining the different MATLAB program with the wavenumber,the absorbance value or the peak area of characteristic peaks,the adulterants in milk could be judged. The method could be used for quantitative and qualitative analysis of adulterants. The correct recognition rate was95.49%,the relative error was within 2%. This method was fast,simple and suitable for determination of different nonprotein nitrogen.