用近红外分析法测定绿茶的总氮量

通过对40个绿茶样品进行近红外光扫描和多元回归分析处理,求得总氮的近红外特征吸收波长为2088毫微米,计算绿茶的总氮量的多元回归方程式为 C_((T-N%))=3.302+1.721d~2OD(2088毫微米/1684毫微米)+0.905d~2OD(2042毫微米/2046毫微米),标准偏差 S=0.0723,相关系数 r=0.9964。径用27个茶样验证,r=0.993,S=0.0808,并经 t 检验,近红外法和化学法测定结果差异不显著。因此,确认近红外测定绿茶的总氮量的分析方法,可以用于绿茶的品质检

Near Infrared (NIR) Spectrophotometric Analysis of Total Nitrogen Content in Green Tea

Forty green tea samples were scanned by NIR light.A stepwise multiplelinear regression analysis of the second derivative spectra of green tea selectedfour wavelengthes in the order of 2088,1684,2042 and 2046.The calibrationequation is as follows:C(T-N%)=3.302+1.721d_2OD(2088nm/1684nm)+0.905d_2OD(2042nm/2046nm).The standard deviation of difference(s)is0.0723,and the correlation coefficient(r)is 0.9964.The above equation wasverified with 27 green tea samples.The high relationship between the totalnitrogen contents from chemical analysis and NIR analysis was obtained,andthe correlation coefficient and the standard deviation of difference are 0.993and 0.0808 respectively.T test showed that the difference between the dataobtained from NIR and chemical method was not obvious.It is concludedthat NIR method can be used to analyze the total nitrogen content in greentea.