FTIR技术结合区间偏最小二乘法快速测定油脂中反式脂肪酸

Rapid Determination of Trans-Fatty Acids in Oils and Fats by FTIR Technology Combined with Interval Partial Least Squares

研究了傅里叶红外光谱技术结合区间偏最小二乘法(iPLS)快速分析食用油中低含量(0.1%~5%)反式脂肪酸的分析方法。通过系统地比较衰减全反射红外光谱法(ATR-FTIF)及衰减透射红外光谱法(TR-FTIR)光谱的模型效果,优化建模区间。研究结果表明,ATR-FTIR、TR-FTIR-PLS回归模型均能有效测定油脂中低浓度反式脂肪酸的含量,但TR-FTIR法灵敏度优于ATR-FTIR法。iPLS区间选择结果显示,以1 000~940 cm^(-1)波段透射光谱建模,相关系数R^2为0.998 8,标准集的RMSEC 0.016 6,验证集RMSEP为0.008 75,预测相对标准偏差2.92%,预测值与实际值高度相关,Y_(预测)=1.00X_(实际)-0.003 44,R^2=0.998 7。12组外部验证试验相对标准偏差为4.80%,说明预测精确度较高、模型稳定性好,有潜力替代传统气相色谱法用于油脂中低含量反式脂肪酸快速定量测定。

In order to rapidly analyze the low level （0.1% - 5 % ） trans fatty acids in edible oils, FTIR technology combined with interval partial least squares is studied in this paper. The effects of attenuated total reflection - Fourier transform infrared spectroscopy （ ATR - FTIR） and Fourier transform infrared spectroscopy （ TR - FTIR ） models are systematically compared for optimization of spectral modeling interval. The results show that both ATR - FTIR regression model and TR - FTIR - iPLS regression model are effective in term of determination of low level trans fatty acids in oils. However, TR - FTIR method has higher sensitivity than that of ATR - FTIR method. The results of iPLS interval selection demonstrate that when transmission spectra model is established based on 1 000 -940 -1 cm , coefficient of correlation R2 （0. 998 8 ）, RMSEC of O. 016 6, RMSEP of 0.008 75 and relative standard devia- tion of 2.92% are obtained. The FFIR/TR predictive values are highly correlated with the actual values with a regression equation of Yprediction = 1.00Xactuality - 0. 003 44, R2 = 0.998 7. The relative standard deviation of 12 groups of external validation tests （4.80%） shows that the model has higher prediction accuracy, and better stability. It is potential for TR/FTIR - iPLS method to be taken as an alternative to the traditional gas chromatography for rapid determination of low concentration of trans fatty acids in oils.