溶剂萃取耦合FTIR技术快速分析食用油中微量水分的研究

Establishment and Application of Solvent Extraction Coupled with FTIR Spectroscopy Method for Trace Water in Oil Analysis

研究应用溶剂萃取耦合傅里叶红外光谱（FTIR）技术建立快速分析食用油中微量水分的方法。数据显示乙腈是最佳萃取溶剂，其起始含水量〈300μg／g时对乙腈的萃取能力无明显影响。乙腈／油脂比例为1．5—2：1效果较佳，定量基于差谱的二阶导数明显优于差谱，对于萃取水分的乙腈渡谱中HOH弯曲振动1631cm^-1最优，灵敏度高于OH伸缩振动3630cm^-1和3541cm^-1。对所有测试样品，FTIR法的结果与标准卡尔费休法高度一致，并表现出优良的准确性和精确性（标准差-30，变异系数3％）。研究表明溶剂萃取耦合FTIR快速分析食用油中微量水分切实可行。

FTIR analysis of moisture in edible oils coupled with solvent extraction has been examined in the paper. The results suggested that acetonitrile was the optimal extraction solvent. On condition being less than 300 μg/g, initial moisture in acetonitrile had no significant effect on extraction capability. The acetonitrile to edible oil ratio of 1.5 - 2：1 was fit. When based on gap -segment 2nd derivative processed spectra, quantitative analysis could be more accuracy than that being based on differential spectra. It had a higher sensitivity in the 1 640 cm-1 as opposed to 3 630 cm-1 and 3 541 cm-1. On optimal conditions, the SD of calibration curve could be 3.3 μg/g. For all the tested samples, FrIR results could well match those determined by Karl Fisher method, and showed fine accuracy and precision （with a SD of 30 and relative standard deviation of 3% ）. It was proved that the analysis of moisture in edible oil by FTIR combined with solvent extraction was feasible.