Fourier Transform Infrared (FTIR) Spectroscopy as a Utilitarian Tool for the Routine Determination of Acidity in Ester-Based Oils.
Fourier Transform Infrared (FTIR) Spectroscopy as a Utilitarian Tool for the Routine Determination of Acidity in Ester-Based Oils.
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DOI：
10.1021/acs.jafc.5b02738
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发表时间：
2015-09
影响因子：
6.1
通讯作者：
Xianghe Meng;Lei Li;Qin Ye;F. R. van de Voort
中科院分区：
文献类型：
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作者：
Xianghe Meng;Lei Li;Qin Ye;F. R. van de Voort
介绍并评价了一种一次傅立叶变换红外光谱(FTIR)测定酯基油脂酸度的方法。在精制的无酸油中添加油酸，并在二阶导数差示光谱中分别测量ν1569处的∼COO(-)和∼1588 cm(-1)处的ν酚值(-)，从而设计了绝对游离脂肪酸(%FFA)和酸值(AV)的校正方法。FTIR酸度预测与AOCS滴定方法进行了比较，使用的是混合酸以及含有酸的成分和来源不明的二手供应商油，使用了两种光谱差异较大的参照油作为AC0。相对于AOCs参考法，FTIR法在测定%FFA方面更准确(±0.107比±0.122)，重复性(±0.025比±0.077)，在预测房颤方面相似。FTIR酚化法克服了早期基于FTIR的方法的各种限制，特别简单，非常适合使用基本FTIR光谱仪进行常规、半自动的酯基油酸度分析。
A primary Fourier transform infrared (FTIR) method capable of determining acidity in ester-based oils is described and evaluated. Absolute free fatty acid (%FFA) and acid value (AV) calibrations were devised by spiking oleic acid into a refined, acid-free oil and measuring ν COO(-) at ∼ 1569 and ν phenolate(-) at ∼ 1588 cm(-1), respectively, in the second-derivative differential spectra. The FTIR acidity predictions were compared to the AOCS titrimetric method using acid mixtures as well as acid containing used vendor oils of undefined makeup and provenance, using two spectroscopically divergent reference oils as AC0. Relative to the AOCS reference method, the FTIR procedure was found to be both more accurate (± 0.107 vs ± 0.122) and reproducible (± 0.025 vs ± 0.077) in determining %FFA and similar in predicting AV. The FTIR phenolate method overcomes a variety of limitations of earlier FTIR-based methods, being particularly simple and well suited to routine, semiautomated acidity analysis of ester-based oils using a basic FTIR spectrometer.