Edible oil analysis by FTIR spectroscopy
ABSTRACT Fourier-transform infrared (FTIR) spectroscopy offers a new way of approaching edible oil analysis and is well on its way to being developed into a utilitarian quality control tool. This paper provides a brief overview of FTIR spectroscopy, the key elements associated with developing a suitable fats and oils analytical system (sample handling, calibration development, validation, calibration stability and transfer, programming and automation), some methods that have been implemented, and the basic elements of a typical fats and oils FTIR analytical package. It is foreseen that a number of standard AOCS methods will be replaced by this technology, allowing a variety of chemical and physical analyses to be carried out on neat fats and oils in under 2 minutes per sample. © 1996 John Wiley & Sons, Inc.
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ABSTRACT: A method for the simultaneous determination of iodine value (IV) and trans content from the Fourier transform infrared (FTIR) spectra of neat fats and oils recorded with the use of a heated single-bounce horizontal attenuated total reflectance (SB-HATR) sampling accessory was developed. Partial least squares (PLS) regression was employed for the development of the calibration models, and a set of nine pure triacylglycerols served as the calibration standards. Regression of the FTIR/PLS-predicted IV and trans contents for ten partially hydrogenated oil samples against reference values obtained by gas chromatography yielded slopes close to unity and SD of <1. Good agreement (SD<0.35) also was obtained between the trans predictions from the PLS calibration model and trans determinations performed by the recently adopted AOCS FTIR/SBHART method for the determination of isolated trans isomers in fats and oils.Journal of Oil & Fat Industries 03/2000; 77(4):399-403. · 1.59 Impact Factor
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ABSTRACT: Introduction The quality or status of a lubricant is directly related to the performance and reliability of machinery and the importance of condition monitoring so as to avoid excessive wear and downtime of equipment and critical components has been recognized (1). The chemical and physical parameters analyzed for are largely based on standardized analytical methods to provide an overall indication of the status of a lubricant. However, key ASTM chemical methods such as the determination of Total Acid Number (TAN), Total Base Number (TBN) and moisture (H 2 O) are troublesome to carry out, being tedious, time consuming and trouble prone even in their automated forms. Today, there is more emphasis on structured condition monitoring to provide trending data so that one can take preventive action on the one hand, but not take unnecessary action on the other. This approach may extend drain intervals and reduce lubricant disposal and maintenance and failure costs. On the other hand, extensive testing is required and data management can become complex. FTIR Spectroscopy In this context, an instrument that has become increasingly prominent in lubricant analysis is the infrared spectrometer, specifically the Fourier transform infrared (FTIR) spectrometer. This analytical instrument effectively provides a spectral snapshot of the base oil and other constituents present. Its power is based on the fact that specific molecular functional groups absorb in unique regions of the mid-infrared spectrum, allowing identification of additives, contaminants and breakdown products. Although IR spectral information is meaningful to a spectroscopist, its meaning is not necessarily apparent to the non-expert. Even with this limitation, IR spectroscopy is still a very powerful tool, simply because it can provide substantial information about oil condition using a single instrument. Indications about the state of oxidation, nitration and sulfation and levels of soot, moisture, glycol and various additives, among others, is available. Extensive IR studies of lubricants and fuels have led to the establishment of standardized protocols to monitor selected condition parameters under the guise of the Joint Oil Analysis Program (JOAP). These protocols, and similar protocols under consideration by the ASTM, provide a comprehensive means of monitoring the condition of lubricants using a single analytical technique.
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ABSTRACT: A Fourier transform infrared (FTIR) spectrometer equipped with an attenuated total reflectance (ATR) sample handling accessory was used to rapidly monitor the peroxide value (PV) of oils undergoing catalytic oxidation to produce sulfonated fatliquors used in the leather industry. PV quantitation was based on the stoichiometric reaction of triphenylphosphosphine (TPP) with hydroperoxides to produce triphenylphosphine oxide (TPPO). By using a germanium ATR accessory that has a very short effective pathlength, the spectral contributions of the base oil could be subtracted out, eliminating any oil-dependent intereferences as well as providing a facile means of observing the spectral changes associated with the TPP/TPPO reaction. A calibration was devised by adding a constant amount of TPP-saturated chloroform to oils containing varying amounts of tert-butyl hydroperoxide (TBHP) to produce TPPO that had a measurable band at 1118 cm−1. this band was linearly related to TBHP concentration and the calibration devised had an SD of ∼3.4 PV over the range of 0–250 PV. The ATR-PV method was standardized and the spectrometer programmed using Visual Basic to automate the analysis. the automated FTIR-ATR method was found to be a convenient means of tracking PV of oils undergoing oxidation, and the results correlated well with the PV values obtained using the AOAC iodometric method (r=0.94). The FTIR-ATR PV methodology provides a simple means of monitoring the PV of oils undergoing rapid oxidation and could serve as a quality-control tool in the production of sulfonated oils for the leather industry.Journal of Oil & Fat Industries 01/2000; 77(6):681-685. · 1.59 Impact Factor