University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
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Journal of the American Oil Chemists Society

  • Publisher: Springer
  • FAD Code: JAOC
  • CODEN: JAOCA7
  • ISSN: 0003-021X
  • Abbreviation: J. Am. Oil Chem. Soc.
  • DOI Prefix: 10.1007/s11746,10.1007/BF
  • Language: English
  • Comments: Fulltext from 1927 V4

Citations 6

"Development Of A Flow Injection Chemiluminescent Assay For The Quantification Of Lipid Hydroperoxides"
J. Am. Oil Chem. Soc. 2003 Volume 80, Issue 10 Pages 951-955
John P. Bunting and David A. Gray

Abstract: An automated flow injection chemiluminescence (FICL) system for measuring lipid hydroperoxide (LOOM) concentrations in oils was developed. Initially, a crude oil-in-water emulsion (formed by mixing solvent-diluted oil with the aqueous-based CL compound, luminol, and the catalyst for the reaction, cytochrome c) was tested. The assay was rapid (60 samples per hour), reproducible (CV no greater than 10%, n = 3) and had a low sample requirement (1 mg of oil) because of its high sensitivity (0.5 nmol LOOH). CL intensity was influenced by the amount and type of oil under analysis. Owing to these factors, quantitative data were attainable only with a uniform oil concentration and with a calibrant derived from an oil equivalent to that under analysis. This method yielded quantitative data in good agreement with an iodometric titration assay for LOOH (r = 0.9204). A refinement of the first method consisted of replacing the luminol and cytochrome c CL compounds with lucigenin, resulting in an assay insensitive to ?-tocopherol. A monophasic reaction solution was devised to remove the effect of turbidity; however, the CL signal was still influenced by oil type. Therefore, quantitative data were still attainable only when the same type of oil was used for calibration.

"Synthetic Antioxidants In Edible Oils By Square-wave Voltammetry On Ultramicroelectrodes"
J. Am. Oil Chem. Soc. 2000 Volume 77, Issue 7 Pages 731-735
Hector Fernández

Abstract: Square wave voltammetry (SWV) on carbon disk ultramicroelectrodes (UME) was used to determine antioxidants terf-butylhydroxyanisole (BHA) and tert-butylhydroxytoluene (BHT) in vegetable oils. Direct determinations were accomplished in benzene/ethanol/H2SO4 solutions or in acetonitrile (ACN) after an extractive procedure. Much better recovery percentages were obtained in ACN extracts. By comparing with high-performance liquid chromatography (HPLC) results, BHA has a slightly lower recovery percentage by the SWV technique on ACN extracts. On the other hand, BHT shows a greater recovery percentage using the methodology proposed here. The analysis time through SWV is less than an hour for a duplicated analysis while the HPLC technique needs a greater time, besides the overnight stored time required by the current methodology. The present work tends to show that SWV on carbon disk UME allows sensitive, reproducible, and faster determination of BHA, BHT, or antioxidant mixtures in oil-solvent solutions or after a simple extractive procedure with the advantage of a higher recovery percentage. This validates the methodology as an analytical alternative for antioxidant quantification.

"Determination Of Oxidative Stability Of Lipids In Solid Samples"
J. Am. Oil Chem. Soc. 2000 Volume 77, Issue 3 Pages 217-222
Kang Tian* and William D. Shermer

Abstract: A gas-phase flow injection analysis (FIA) method for the direct determination of the oxidative stability of solid fat/oil samples is described. Samples are confined with a low level of oxygen in a reactor of adjustable temperature. The oxygen consumption by the sample is automatically monitored after a preset period. The temperature-dependent data exhibit Arrhenius behavior. Normally, it is difficult to directly determine the stability at ambient temperatures because of inordinately long time requirements. The close correspondence to Arrhenius behavior makes it possible to use the results obtained at higher temperature to calculate the stability of samples at lower temperature conditions, such as at ambient storage temperature. The effects of sample size, sample particle size, sample fat content and the reproducibility of the method over time were studied using synthetic and bone meal samples. The oxygen consumption was found to be linearly dependent on the amount of sample taken, inversely dependent on the particle diameter, and independent of the exact lipid content, given some minimum lipid content. The results exhibited high day-to-day reproducibility. The gas-phase FIA system developed in this work is easy to operate. Compared with the currently used method, the sample throughput rate is much faster (2-3 h for complete multitemperature characterization of a sample) and the sample requirement is much lower (~1 g). Furthermore, it eliminates the need to extract and recover the fat from the sample for further processing as is required by the other methods commonly used to measure oxidative stability.

"A Simple And Cost-effective Gram-scale Chromatographic Method For The Purification Of Soybean Phospholipids"
J. Am. Oil Chem. Soc. 1995 Volume 72, Issue 9 Pages 1073-1075
B. De Meulenaer, P. Van der Meeren, J. Vanderdeelen, L. Baert

Abstract: A method was developed for the preparative fractionation of soybean lecithin to enable the study of the functional properties of pure soybean phospholipids. Hereby, a coarse and irregularly shaped silica gel was used as the stationary phase, whereas the mobile phase consisted of three mixtures of hexane, 2-propanol, and water with increasing polarity. These solvents were included in a step gradient, which was formed by an isocratic pump connected to a solvent switcher. With this system, two grams of soybean lecithin were fractionated. The purity was evaluated by analytical high performance liquid chromatography, and the recovery was estimated from concentration determinations by flow injection analysis. From these results, it was concluded that 60 to 75 of the three major soybean phospholipids could be recovered with a purity of at least 93. Only 1.5 L of solvents were needed for both the column equilibration and the elution of all soybean phospholipids. Reprinted by permission of the publisher.
Lecithin Vegetable HPLC

"Automated Free Fatty Acid Determination Using Flow Injection Analysis Solvent Extractions"
J. Am. Oil Chem. Soc. 1987 Volume 64, Issue 7 Pages 1004-1007
John S. Canham and Gilbert E. Pacey

Abstract: The sample (100 µL) was injected into the carrier (toluene) stream which then segmented with the reagent (Cu(II) - pyridine) stream and passed (1.4 mL min-1) through a coil of PTFE tubing (0.5 m x 0.5 mm). The stream then entered the membrane separator (3.5 cm x 0.2 cm) and the absorbance of the toluene phase, containing the Cu(II) - fatty acid complex, was measured at 699 nm. The calibration graph was rectilinear in the range 60 µM to 6 mM oleic acid. Precision was ~1%. Solvent-extraction flow injection analysis (flow diagram presented) improved the rate of sampling, sensitivity and precision, and reduced the amount of reagent used and the hazards from toxic fumes.
Fatty acids, free Feed Spectrophotometry Sample preparation Optimization Phase separator Solvent extraction Teflon membrane

"Automated Method For Determination Of Free Fatty Acids"
J. Am. Oil Chem. Soc. 1981 Volume 58, Issue 10 Pages 935-938
Lars-Gösta Ekström

Abstract: An automated colorimetric method is described for determining free fatty acids (FFA) in vegetable oils using the flow injection analysis (FIA) technique. In this procedure, an almost linear relationship exists between the peak height and the FFA concentration. Liquid samples can be poured directly into the sample cups on the sampler for an automatic analysis of the FFA content. The dynamic range of this method is from 0.01 to almost 5%. Samples with higher FFA content must be diluted before analysis. The sample capacity is 12-20 injections/hr. No evidence of the existence of the earlier proposed cage-like complex (Cu(II)(FFA)2)2 in the organic phase was observed in this study.
Fatty acids, free Oil Spectrophotometry Sample preparation Automation Extraction