In 2006, the US FDA mandated the declaration of the total trans fat content on the Nutrition Fact label of foods including dietary supplements when a product contained 0.5 or more grams of trans fatty acid per serving; the minimum corresponding trans fat content is estimated to be approximately 2% of total fat. The FDA definition is based on chemical structure and includes only fatty acids with one or more isolated double bonds in the trans configuration. Several issues negatively impacted the sensitivity of the current official infrared (IR) methods, thus limited the quantitation of trans fat to 5% of total fat. To improve sensitivity and accuracy and to meet the labeling requirement, a new internal reflection IR procedure called negative second derivative is described and evaluated for the quantitation of total trans fat in the present study. The enhanced spectral features of a second derivative resolved issues that traditionally limited the sensitivity of the IR methodology. Calibration standard mixtures starting at approximately 0.5% trielaidin in the total fat (tripalmitin or triarachidin) were successfully generated and used to determine the trans fat levels for unknown test samples with trans content as low as approximately 1% of total fat. Quantitative IR data were compared to those obtained by gas chromatography and were found to be in good agreement.
In major applications, optimal power will be achieved when thermoelectric films are at least 100 lm thick. In this paper we demonstrate that screenprinting is an ideal method to deposit around 100 lm of (Bi,Sb) 2 (Te,Se) 3 -based films on a rigid or flexible substrate with high Seebeck coefficient value (90 lV K À1 to 160 lV K À1 ) using a low-temperature process. Conductive films have been obtained after laser annealing and led to acceptable thermoelectric performance with a power factor of 0.06 lW K À2 cm À1 . While these initial material properties are not at the level of bulk materials, the complete manufacturing process is cost-effective, compatible with large surfaces, and affords a mass-production technique.
Using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, collaborating scientists in ten different laboratories measured (in duplicate) the total trans fat content of ten fat or oil test samples, two of which were blind duplicates. The procedure used entailed measuring the height of the negative second derivative of the IR absorption band at 966 cm -1 . This absorption is attributed to the C-H deformation vibration that is characteristic of isolated (non-conjugated) double bonds with the trans configuration. The precision of ATR-FTIR results in this international collaborative study was satisfactory and led to the approval of this validated procedure as official method AOCS Cd 14e-09 in late 2009. This official method is also suitable for analysis of total isolated trans fat and oil products containing, or supplemented with, trans conjugated linoleic acid (CLA) isomers. Although this method does not require derivatization of the oil or fat test materials, as required for GC, fats and oils in foods must be extracted with organic solvents before analysis. This method is also rapid (5 min) and does not require any weighing or quantitative dilution of unknown neat fat or oil test samples in any solvent. The AOCS Cd 14e-09 method is suitable for determination of test samples with zero trans fat, which is defined according to the US labeling regulations as 0.5 g trans fat per serving or 1.8% trans fat, as a percentage of total fat.
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