Value assignment and uncertainty evaluation for anion and single-element reference solutions incorporating historical information.

The National Institute of Standards and Technology, which is the national metrology institute of the USA, assigns certified values to the mass fractions of individual elements in single-element solutions, and to the mass fractions of anions in anion solutions, based on gravimetric preparations and instrumental methods of analysis. The instrumental method currently is high-performance inductively coupled plasma optical emission spectroscopy for the single-element solutions, and ion chromatography for the anion solutions. The uncertainty associated with each certified value comprises method-specific components, a component reflecting potential long-term instability that may affect the certified mass fraction during the useful lifetime of the solutions, and a component from between-method differences.

Determination of Iodine Value in Hydrogenated Oils: Comparison of Titration and Gas Chromatography with Flame-Ionization Detection Methodologies.

The United States Food and Drug Administration (FDA) recently issued its final determination that partially hydrogenated oils (PHO) are no longer generally recognized as safe (GRAS) for any use in human food. Consequently, the discrimination between PHO and fully hydrogenated oils (FHO), which is achieved by the iodine value (IV), has become an important regulatory issue. This study compared American Oil Chemists' Society (AOCS) and International Organization for Standardization (ISO) titration and gas chromatography with flame-ionization detection (GC-FID) methodologies for the determination of IV in seven samples of hydrogenated oil, namely coconut, cottonseed (n = 2), palm kernel, palm stearine, and soybean (n = 2) oils.