Direct Analysis of Dimethicone in Aqueous Emulsions by Infrared Spectroscopy.

Dimethicone is a mixture of fully methylated linear siloxane polymers of various molecular weights. This water-insoluble ingredient provides exceptional skin protection and lubrication when incorporated into skin and hair care products. Quantitative analysis of dimethicone is often required to support quality assurance testing of finished products. We report a new, rapid analytical method based on Fourier transform infrared spectrometry, using a special attenuated total reflectance cell to determine concentrations of dimethicone directly in aqueous emulsions present in personal care products. This rapid, simplified method eliminates sample preparation to remove water, while providing reliable results across a wide range of dimethicone concentrations.

Rapid Analysis of Copper Ore in Pre-Smelter Head Flow Slurry by Portable X-ray Fluorescence.

Copper laden ore is often concentrated using flotation. Before the head flow slurry can be smelted, it is important to know the concentration of copper and contaminants. The concentration of copper and other elements fluctuate significantly in the head flow, often requiring modification of the concentrations in the slurry prior to smelting. A rapid, real-time analytical method is needed to support on-site optimization of the smelter feedstock. A portable, handheld X-ray fluorescence spectrometer was utilized to determine the copper concentration in a head flow suspension at the slurry origin. The method requires only seconds and is reliable for copper concentrations of 2.0-25%, typically encountered in such slurries.

HPLC analysis of selected xanthones in mangosteen fruit.

Xanthones are unique chemical compounds found in nature, composed of a tricyclic aromatic system with a variety of phenolic, methoxy, and isoprene substituents, giving rise to numerous derivatives. They dissolve to varying degrees in solvents ranging from alcohol to hexane. An optimum solvent mixture of acetone/water (80:20) selectively and effectively extracts a wide variety of xanthones. Subsequent HPLC analysis using standard C-18 RP and a 30-min gradient of 65-90% MetOH in 0.1% formic acid detects and separates numerous different xanthones with UV detection at 254 nm. The xanthones alpha-mangostin, 8-desoxygartanin, gartanin, beta-mangostin, 3-mangostin, and 9-hydroxycalabaxanthone have been extracted, identified, and quantitatively determined using this method. This analytical method is applied to the analysis of these xanthones in the rind of the mangosteen fruit, Garcinia mangostana.