Phenolic composition of pomegranate peel extracts using an liquid chromatography-mass spectrometry approach with silica hydride columns.

The peels of different pomegranate cultivars (Molla Nepes, Parfianka, Purple Heart, Wonderful and Vkunsyi) were compared in terms of phenolic composition and total phenolics. Analyses were performed on two silica hydride based stationary phases: phenyl and undecanoic acid columns. Quantitation was accomplished by developing a liquid chromatography with mass spectrometry approach for separating different phenolic analytes, initially in the form of reference standards and then with pomegranate extracts. The high-performance liquid chromatography columns used in the separations had the ability to retain a wide polarity range of phenolic analytes, as well as offering beneficial secondary selectivity mechanisms for resolving the isobaric compounds, catechin and epicatechin. The Vkunsyi peel extract had the highest concentration of phenolics (as determined by liquid chromatography with mass spectrometry) and was the only cultivar to contain the important compound punicalagin. The liquid chromatography with mass spectrometry data were compared to the standard total phenolics content as determined by using the Folin-Ciocalteu assay.

The separation and analysis of symmetric and asymmetric dimethylarginine and other hydrophilic isobaric compounds using aqueous normal phase chromatography.

Two biologically important compounds with clinical relevance, asymmetric dimethylarginine and symmetric dimethylarginine, are analyzed using aqueous normal phase chromatography on silica hydride-based columns. Two different stationary phases were tested, a commercially available Diamond Hydride™ and a 2-acrylamido-2-methylpropane sulfonic acid experimental column. Two types of analytical protocols were investigated: analysis of the compounds when separation was achieved and analysis of the compounds with partial chromatographic separation. Urine samples from tuberculosis patients were tested for levels of asymmetric and symmetric dimethylarginine. The mass spectrometric technique of in-source fragmentation that can provide data similar to a tandem mass analyzer was evaluated as a means of identification and quantitation of the two compounds when complete separation is not achieved. This same protocol was also evaluated for two other isobaric compounds, glucose-1 and glucose-6 phohsphate, and leucine and isoleucine.