Ionic substances with melting points at or close to room temperature are referred to as ionic liquids. Interest in ionic liquids for their potential in different chemical processes is increasing, because they are environmentally benign and are good solvents for a wide range of both organic and inorganic materials. In this study, a capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts is reported. The method, in which 1-alkyl-3-methylimidazolium-based ionic liquids are used as the running electrolytes, is simple and reproducible. The separation mechanism seems to involve association between the imidazolium cations and the polyphenols. The role of the alkyl substituents on the imidazolium cations was investigated and will be discussed.
Various Brassica species accumulate Se into the thousands of ppm. This suggests some of them as candidates for Se phytoremediation. Brassica juncea (Indian mustard) was used to accumulate selenium by growing with sodium selenite as the selenium source under hydroponic conditions resulting in Se accumulation of up to hundreds of ppm in various parts of the plant. To date, few selenium speciation studies have been done in plants, with most studies reporting total selenium concentration in various parts of the plant. Se species extraction was evaluated by several digestion/extraction procedures, including the use of HCl, Tris-HCl buffer, and enzymatic hydrolysis (using proteinase K and protease XIV). The best extraction was obtained with proteinase K (extracting approximately 75% of the total Se present in the plant). Some of the species produced by the plant, such as selenomethionine, can be identified at ppb levels by RP-HPLC-ICPMS, since standards are readily available. Others needed to be further characterized by ES-MS. Enzymatic hydrolysis releases mostly Se-methionine from juncea leaves, although other Se-containing species can also be observed by HPLC-ICPMS. In this initial study, the possible identification (by ES-MS) of a small chromatographic peak containing a Se-S bridged seleno amino acid with a structure similar to cystine is suggested.
A capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts was developed using a quaternary ammonium salt as the main electrolyte solution. Seven polyphenols were separated and identified. The separation mechanism seems to involve association between quaternary ammonium cations and the polyphenols. Migration times roughly correlate with the size of the known phenols. The role of the alkyl substituents on the quaternary ammonium ions was investigated and is discussed. The method of analysis proposed herein exhibits high reproducibility in terms of migration times for a complex mixture using a single component background electrolyte.
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