Mass spectral evaluation of column bleeding for imidazolium-based ionic liquids as GC liquid phases.

Mass spectra were obtained to evaluate the use of numerous single-cation and dicationic ionic liquids as stationary liquid phases in GC/MS at high temperature. Background mass spectra and product ion mass spectra of several ions in the background spectrum were obtained. Fragmentation mechanisms were propounded, including the detailed fragmentation pathway of the 1,2-dimethyl-3-propylimidazole cation. The relation between temperature and the main signals in the mass spectra of ILs was studied.

Screening and comparative metabolic profiling of high lipid content microalgae strains for application in wastewater treatment.

New strains of green microalgae were isolated and screened for growth and the production of lipids from municipal wastewater. It was shown that the strain Micractinium sp. IC-76 has a biomass productivity of 37.18 ±â€¯4.12 mg L-1 d-1 and a lipid content of 36.29 ±â€¯0.11%, with a total content of saturated and monounsaturated fatty acids of 71.9%. The efficiency of nitrogen (N-NH4) and phosphorus (P-PO4) removal was 96.4 ±â€¯0.7 and 77.8 ±â€¯5.6%, respectively. The metabolic differences at the exponential and stationary phases of growth between the closely related strains with different patterns of lipid accumulation were revealed via gas chromatography mass spectrometry metabolic profiling. The strain Micractinium sp. IC-76 in the stationary phase of growth shows a significant difference in carbohydrate metabolism, especially sucrose concentration. High lipid induction during cultivation in wastewater was also driven by changes in the biosynthesis of amino acids, fatty acids and the tricarboxylic acid cycle.

Properties of columns with several pyridinium and imidazolium ionic liquid stationary phases.

Recent advances in the development of new liquid phases (ILs) made it possible to use some classes of ILs as polar stationary liquid phases (SLP). In our days only alkylimidazolium- and alkylphosphonium-based ILs are widely used as polar SLP. In present work some other types of ILs - pyridinium and cyanopropyl/hydroxypropyl imidazolium were investigated as SLP. Columns with efficiencies 2000-2500 plates/m by high-pressure static method were prepared. Polarity and selectivity of these phases were measured. Selectivity was described in terms of intermolecular interactions by using Abraham solvatation parameter model. The set of the regularities between cation structure of ionic liquid and selectivity has been shown. The number and position of methyl groups in ionic liquid pyridinium ring were shown to have the sufficient influence on all type of molecular interactions. Finally the resolutions of test mixture for the several ionic liquid SLP were obtained. For columns with some ionic liquids the dependencies of the height equivalent to a theoretical plate (HETP) and sample loading capacity were obtained and compared with the conventional phases. It was found that the optimal efficiency for the IL columns is attained at lower carrier gas velocities in comparison with traditional phases. Nevetheless sample loading capacity of IL phases is comparable to those of conventional GC phases.