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A. Podjava, P. Mekšs and A. Zicmanis

Liquid Chromatography - Mass Spectrometry of Zwitterionic Liquids

We have implemented full mass spectrometric assay of several 3-(1-alkyl-2-methylimidazolio)propanesulfonates, which are known as zwitterionic liquids (ZILs). Hydrophilic interaction liquid chromatography (HILIC) column and different mobile phases in both isocratic and gradient elution conditions were used for separation of the compounds present in these samples. The structures of the impurities have been confirmed by LC-MS/MS experiments. In addition, fragmentation pathways of ZILs were studied for different collision energies (0-50 eV) in positive electrospray ionization (ESI) mode under collision-induced dissociation conditions. Several new routes of fragmentation are briefly discussed. These include possible rearrangements and imidazolium ring expansions, which hypothetically proceed through carbocationic intermediates in the gas phase. Currently these processes are studied in a more detailed fashion.

Open access

O. Rotkaja, J. Golushko and P. Mekss

Abstract

Protein molecules present more complex analytical challenges than conventional low molecular weight pharmaceutical compounds, and thus need powerful analytical approaches for the entire pharmaceutical development and quality control process. We used high-performance liquid chromatography to investigate the reversed-phase chromatographic behavior of eleven proteins (albumin, carbonic anhydrase, cytohrome c, L-glutamic dehydrogenase, enolase, α-lactoglobulin, Lysozyme, myoglobin and ribonuclease. By using a water/organic solvent/trifluoroacetic acid system the influence of experimental parameters was examined, and chromatographic results from two C4- chain-length supports were found to be comparable. The model enables prediction of initial conditions from two experimental data points for different types of reversed-phase columns with water-acetonitrile-TFA, water-methanol-TFA, and water-2-propanol-TFA mobile phases

Open access

A. Zicmanis, S. Pavlovica, E. Gzibovska, P. Mekss and M. Klavins

2-Hydroxyethylammonium Carboxylates - Highly Biodegradable and Slightly Toxic Ionic Liquids

Highly hydrophilic ionic liquids easily form in reactions between 2-hydroxyethyl amines and carboxylic acids. They have low toxicity and high biodegradability, serve both as reaction solvents and catalysts in condensation reactions, and they may be reused several times without any purification.

Open access

S. Pavlovica, E. Gzibovska, A. Zicmanis, P. Mekss and M. Klavins

Hydrophilic Ionic Liquids in the Synthesis of Hantzsch Ester

Hantzsch ester synthesis was investigated using (2-hydroxyethyl)-ammonium carboxylates, polar and hydrophilic ionic liquids possessing low toxicity and high biodegradability. The reaction rates and yields of the products in ionic liquids were greater than those in common organic solvents. The relationship between the structure of the ionic liquid used and the structure of the heterocyclic compound was investigated.

Open access

V. Freidenfelds and P. Mekšs

Investigation of three colour inks was performed using the HPLC method. The research is based on the theory of reducing of solvent in ink and on the change of ratio between dyes due to the degradation of the dye or changes of its extraction properties. Old samples, aged from 1 to 7 months were selected for research. Samples were made using blue, violet and black ballpoint ink. Record samples are kept in the dark, in climatic conditions of a usual office. During the identification of ink compound, by using LC/MS, a statement was made that each ink sample contains 2-phenoxyethanol as a solvent, Methyl Violet and Basic Blue dyes and their degradation products. The areas of peaks gained at characteristic wavelengths are used for the analysis of the aging process.

Open access

A. Podjava, P. Mekss, A. Zicmanis and S. Krasnov

Gas-phase chemical properties of several (1-methylimidazol-3-io)-alkane-1-carboxylates (alkane=ethane, propane and butane) have been investigated in this study. These substances are synthesized using classical transformations and analyzed in positive ionization mode using collision-induced dissociation (0-50 eV). These experiments were carried out in both deuterated and undeuterated solvent media. The data obtained in this study show, that carboxylate group weakly influences fragmentation of zwitterionic imidazolium carboxylates in positive electrospray mode. On the other hand, these compounds exert a tendency to form various adducts with sodium and potassium ions and to participate in hydrogen/deuterium exchange in the gas phase.