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(1/160) Matrix-assisted laser desorption/ionization mass spectrometric analysis of uncomplexed highly sulfated oligosaccharides using ionic liquid matrices.

Direct UV matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis of uncomplexed, underivatized, highly sulfated oligosaccharides has been carried out using ionic liquids as matrices. Under conventionally used MALDI time-of-flight experimental conditions, uncomplexed polysulfated oligosaccharides do not produce any signal. We report that 1-methylimidazolium alpha-cyano-4-hydroxycinnamate and butylammonium 2,5-dihydroxybenzoate ionic liquid matrices allow the detection of picomole amounts of the sodium salts of a disaccharide, sucrose octasulfate, and an octasulfated pentasaccharide, Arixtra. The experimental results indicate that both analytes undergo some degree of thermal fragmentation with a mass loss corresponding to cleavage of O-SO3Na bonds in the matrix upon laser irradiation, reflecting lability of sulfo groups.  (+info)

(2/160) Ionic liquid-derived blood-compatible composite membranes for kidney dialysis.

A novel heparin- and cellulose-based biocomposite is fabricated by exploiting the enhanced dissolution of polysaccharides in room temperature ionic liquids (RTILs). This represents the first reported example of using a new class of solvents, RTILs, to fabricate blood-compatible biomaterials. Using this approach, it is possible to fabricate the biomaterials in any form, such as films or membranes, fibers (nanometer- or micron-sized), spheres (nanometer- or micron-sized), or any shape using templates. In this work, we have evaluated a membrane film of this composite. Surface morphological studies on this biocomposite film showed the uniformly distributed presence of heparin throughout the cellulose matrix. Activated partial thromboplastin time and thromboelastography demonstrate that this composite is superior to other existing heparinized biomaterials in preventing clot formation in human blood plasma and in human whole blood. Membranes made of these composites allow the passage of urea while retaining albumin, representing a promising blood-compatible biomaterial for renal dialysis, with a possibility of eliminating the systemic administration of heparin to the patients undergoing renal dialysis.  (+info)

(3/160) Liquid matrix deposition on conductive hydrophobic surfaces for tuning and quantitation in UV-MALDI mass spectrometry.

With its highly fluctuating ion production matrix-assisted laser desorption/ionization (MALDI) poses many practical challenges for its application in mass spectrometry. Instrument tuning and quantitative ion abundance measurements using ion signal alone depend on a stable ion beam. Liquid MALDI matrices have been shown to be a promising alternative to the commonly used solid matrices. Their application in areas where a stable ion current is essential has been discussed but only limited data have been provided to demonstrate their practical use and advantages in the formation of stable MALDI ion beams. In this article we present experimental data showing high MALDI ion beam stability over more than two orders of magnitude at high analytical sensitivity (low femtomole amount prepared) for quantitative peptide abundance measurements and instrument tuning in a MALDI Q-TOF mass spectrometer. Samples were deposited on an inexpensive conductive hydrophobic surface and shrunk to droplets <10 nL in size. By using a sample droplet <10 nL it was possible to acquire data from a single irradiated spot for roughly 10,000 shots with little variation in ion signal intensity at a laser repetition rate of 5-20 Hz.  (+info)

(4/160) Ionic liquid matrix for direct UV-MALDI-TOF-MS analysis of dermatan sulfate and chondroitin sulfate oligosaccharides.

Polyanionic oligosaccharides such as dermatan sulfate (DS) and chondroitin sulfate (CS) exhibit poor ionization efficiencies and tend to undergo thermal fragmentation through the loss of SO(3) under conventional ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) conditions. A new ionic liquid matrix (ILM), a guanidinium salt of alpha-cyano-4-hydroxycinnamic acid, facilitates direct UV-MALDI mass spectrometric (MS) analysis of underivatized DS and CS oligosaccharides up to a decasaccharide in their common form as sodium salts. The resulting mass spectra show very low extent of fragmentation through an SO(3) loss. The new ILM is suitable for MALDI-MS analysis of mixtures containing oligosaccharides with different numbers of sulfo groups.  (+info)

(5/160) Palladate salts from chiral pyridinium ionic liquids: synthesis and crystal structures.

This paper reports the preparation, characterization and the crystal X-ray structures of metal-containing ionic liquid complexes based on chiral pyridinium cations and tetrachloropalladate (II) [PdCl4]2-.  (+info)

(6/160) Ionic liquid-promoted ring-closure reactions between 1,4-dihydroxyanthraquinone and diamines.

The reaction of 1,4-Dihydroxyanthraquinone with diamines was carried out in the presence of CuCl(2), CuCl in the ionic liquid [Bmim]PF(6), [Bmim]BF(4) or [Bmim]Cl x CuCl.  (+info)

(7/160) L-proline catalyzed Michael additions of thiophenols to alpha,beta-unsaturated compounds, particularly alpha-enones, in the ionic liquid [bmim]PF6.

L-proline catalyzed additions of 13 different thiols to 11 different alpha-enone Michael acceptors in [bmim] PF(6 )are reported. Reasonable to high yields of the reaction products were isolated in most cases.  (+info)

(8/160) Self-associated, "distillable" ionic media.

Liquid or low melting association products of carbon dioxide and a secondary amine, both neutral molecules that may be gaseous, are recognised as "distillable" ionic media.  (+info)