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Electrospray Interface (electrospray + interface)
Selected AbstractsCapillary electrophoresis-laser induced fluorescence-electrospray ionization-mass spectrometry: A case studyELECTROPHORESIS, Issue 7-8 2005Carolin Huhn Abstract The simultaneous hyphenation of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection and electrospray ionization-mass spectrometry (ESI-MS) as a novel combined detection system for CE is presented. ,-Carbolines were chosen as model analytes with a forensic background. Nonaqueous CE as well as conventional CE with an aqueous buffer system are compared concerning efficiency and obtainable detection limits. The distance between the optical detection window and the sprayer tip was minimized by placing the optical cell directly in front of the electrospray interface. Similar separation efficiencies for both detection modes could thus be obtained. No significant peak-broadening induced by the MS interface was observed. The high fluorescence quantum yield and the high proton affinity of the model analytes investigated resulted in limits of detection in the fg (nmol/L) range for both detection methods. The analysis of confiscated ayahuasca samples and ethanolic plant extracts revealed complementary selectivities for LIF and MS detection. Thus, it is possible to improve peak identification of the solutes investigated by the use of these two detection principles. [source] An automated, sheathless capillary electrophoresis-mass spectrometry platform for discovery of biomarkers in human serumELECTROPHORESIS, Issue 7-8 2005Alexander P. Sassi Abstract A capillary electrophoresis-mass spectrometry (CE-MS) method has been developed to perform routine, automated analysis of low-molecular-weight peptides in human serum. The method incorporates transient isotachophoresis for in-line preconcentration and a sheathless electrospray interface. To evaluate the performance of the method and demonstrate the utility of the approach, an experiment was designed in which peptides were added to sera from individuals at each of two different concentrations, artificially creating two groups of samples. The CE-MS data from the serum samples were divided into separate training and test sets. A pattern-recognition/feature-selection algorithm based on support vector machines was used to select the mass-to-charge (m/z) values from the training set data that distinguished the two groups of samples from each other. The added peptides were identified correctly as the distinguishing features, and pattern recognition based on these peptides was used to assign each sample in the independent test set to its respective group. A twofold difference in peptide concentration could be detected with statistical significance (p -value < 0.0001). The accuracy of the assignment was 95%, demonstrating the utility of this technique for the discovery of patterns of biomarkers in serum. [source] ,, ,-Unsaturated sulfophenylcarboxylates as degradation intermediates of linear alkylbenzenesulfonates: Evidence for ,-oxygenation followed by ,-oxidations by liquid chromatography-mass spectrometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2002Peter Eichhorn Abstract Liquid chromatography with an electrospray interface to a mass spectrometer (LC-ES-MS) and LC-ES coupled to a tandem MS (LC-ES-MS/MS) were used to detect and identify intermediates excreted transiently during the aerobic degradation of linear alkylbenzenesulfonates (LAS) in fixed-bed bioreactors (FBBR). The inoculum for the FBBR was the microflora of the River Rhine, Germany. Two major phenomena were observed on the addition of 100 mg/L LAS to the system, sorption and then biodegradation. Disappearance due to sorption was followed in an inhibited FBBR. Biodegradation of LAS started on day 7 and was accompanied by the transient excretion of intermediates, which were later largely degraded. We detected not only the sulfophenylcarboxylates (SPCs) observed previously but also the ,, ,-unsaturated SPCs (SPC-2H), which have not been reported before. Experiments with the (4-sulfophenyl)dodecanes (C12-LAS), which had minor contaminants of C11-LAS, showed C12-, C10-, C8-, C6-, and C4-SPCs when LAS was degraded as well as traces of C9-, C7-, and C5-SPCs. Signals from the SPC-2H species were usually some 10% of those from the corresponding SPCs. Samples from these experiments were also examined by gas chromatography-mass spectrometry (GC-MS), but no desulfonated intermediates were detected. We interpret the data to mean that the only attack on LAS was by ,-oxygenation; there was no visible initial desulfonation. The products of ,-oxygenation were oxidized to the corresponding SPC and subject to ,-oxidation, as evidenced not only by the pattern of C-2 units in the excreted SPCs but also in the corresponding series of SPC-2H, representing the intermediates in ,-oxidation. [source] Analysis of tricyclic antidepressant drugs in plasma by means of solid-phase microextraction-liquid chromatography-mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2007Claudete Alves Abstract Solid-phase microextraction coupled to liquid chromatography and mass spectrometry (SPME-LC-MS) was used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. SPME was performed by direct extraction on a PDMS/DVB (60 µm) coated fiber, employing a stirring rate of 1200 rpm for 30 min, pH 11.0, and temperature of 30 °C. Drug desorption was carried out by exposing the fiber to the liquid chromatography mobile phase for 20 min, using a labmade SPME-LC interface at 50 °C. The main variables experimentally influencing LC-MS response were evaluated and mathematically modeled. A rational optimization with fewer experiments was achieved using a factorial design approach. The constructed empirical models were adjusted with 96,98% of explained deviation allowing an adequate data set comprehension. The chromatographic separation was realized using an RP-18 column (150 mm × 2.1 mm, 5 µm particles) and ammonium acetate buffer (0.01 mol/l, pH 5.50) : acetonitrile (50 : 50 v/v) as mobile phase. Low detection levels were achieved with electrospray interface (0.1 ng/ml). The developed method showed specificity, linearity, precision, and limit of quantification adequate to assay tricyclic antidepressant drugs in plasma. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||