an air–assisted liquid–liquid microextraction method for the extraction and preconcentration of trace amounts of some synthetic phenolic antioxidants in biological fluids followed by their determination by gas chromatography–flame ionization detection has been reported. in this method the target analytes are extracted into a few microliters of carbon tetrachloride (extraction solvent) from an a...

Background and aims: A selective and sensitive high performance liquid chromatography-electrospray ionization mass spectrometry method has been established for determination of methotrexate in human plasma. Methods: Methotrexate was extracted from plasma with acetonitrile. The mobile phase consisted of acetonitrile-water-formic acid 74: 25: 1(v/v). Twenty...

Cocrystallization between analyte and matrix is required by matrix-assisted laser desorption/ionization and can represent a significant limitation of the technique. A molecular beam expansion, mass spectrometric method has been developed to explore the possibility of using pure solvents as matrix to avoid cocrystallization. Two kinds of solvent, liquid CS2 and liquid or supercritical CO2, have ...

The development and illustrative applications of an ambient ionization technique termed Venturi easy ambient sonic-spray ionization (V-EASI) is described. Its dual mode of operation with Venturi self-pumping makes V-EASI applicable to the direct mass spectrometric analysis of both liquid (V(L)-EASI) and solid (V(S)-EASI) samples. V-EASI is simple and easy to assemble, operating solely via the a...

A quantitative analysis method for fudosteine in human serum by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI/MS/MS) was established, which shows high sensitivity and selectivity. The mobile phase composition was 75% 20 mM acetic acid and 25% acetonitril, which was pumped at a flow rate of 0.40 mL/min. The overall chromatographic run time was ...

A quantitative analysis method for fudosteine in human serum by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI/MS/MS) was established, which shows high sensitivity and selectivity. The mobile phase composition was 75% 20 mM acetic acid and 25% acetonitril, which was pumped at a flow rate of 0.40 mL/min. The overall chromatographic run time was ...

time-dependent schrödinger equation for a 1-d model of hydrogen molecular ion h2+ in intenselaser field linearly polarized along the molecular axis is solved. ionization rates are calculated for differentinitial states. the evolution of electronic wavefunction at fixed inter-nuclear separations are simulated andanalyzed. the results obtained for the ground state of this 1-d model of h2+ show ap...

A selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of berberine, palmatine and jatrorrhizine in rat plasma. Target compounds, together with the internal standard (metronidazole), were extracted from rat plasma samples by protein precipitation with acetonitrile-methanol (1:2, v/v). Chromatography was carried out using a ...