European Journal of Mass Spectrometry最新文献

The approach to quantitative analysis by silicon Surface Assisted Laser Desorption Ionization Mass Spectrometry (Si-SALDI) is proposed. The approach is based on the new method for forming an active surface layer on a silicon substrate by exposing to laser radiation directly in the ion source of a mass spectrometer. The method can be used repeatedly on the same substrate, providing high reproducibility of its surface ionization properties and high ionization efficiency of organic compounds. Within the proposed approach, the methods of improvement of signal reproducibility are also considered, including continuous monitoring of the silicon surface ionization properties using a Knudsen effusion cell; scanning the surface of a silicon substrate with a laser beam; selecting the optimal value of laser fluence and using a reproducible sample introduction technique. It is demonstrated that this approach can be successfully applied to quantify clinically relevant concentrations of pharmaceutical drugs in extracts of blood.

The process of nonlinear resonant excitation of ion oscillations in a linear trap is studied. There is still no detailed simulation of the resonance peak in the literature. We propose to use the excitation contour to describe the collective ion resonance. The excitation contour is a resonant mass peak obtained by the trajectory method with the Gaussian distribution of the initial coordinates and velocities. The following factors are considered: excitation time, low order hexapole and octopole harmonics with amplitudes A₃ and A₄, the depth of the initial ion cloud position. These multipoles are used for selective ion ejection from linear ion trap. All these factors affect the ion yield and the shape of the contours. Obtained data can be useful for control of such processes as ion fragmentation, ion isolation, ion activation, and ion ejection. Simulated resonance peaks are important for the theoretical description of the ion collective nonlinear resonances.

We investigate the dynamics of an ion confined in a Paul-trap supplied by a fractional periodic impulsional potential. The Cantor-type cylindrical coordinate method is a powerful tool to convert differential equations on Cantor sets from cantorian-coordinate systems to Cantor-type cylindrical coordinate systems. By applying this method to the classical Laplace equation, a fractional Laplace equation in the Cantor-type cylindrical coordinate is obtained. The fractional Laplace equation is solved in the Cantor-type cylindrical coordinate, then the ions is modelled and studied for confined ions inside a Paul-trap characterized by a fractional potential. In addition, the effect of the fractional parameter on the stability regions, ion trajectories, phase space, maximum trapping voltage, spacing between two signals and fractional resolution is investigated and discussed.

In the present study, anthocyanin pigments from red sorghum (Sorghum bicolor) bran were identified and characterized by Liquid Chromatography-Electron Spray Ionization Mass Spectrometry. The individual anthocyanins were identified by comparing their mass spectrometric data and retention times, published data. 3-deoxyanthocyanidins and methyl 3-deoxyanthocyanidins were identified in red sorghum bran. This paper presents complete LCMS profile and MS spectrometric data of red sorghum bran.