T15N4
Contents
Time-of-flight mass spectrometer EMG-40-3 – a new high sensitivity instrument for on-line analysis of light gases, including tritium
T15N4
I.I. Pilyugin, V.T. Zhdan, A.V. Kozlovskii
Technical characteristics of time-of-flight mass spectrometer EMG-40-3 are given. It is shown that the instrument sensitivity is two orders of magnitude more than that of EMG-40-2. Resolving power of instrument provides the quantitative on-line analysis of gas mixtures containing helium and hydrogen isotopes as well as tritium.
Chromatomass-spectrometric determination of new antiulcer drug in rats blood plasma
T15N4
K.A. Leonov, D.A. Vishenkova, V.V. Bykov, A.A. Bakibaev
Synthesis of an innovative drug 9-(2,5-dihydroxyphenyl)-2-(4-ethoxyphenyl)-2,3,7,8-tetrahydro-1H-pyrido [1,2-a] pyrazine-1,4(6H)-dione (PPI) for the treatment of peptic ulcer with a new mechanism of action has necessitated the pharmacokinetics study of the substance in the blood plasma and investigation of its absorption and elimination processes. This paper describes the development and validation of a technique for quantitative determination of the new compound PPI in rat blood plasma by HPLC/MS. The method of solid-phase extraction is applied to extract PPI from blood plasma in the process of biological samples preparation. The lower limit of quantification is 0.1 ng ml–1, the linearity range from 0.1 to 1000 ng ml–1. By the developed technique the sample analysis of rats blood plasma was carried out after pharmaceutical PPI substance introduction in a dose of 20 mg kg–1, a pharmacokinetic profile of the substance was established, and pharmacokinetic parameters were calculated that allows one to judge the degree and rate of absorption and excretion of new antiulcer drug in the blood of laboratory rats.
Isomeric effects in collisionally-induced dissociation mass spectra of β-(1→6)-linked cyclic tetrasaccharides of the Glcp2GlcpN2 composition
T15N4
A.O. Chizhov , M.L. Gening, O.A. Pinsker, Yu.E. Tsvetkov, N.E. Nifantiev
Electrospray ionization high resolution mass spectra of positively charged ions (the first and the second order) of protonated molecules of isomeric β-(1→6)-linked cyclic tetrasaccharides of the Glcp2GlcpN2 composition were recorded and interpreted. It was shown that the second-order mass spectra of these compounds have some differences reflecting the mutual position of the glucopyranose and glucosamine residues. The most significant qualitative differences were observed for MS/MS spectra of doubly protonated, doubly charged molecules.
Controlling the resolution of static mass spectrometers using intermediate slit diaphragms
T15N4
A.S. Antonov, A.S. Berdnikov, L.N. Gall, V.D. Sachenko
The paper shows how to increase effectively the resolving power and transmission of a static mass spectrometer (implying here an optimal compromise between these parameters) using the optimally positioned intermediate slit diaphragms in order to ensure a minimum loss of the sensitivity of a device.
Studying of handwritten strokes aging kinetics by high-performance liquid chromatography/mass spectrometry
T15N4
D.I. Baygildieva, , T.M. Baygildiev, О.A. Shpigun, I.A. Rodin
One of the central problems of documents forensic examination is the determination of the ink deposition date by such common writing instruments as ballpoint pens. To solve this problem, it is necessary to get information about the composition of ballpoint pen inks that were used for depositing inks, to get information about qualitative and quantitative changes of components undergoing in time after depositing inks on a document, as well as to know changes in the composition and properties of the ink caused by environmental influences or intentional effects on document such as photo-, thermal-, UV-, IR-radiations, microwave and other types of external influences.
Therefore, the purpose of this research was to develop an approach that allows one to detect changes and establish dependence of these changes in the ballpoint pen composition that occur in strokes over time. As a result of this study, the possibilities of liquid chromatography/mass spectrometry for the detection of changes over time in the composition of ballpoint pen inks BIC Original, Corvina 51 and Pilot were estimated. Modeling of the dyes degradation under the influence of UV radiation on strokes was carried out. Kinetic parameters that describe the degree of dyes conversion were determined.
On the correct averaging of the equations of ion motion in high-frequency electric fields
T15N4
A.S. Berdnikov, A.N. Verenchikov, A.G. Kuzmin
Pseudo potential approach is a useful tool to describe qualitatively the motion of ions in inhomogeneous radio frequency electric fields often used in mass spectrometric devices. However, in the theoretical analysis of ion motion in radio-frequency electric fields with close frequencies, a mathematical ambiguity arises, caused by the lack of equivalence of different mathematical approaches. The paper considers and compares the time-dependent pseudopotential model and the model of solenoidal (vortex) pseudo forces. It is shown that the vortex drift model in radio-frequency electric fields with close frequencies can be replaced by the model of ion motion in a pseudopotential that varies in time. The theory of almost periodic time signals with two characteristic time scales, fast and slow, makes it possible to eliminate ambiguity when choosing the correct mathematical method for describing the motion of ions in radio-frequency electric fields.