Vol 73, No 14 (2018)

Static mass analyzers offer a unique potential opportunity to achieve 100% utilization of ions generated by a continuously operating ion source. However, to achieve this, it is necessary for the mass analyzer to operate in the spectrographic mode rather than in the spectrometric mode. It is known that the conventional Mattauch–Herzog scheme may operate in the spectrographic mode with double focusing (by both angle and energy) along the straight focal line but only in the first order. The usage of more complex optical solutions is prevented by the fringing fields of static magnets, which destroy the exact spectrographic mode of the instrument operation. It is shown in the presented study that by using the principle of the similarity of trajectories in Euler-homogeneous fields one can purposefully synthesize asymmetric fringing magnetic fields of a particular type, which keep the spectrographic mode and the straightness of the focus line for static mass analyzers. Such fringing fields and the corresponding fringing configurations of magnetic poles and screens can become a basis for static mass spectrographs of a new type with high optical characteristics.

A new method of the derivatization of alcohols for their analysis by matrix-assisted laser desorption/ionization (MALDI) and surface-assisted laser desorption/ionization (SALDI) is proposed. The approach is based on the silylation of the analytes with bromomethylchlorodimethylsilane in the presence of tertiary amines to yield fixed-charge containing derivatives. The proposed method was tested using aliphatic alcohols, terpenols, and sterols. MALDI and SALDI mass spectra of all derivatives contain intense ion peaks corresponding to their cationic parts.

The paper describes the high-precision U-isotope analysis of rocks. The analysis is based on multicollector inductively coupled plasma mass spectrometry (MC−ICP−MS) and includes, as an essential part, the three-step ion-exchange chromatography separation of uranium from chemically complex solutions. In the analysis, the ²³⁵U and ²³⁸U mass-bias of the MC−ICP−MS is corrected against the reference ratio of ²³³U and ²³⁶U in a double-spike added. The doublespiking precedes sample chemical digestion. This approach is useful as it corrects isotope data for a possible U-isotope fractionation that could have occurred in the chemical preparation of samples. The double-spike ²³⁶U/²³³U is 1.03183 ± 0.00005. The extraction procedure ensures uranium yield of more than 80%. The accuracy of the analysis was estimated by the study of ²³⁸U/²³⁵U in an international standard sample IRMM-3184 as well as in monitor samples. The uncertainty was estimated at ±0.008% (2SD), which is comparable with the accuracy of the results previously published by foreign researches. The analysis was elaborated for studying natural ²³⁸U/²³⁵U ratio variations. It was used by the authors for the high-precision determination of the U-isotope composition in rocks (granites, shales, volcanic rocks) and U-bearing minerals.

A possibility of using a number of aromatic and heteroaromatic carboxylic acids and their halogen anhydrides as reactive matrix compounds for the analysis of alcohols of different structures by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has been studied. It is shown that the acylation of alcohols with nicotinic and quinoline-6-carboxylic acid chlorides gives derivatives with high desorption/ionization efficiency under MALDI conditions, and that the free acids formed as a result of the hydrolysis of anhydrides act as matrix compounds. The proposed approach is tested on a number of aliphatic, alicyclic, and aromatic alcohols.

The identification of protein biomarkers of chemical warfare agents involves their reliable detection in the blood plasma at trace levels. This is a challenging task in the modern liquid chromatography–mass spectrometry. Existing approaches are based on the formation of tyrosine adducts with alkylmethylphosphonic acids after the cleavage of all proteins. The structure of such adducts is related to the type of the chemical agent used. This study demonstrates the possibility of detecting the tripeptide adduct of isopropylmethylphosphonic acid, obtained by trypsinolysis of the albumin adduct with sarin, in human plasma. The study of the pathways of fragmentation of the analyte ensures the identification of the characteristic features of dissociation that can be used to determine other biomarkers of the application of chemical weapons. The conditions for recording the most intense ion transitions to perform the rapid screening of blood plasma samples for the concentration of the albumin adduct of sarin by filtration with trypsinolysis are proposed.

A method of total saturated and total aromatics determination in oils and oil products by electron ionization mass spectrometry is presented. The contribution of saturated and aromatic hydrocarbons to the total ion current is found by solving a system of linear equations with coefficients that take stock a mutual interference of the mass spectra of saturated and aromatic hydrocarbons.

The paper presents proposals for the mass spectrometric determination of β-adrenoreceptor modulators by bifunctional derivatization with N-methyl-N-(trimethylsilyl)-trifluoroacetamide followed by acylation with pentafluoropropionic or heptafluorobutyric anhydrides with a description of the derivatives obtained.