Intensive development of oil and gas industries in the Arctic threatens Arctic aquatic ecosystems. Toxic and primarily lethal cardiotoxic effects of oil in living organisms are believed to be associated with polyaromatic hydrocarbons (PAHs), and previous works revealed the electrophysiological mechanisms of action of individual oil-derived PAHs. However, the physiological effects of a complex PAH mixture in an oil water-soluble fraction (WSF) have not been previously studied. This study is focused on the effects of WSF of oil on electrical activity and major ionic currents in the working myocardium of navaga (Eleginus nawaga), which is one of the most important commercial fish species in the Arctic. The authors found that 1 and 10

Complex compounds of Cu, Ag, Pd, Pt, and Au with dithizone (diphenylthiocarbazone) were studied by surface-assisted laser desorption/ionization from nanocrystalline silicon. The study demonstrated that all investigated complexes ionize efficiently in the negative ion mode, forming molecular ions and one or more types of fragment ions. The limits of detection for the metal dithizonates were determined. A possibility of coupling laser desorption/ionization mass spectrometry with single drop microextraction for metal detection was explored. Factors affecting the concentration factor were examined, and the optimal conditions for performing single drop microextraction in gold determination were found. The limit of detection for gold is 5 pg/mL.

A new bismuth complex with the N-(5,6-dihydro-4H-1,3-thiazin-2-yl)benzamide ligand (L = C11H13N2OS) was synthesized for further medical use. The complex and the ligand exhibit anticancer activity. The structure of the complex was characterized by NMR spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and laser-induced electron transfer desorption/ionization (LETDI) mass spectrometry. The Bi: L ratio is 1: 1; the components are connected by an ionic (ion-dipole) interaction. The reaction of bismuth(iii) chloride with ligand hydrobromide (L•HBr) affords the complex (C11H13N2OS)3[Bi2Cl9]. The composition of this complex was confirmed by X-ray diffraction, ICP-AES, and LETDI methods.

A new polyfunctional ligand of the thiadiazole family was synthesized. Cytotoxic properties with respect to leukemic cell lines, radiation stability, predicted permeability through the blood–brain barrier and cardiotoxicity of the new ligand and its precursor were determined. New zinc complexes with N-{2-[5-(3-chloro-4-methylphenylamino)-1,2,4-thiadiazol-3-yl]-1-methylethyl}-N-(2,2,6,6-tetramethylpiperidin-4-yl)-amine as the ligand have been obtained.

The results of a study of the analytical characteristics of a mass spectrometric method based on atmospheric pressure laser plasma-induced ionization in the negative ion detection mode. The investigation focuses on the determination of 2,4-dinitrophenol, 2,5-dinitrophenol, 2-nitro-4-chlorophenol, 2,4-dichlorophenol, 2,4-dinitrotoluene, m -dinitrobenzene, and 3,3'-dinitrobiphenyl. Depending on their chemical properties, nitroaromatic compounds are ionized to form deprotonated molecules and/or molecular ions (radical anions). Calibration dependences for these compounds were plotted, and sensitivity coefficients were determined. The research demonstrates that sensitivity depends on the nature and position of substituents in the aromatic ring. The limits of detection for nitroaromatic compounds were estimated to be within the range 1–30 pg.

An Erratum to this paper has been published: https://doi.org/10.1134/S1061934822370018

Surface layers of molybdenum oxide MoO3 and tungsten oxide WO3 produced by thermal oxidation of molybdenum and tungsten plates in the air were studied for the first time as a platform for laser-induced electron transfer desorption/ionization. High analytical performance of such layers for the determination of metal complexes with dithiocarbamates, such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and diethyldithiocarbamate, has been demonstrated. All studied complexes are detected as radical cations, with no fragment ions. The ion yields from MoO3 and WO3 surfaces were found to be more than two orders of magnitude higher than those from nanocrystalline silicon surfaces. A novel method has been developed for the determination of trace amounts of dithiocarbamates based on the complexation of analytes with gold ions, followed by laser-induced electron transfer desorption/ionization. The limits of detection of dithiocarbamates were estimated to be about 1 ng/mL. The proposed method was successfully applied to the rapid screening of tetramethylthiuram disulfide residues in juice.

Crystals of two copper complexes with N-(5,6-dihydro-4H- +1,3-thiazin-2-yl)benzamide were obtained and characterized by X-ray diffraction analysis. LETDI studies have shown that the composition of the complex is inhomogeneous, and the precipitated crystals can have different structures being of Cuii or Cui–Cuii types. The complexes are significantly more cytotoxic toward the leukemic Jurkat cell line than to healthy lymphocytes.

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.

A lot of animal models are developed with aim to advance in atrial fibrillation (AF) understanding. The hybrid B6CBAF1 mice are used extensively as a background to create manifestation of various diseases, however, their atrial electrophysiology, autonomic sympathetic innervation of the heart and potential for AF investigation is poorly characterized. In the present study we used ECG and microelectrode recordings from multicellular atrial preparations to reveal attributes of atrial electrical activity in B6CBAF1. Also, experiments with a fluorescent false monoamine neurotransmitter and glyoxylic acid-based staining were carried out to characterize functionally and morphologically catecholaminergic innervation of the B6CBAF1 atria. Atrial myocardium of B6CBAF1 is highly prone to ectopic automaticity and exhibits abnormal spontaneous action potential accompanied by multiple postdepolarizations that result in proarrhythmic triggered activity unlike two parental C57Bl/6 and CBA strains. In vivo experiments revealed that B6CBAF1 hybrids are more susceptible to the norepinephrine induced AF. Also, sympathetic nerve terminals are partially dysfunctional in B6CBAF1 revealing lower ability to accumulate and release neurotransmitters unlike two parental strains. The analysis of the heart rate variability revealed suppressed sympathetic component of the autonomic heart control in B6CBAF1. The organization of sympathetic innervation is very similar morphologically in all three murine strains however the abundance of non-bifurcated catecholamine-positive fibers in B6CBAF1 was increased. These results suggest that B6CBAF1 mice exhibit enhanced intrinsic atrial proarrhythmicity, while the abnormalities of sympathetic neurotransmitter cycling probably underlie disturbed autonomic heart control.

A copper complex with N-(5,6-dihydro-4H-1,3-thiazin-2-yl)benzamide was synthesized for the first time and characterized by 1H NMR spectroscopy, LETDY mass spectrometry, and elemental analysis. A comparative study of the obtained complex and copper 2-aminopyrimidine complex was performed by flow cytometry on normal lymphocytes and Jurkat cells. Complexes with radionuclides 64,67Cu (with and wihout a carrier) were prepared, and distribution of the labeled complexes in the organs of mice was considered. Packing in carboxymethylcellulose-based microgels was proposed as a transport form for the complexes. The results show a promise of the obtained materials as potential radiopharmaceutical agents.

A method for the chemical modification (derivatization) of ions obtained by surface assisted laser desorption/ionization (SALDI) is proposed. Derivatization is based on the interaction of desorbed ions with alcohol molecules. The method is simple, does not affect the duration of analysis and ensures the improvement of the analytical characteristics of the SALDI method, when analysis is carried out under the conditions of peak interference and strong fragmentation of analyte ions. The efficiency of the method is demonstrated in the determination of caffeine, pyrrolidine, and diphenhydramine under the conditions of atmospheric pressure sample application.

Two new versions of surface-assisted laser desorption/ionization method are considered. One version is based on a combination of this method with thermal desorption sample injection and may be applied for determination of chemical compounds that are transformed into a gas phase without decomposition by heating. Another version is based on laser-induced electron-transfer desorption/ionization and could be used for determination of compounds with low proton affinity. The possibilities of the new approaches are illustrated by the example of determination of aminoacids, medical compounds, chlorophyll, as well as gold in sulfide ores.

The results of comparative analysis of laser desorption/ionization, matrix-assisted laser desorption/ ionization, and new laser-induced electron transfer desorption/ionization methods, used to detect chlorophyll A; mercury complex with thiuram; platinum complex with mercaptoquinoline; and lutetium complex with phthalocyanine, modified by crown ether, are presented. The new method is found to have a better ionization efficiency for complex compounds than the conventional laser desorption/ionization methods.

The Pd, Mn, La, and Rh complexes with the heterocyclic azo compounds were studied by the laser-induced electron transfer desorption/ionization (LETDI) method. The optimum parameters of laser irradiation were found, and the compositions of the complexes were determined. The quantum chemical simulation of the compositions of the complexes was performed on the basis of the data of mass spectrometry. It is shown that laser-induced electron transfer desorption/ionization is an effective tool for the high-sensitive determination and identification of metal complexes.

Four different substrates, namely, graphite, tungsten, amorphous silicon (α-Si) and titanium dioxide (TiO2) films, were compared in view of the laser-induced electron transfer desorption/ionization (LETDI) of metal coordination complexes. A rhenium complex with 8-mercaptoquinoline, a copper complex with diphenylthiocarbazone and chlorophyll A were studied as the test analytes. The dependencies of the ion yield and the surface temperature on the incident radiation fluence were investigated experimentally and theoretically. The temperature was estimated using the numerical solution of a one-dimensional heat conduction problem with a heat source distributed in time and space. It was found that at the same temperature, the ion yield from the different substrates varies in the range of three orders of magnitude. The direct comparison of all studied substrates revealed that LETDI from the TiO2 and α-Si films offer a better choice for producing molecular ions of metal coordination complexes.

Thin titanium dioxide (TiO2) films were studied as ion emitters for the laser-induced electron transfer desorption/ionization (LETDI) of metal complexes with organic reagents. The TiO2 films (350 nm thick) were deposited on the silicon substrates by e-beam evaporation of TiO2 powder. Copper complex with phthalocyanine, rhenium complex with thiocarbanilide and platinum complex with 8-quinolinethiol were studied as the test analytes. Reflectron time-offlight mass spectrometer with the rotating ball interface was used for analysis. The analytes were applied on the surface of TiO2 film using an electrospray deposition. All tested compounds are detected as the radical molecular ions with no fragmentation. It is found, that TiO2 films are very stable and show good sensitivity in examined range of the analyte concentrations. The limits of detection of studied complexes were at the subfemtomole range, and the relative standard deviation was less than 10%.

The mechanism of ion desorption in the process of laser desorption/ionization from silicon surfaces is studied using pyridine and N,N-dimethyl-1-phenylethylamine as examples. Based on the experimental and theoretical results, dependences of ion signal on the surface temperature are obtained for two different wavelengths of laser radiation, 355 nm and 532 nm. The theoretical part of the work includes numerical calculations of surface temperatures of amorphous silicon using the SLIM software package and quantum-chemical calculations of binding energy between the ions and silicon surface using the Hartree-Fock method and Firefly software package. It is demonstrated that the ions are desorbed via a thermal mechanism at temperatures much lower than the melting point of amorphous silicon.

The efficiency of laser desorption/ionization of twenty compounds from the surface of amorphous silicon is studied as a function of proton affinity (PA) and gas-phase basicity (GB). The values of GB and PA are obtained from quantum-chemical calculations using the density functional theory in the B3LYP model with the 6–311++G(3df,3pd) basis set. The values of GB lie in the range from 845 to 977 kJ/mol. The efficiency of laser desorption/ionization exponentially depends on the GB and PA values and for the studied compounds varies from 7 × 10−6 to 1.4 × 10−2.