Cesar Esparza

Objective: Investigation of the ionization and fragmentation behavior of precursor ions enables improvement of qualitative analytical approaches for pharmaceutical substances without using chromatographic separation. Identification of diagnostic product ions additionally facilitates the development of quantitative mass‑spectrometric methods based on MRM/SRM transitions and expands libraries of diagnostic mass ions for the studied drugs. Materials and Methods: Mass spectra of precursor and product ions of prospidium chloride were obtained using a High‑Performance Liquid Chromatograph—Triple Quadrupole Mass Spectrometer LCMS‑8050 equipped with electrospray ionization (ESI) and direct sample introduction (DIP). Results: Five precursor ions at m/z 187.2, 205.2, 373.3, 409.2 and 740.2 were detected and characterized. The most intense precursor ions at m/z 205.2 and 409.2 were selected for collision‑induced dissociation in the collision cell. MS/MS spectral analysis enabled elucidation of fragmentation pathways and the identification of a diagnostic product ion at m/z 164.4. Conclusion: The precursor ions reported here, described for the first time, can be used to broaden existing normative documentation for prospidium chloride by providing a non‑chromatographic method for authenticity testing. Elucidation of fragmentation mechanisms reveals diagnostic product ions that retain core structural elements of the prospidium chloride molecule and are suitable for development of quantitative mass‑spectrometric assays. Keywords: Prospidium chloride, DIP-ESI-MS/MS, fragmentation mechanism, development of analytical methods

The roots and rhizomes of Rubia tinctorum L. have been widely used both for industrial and medicinal purposes for centuries. The primary biologically active substances from Rubia tinctorum L. roots and rhizomes are anthraquinone derivatives such as ruberythric acid and lucidin-3-primeveroside. Their identification and quantification are carried out by various analytical methods, requiring a complicated sample preparation as well as special reagents and reference samples. However, NMR spectroscopy has no limitations of this kind. In this work, we have developed and validated a new express and standard-free method for the qualitative and quantitative analysis of ruberythric acid and lucidin-3-primeveroside by ¹H NMR spectroscopy in the extracts from the roots and rhizomes of Rubia tinctorum L. In this work, we have optimized the conditions of the sample preparation and registration of ¹H NMR spectra, determined the optimal solvent and reference compound and confirmed the obtained results by HPLC-UV-MS.

We studied the interaction of acyl derivatives of carbocyclic alcohols of steroid structure with nitrogenous bases in the ion source of a “direct analysis in real time” (DART) mass spectrometer. The protonation of esters in the DART plasma is accompanied by the elimination of a corresponding acid (acyl derivatives of cholesterol, β-sitosterol, and estradiol), interaction of the formed cation with a nitrogenous base to yield a derivative with a bound charge. This effect was not observed for cortisone acetate and betamethasone dipropionate, which is consistent with the absence of ions of deacyl derivatives in their DART mass spectra.

We recorded and interpreted DART mass spectra of Hoveyda–Grubbs catalysts with N→Ru and S→Ru coordination bonds. The set of ions formed under DART ionization conditions is similar to those obtained using matrix-assisted laser desorption/ionization mass spectrometry. The optimal conditions (ionization gas, gas flow temperature) for recording DART mass spectra of the studied compounds were determined.

We studied a possibility of using direct analysis in real time (DART) mass spectrometry in combination with in situ derivatization by nitrogenous heterocyclic compounds for the rapid profiling of sterols in sweetened condensed milk. The data obtained are consistent with the detection of plant sterols by gas chromatography–mass spectrometry (GC–MS). The proposed approach can be used to detect vegetable fats in condensed milk, and the time required for the analysis of one sample, including sample preparation, is several times shorter than that in GC–MS.

A comparative analysis of the results of using the method described in GOST (State Standard) 33490-2015, and an original method for the detection and quantification of markers of diary product adulteration with vegetable oils, 4-desmethylsterols, by gas chromatography/electron ionization mass spectrometry was performed. It was shown that, using the original procedure, one can avoid false positive results and reduce the time of analysis.

Технология выделения и анализ липофильных и гидрофильных биологически активных компонентов из семян Nigella sativa L.

This article presents results of the chemical composition study of the seeds oils lipid complex of Nigella Sativa L. grown under various geographic conditions. The task of the comprehensive study of the chemical composition of the plant and its individual parts remains relevant due to the wide spectrum of its pharmacological activity.The aim of this work is a comparative study of the fatty acid composition, a non-saponifiable fraction and the composition of essential oils of Nigella Sativa L. seeds grown in different regions of the world.Materials and methods. The combination of chromatography-mass spectrometry and 1H-NMR spectroscopy methods made it possible to study the qualitative and quantitative composition of Nigella Sativa L. lipid complex seeds. All the experiments were carried out in accordance with the requirements of the State Pharmacopoeia, 14th Ed, given in the corresponding general pharmacopeial monographs.Results. Profiles have been established and the content of fatty acids, sterines, triterpene alcohols, essential oils and thymoquinone found out in the lipid complex, has been estimated. The saponifiable portion of the complex is represented by triglycerides (81.7–95.3%), di(3.9–15.2%) and monoglycerides (0.7–4.1%). They mainly contain linoleic (55.8–60.6%), oleic (21.8–24.6%), palmitic (10.0–12.8%), stearic (2.4–3.2 %) and cis-11.14-eicosadiene (2.3–2.6%) acids. In the lipid complex, the contents of sterines and triterpene alcohols were 0.4–0.7%; up to 70% of the fraction was represented by β-sitosterol (22.5–29.2%), cycloartenol (20.1–36.6%) and 24 methylenecycloartanol (9.5–19.9%). In the trace amounts (up to 1.0%), cholesterol has been detected in all the samples. In the lipid complexes, the content of thymoquinone ranged from 0.7 to 2.6%.Conclusion. A comparative study of the seeds lipid complex of Nigella Sativa L. grown under various geographic conditions, has been carried out. The marker compounds as well as their content standards for determining the authenticity of raw materials (thymoquinone, para-cimen, cis-11.14-eicosadienic acid), have been identified.

On‐spot derivatization has been suggested for the modification of primary amine containing compounds for their analysis by thin‐layer chromatography hyphenated with matrix‐assisted laser desorption ionization mass spectrometry. The proposed approach was based on post‐chromatographic treatment of separated analytes inside the chromatographic zones on the thin‐layer chromatography plates by tris(2,6‐dimethoxyphenyl)methilium reagent. The derivatives, containing permanent positive charge, reveal exceptionally intense peaks of their cationic moieties and high signal/noise ratio in mass spectra recorded directly from the plates. The method was tested on a series of aliphatic, aromatic, and amine‐containing pharmaceuticals.