Wojciech Ostrowski

Mass spectrometric behavior of phenolic acids standards and their analysis in the plant samples with LC/ESI/MS system.

Liquid chromatography coupled to mass spectrometry (MS) with electrospray ionization (ESI) is one of analytical techniques to obtain accurate results of low molecular weight aromatic compounds in biological samples of different origin. The interpretations of mass spectra of these aromatic compounds in the negative spectra registered in the full scan MS mode may be uneasy due to presence of deprotonated molecules [M-H](-) from different co-eluting entities, fragment ions created after the break-up of precursor ions and also ions representing modified molecules clusters. Thus, the first aim of this study was to evaluate general parameters during analysis performed in the full scan MS or MS/MS mode. Secondly, to set general fragmentation rules for aromatic compounds and entities in a complex biological matrix. We established that different groups of low molecular weight phenolic acids form unique adduct ions and additionally registration LC/MS/MS spectra with two different collision energies may allow for differentiating isomeric or isobaric molecules. These findings together with some general fragmentation rules can facilitate identifications of aromatic acids as we outlined in the sample of cold-pressed rose-hip oil and lupine leaves extract.

Formation of diclofenac molecular ions as the effect of Cu(2+)-π interaction under electrospray ionization mass spectrometry conditions.

Solutions containing diclofenac (M) and a copper salt [CuCl2, Cu(ClO4)2, Cu(NO3)2, CuSO4) were analysed by electrospray ionisation mass spectrometry (ESI-MS). Because of the cation–π interactions in diclofenac-Cu(II) complexes, the diclofenac molecular ion M+* at m/z 295 was formed. It was found that the solvent composition (methanol versus water/methanol) and counter ion strongly affect the M+* ion formation. Formation pathways of ion M+* are discussed.

Demethoxycurcumin-Metal Complexes: Fragmentation and Comparison with Curcumin-Metal Complexes, as Studied by ESI-MS/MS

Two questions are asked: the first is if the lack/presence of methoxyl moiety at aromatic ring essentially affects the stability of curcuminoid-metal complexes, and the second is if it is possible that in the metal complexes one of the possible demethoxycurcumin structures predominates. To answer the first question, the ESI-MS/MS spectra were taken of ions containing demethoxycurcumin, curcumin, and metal cation (e.g., ion [dCurc

Multinuclear magnetic resonance studies of 2-aryl-1,3,4-selenadiazoles

2‐Aryl‐1,3,4‐selenadiazoles were studied by 1H, 13C, 15N and 77Se NMR spectroscopy. The results (chemical shifts and coupling constants) were correlated with Hammett substituent parameters as well as calculated chemical shifts and bond lengths. Copyright

Curcuminoids and Acetylacetone: Iron Complexes as Studied by Electrospray Ionization Mass Spectrometry:

Curcumin complexes with iron ions were investigated by electrospray ionization mass spectrometry. It was shown that in methanol solutions of curcumin and iron(III) ions, complexes are formed with a stoichiometry of 1: 1, 2: 1, or 3: 1. Curcumin–iron(II) complexes were created only with the 1: 1 stoichiometry. Abundances of the 1: 1 ions depend on the source of iron [(II) or (III)] and the reduction process of iron(III) by higher cone-voltage values. A counter-ion for the iron cation does not affect the types of formed complexes. For comparison, methanol solutions of acetylacetone (acac) and mixtures of acac and curcumin with iron salts were also investigated.

Formation of curcumin molecular ion under electrospray ionisation conditions in the presence of metal cations.

Electrospray ionisation (ESI) mass spectra obtained for solutions containing curcumin, copper cation and other metal cations, namely Co2+, Ni2+, Mn2+ and Zn2+, have shown an abundant curcumin molecular ion at m/z 368. This ion was not formed for solutions containing curcumin and copper cations or for those containing curcumin and other metal cations. To the best of our knowledge, it is the first example of a system in which copper cations and other metal cations promote formation of organic radical cation under ESI conditions.

Influence of O/S/Se Exchange on the Stability of 1,3,4-Selana(Thia/Oxa)Diazole-Palladium Complexes as Studied by Electrospray Ionization Mass Spectrometry

Abstract The complexes of 2-phenyl-1,3,4-selena(thia/oxa)diazole with a palladium cation were studied by using electrospray ionization mass spectrometry. Palladium chloride was used as a source of palladium cations. The complexes of ligand:metal stoichiometry of 3:1 (ions [L3+PdCl]+) were formed for selenadiazoles and thiadiazoles. Quantum mechanical calculations performed indicated that ligand molecules are attached to palladium cation by the N-4 atom. The fragment ions formed [L2–H+Pd]+ may be regarded as organometallic species. Selenadiazoles were found more prone to form the palladium complexes than thiadiazoles. Oxadiazoles did not yield the respective palladium complexes. For comparison, the nickel cation was also included in the study but only 1:1, and less abundant 2:1 complexes were observed. Exchange of selenium into oxygen does not affect the abilities of the ligands to form nickel complexes. GRAPHICAL ABSTRACT