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Gaussian and exponentially modified Gaussian functions were incorporated into integrating algorithms used by an open-source, cross-platform tool called CycloBranch. The quantitation is demonstrated on bacterial pyoverdines separated by fine isotope features. Using our algorithm, we can separate the m/z values 694.25802 and 694.26731 (a 0.009 Da difference), where the former belongs to the most intense peak of pyoverdine D (PvdD), and the latter to the second most intense peak of pyoverdine E (PvdE) in the respective isotopic clusters of [M + Fe-H]2+ ions. The areas under chromatographic curves of standards were analyzed for the limit of detection (LOD), limit of quantitation (LOQ), and regression coefficient calculations. The quantitative module returned a LOD and LOQ of 1.4 and 4.3 ng/mL, respectively, for both PvdD and PvdE in human urine. If present and detected in mass spectra, the intensities of user-defined [M + H]+, [M + Na]+, [M + K]+, [M + Fe-H]2+, or other ion types, can be accumulated and used for quantitation. The quantitation result is returned by CycloBranch in seconds or minutes, contrary to an hours-long manual approach, prone to user-born errors originating from necessary copying among various software environments. Native Bruker, Waters, Thermo, txt, mgf, mzML, and mzXML data formats are supported in CycloBranch, which is freely available at https://ms.biomed.cas.cz/cyclobranch .

The application of continuous flow–extractive desorption electrospray ionization (CF-EDESI), an ambient ionization source demonstrated previously for use with intact protein analysis, is expanded here for the coupling of reversed phase protein separations to mass spectrometry. This configuration allows the introduction of charging additives to enhance detection without affecting the chromatographic separation mechanism. Two demonstrations of the advantages of CF-EDESI are presented in this work. First, a proof-of-principle is presented to demonstrate the applicability of hyphenation of liquid chromatography (LC) to CF-EDESI. LC-CF-EDESI-MS has good sensitivity compared to LC–electrospray ionization (ESI)–mass spectrometry. Second, the supercharging mechanism investigated in CF-EDESI provides an insight into a highly debated supercharging process in ESI. The results indicate that the mechanism of protein charging seen in HPLC-CF-EDESI is different from supercharging phenomena in conventional ESI. The surface tension mechanism and binding mechanism may both contribute to protein supercharging in ESI.

Two nanostructured surfaces are introduced as advantageous substrates for desorption electrospray ionization mass spectrometry (DESI-MS). Nano-assisted laser desorption/ionization (NALDI) plates coated with silicon nanowires (SiNWs) and indium tin oxide (ITO) layers on glass are both conductive non-polar surfaces that were originally designed as superior substrates for matrix-free laser desorption ionization. In this study, NALDI/SiNWs and ITO were tested as potentially useful DESI substrates for selected model analytes (cyclosporine, beauverolide, surfactin and nystatin). Both nanostructured surfaces produced more intense and longer-lasting signals than other tested surfaces (polytetrafluoroethylene, glass, polymethylmethacrylate and chromatography paper).

A home-made nano-desorption electrospray ionization (nano-DESI) device and the kinetic method were tested in chiral analysis of model clinical samples containing enantiomers of one of three pharmaceutically important compounds: dihydroxyphenylalanine (DOPA), ephedrine and ibuprofen. The initial evaluation of chiral systems was carried out by direct infusion of solution mixtures (analyte/central metal/chiral reference ligand) to a standard electrospray ionization (ESI) source. Cu(II) was used as a central metal for all analytes, l-phenylalanine was applied as a chiral reference ligand for DOPA, whereas l-tryptophan was used for the other two analytes. Then, the ESI source was substituted by a nano-DESI source and dried spots of 1 μL samples of whole human blood spiked with individual drugs were successfully analyzed without any pre-treatment. Irrespective of a laborious initial nano-DESI set-up, the combination of the kinetic method with nano-desorption electrospray has, for the first time, been demonstrated as a promising tool for chiral analysis of drugs in blood samples.

High-performance liquid chromatography and tandem mass spectrometry (HPLC/MS/MS) was used for the detection of cyclic hexadepsipeptides roseotoxins produced by Trichothecium roseum. Roseotoxins were found in both submerged standard cultivation on Czapek–Dox medium and in vivo cultivation extract obtained from an apple. Roseotoxin chromatographic profiles from these two experiments were compared. Product-ion collision-induced dissociation (CID) spectra obtained on an ion trap (electrospray ionisation, ESI) were used for the identification of natural roseotoxins A, B, C and of minor destruxins A and B. The dissociation behavior of roseotoxins is discussed in terms of a fragmentation scheme proposed for describing the dissociation pathways of cyclic peptides. This scheme involves opening of the cyclopeptide ring via formation of oxazolone derivatives and fragmentation of the resulting linear species, which have a free N-terminus and an oxazolone ring at the C-terminus. Some aspects of this fragmentation scheme are underlined by modeling the dissociation channels of roseotoxin A using quantum chemical calculations. The structures of roseotoxin A and destruxin B were verified by nuclear magnetic resonance (NMR) spectroscopy. Structures of three new minor natural roseotoxins [Val4]RosA, [MeLxx4]RosA and [MeLxx4]RosB were deduced by ion cyclotron resonance Fourier transform mass spectrometry (ICR-FT-MS) and ion trap tandem mass spectrometry by examining the pre-separated roseotoxin fraction.

It is hard to believe, and yet it is the solemn truth: Vladimir Hanus is seventy-five. This is doubly hard to believe for his co-workers at the Jaroslav Heyrovský Institute of Physical Chemistry and Electrochemistry, Academy of Sciences of the Czech Republic, for whom seeing Dr Hanus in his Prague laboratory has been one of the immutable facts of life for over forty years. It is very rare indeed to find a man of seventy five for whom spending the whole day amidst his instruments in the laboratory is absolutely normal, who relentlessly seeks the right interpretation of his newest results and keeps coming up with brand new, brilliant solutions and ideas. I met Dr Vladimir Hanus for the first time in September 1990 at a Summer School of Mass Spectrometry organised by Dr Miroslav Ryska, the then head of the Czech Society for Mass Spectrometry. The school was intended as an “eye opener” for the run-of-the-mill users of mostly bench-top mass spectrometers. In addition to domestic specialists, Dr Ryska also invited a number of foreign experts whose lectures left me, a fresh graduate of the Prague Institute of Chemical Technology, dazzled and speechless. I remember well how I goggled at the immense protein sequences that nearly spilled over from the transparencies presented by Professor Przybylski, or the then state-of-the-art applications of combined mass spectrometry techniques shown by Dr A.P. Bruins and Professor E. Gelpi. Then Vladimir Hanus took the floor to give his fundamental lecture on doubly-charged ions (of which the School proceedings contained just a two-sentence abstract—why, everybody is naturally assumed to know the chemistry of multiply charged ions!). As the lecture went on, I could see the undisguised admiration in the eyes of even these renowned participants. I realised that this man can speak about virtually anything in the field of organic mass spectrometry and he will always deliver an in-depth scholarly rendering of the problem. A year and a half later I came to Vladimir Hanus to ask him to review my first manuscript that I intended to publish in Organic Mass Spectrometry. I then had the opportunity to know his natural kindness, his ability to rejoice over each piece of good work and his flying into temper over stupidity and mediocrity that hindered creative work. I do not remember how many times I had to rewrite the manuscript; what I gained in the process was the certainty that, if a paper passed

Collision-induced dissociation (CID) mass spectra of selected diagnostic ions generated by electron ionization of a series of natural ergopeptines have been studied in order to develop a general pr...

A series of methylgalactotrioses, in which one or two residues were specifically deoxygenated and labeled with a fluorine atom in the C-3 position, were used as models for the study of “internal residue loss” (IRL) under the conditions of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and electrospray ionization (ESI) techniques. Under the conditions of measurement of MALDI-TOF post-source decay and ESI in-source decay of methyl oligosaccharides, the IRL rearrangement of [M + Na]+ ions did not take place.