Atmospheric pressure imaging mass spectrometry of drugs with various ablating lasers

Moshkunov, Konstantin; Alimpiev, S. S.; Grechnikov, A. A.; Nikifirov, S M; Pento, A. V.; Simanovsky, Ya. O.

doi:10.1088/1742-6596/558/1/012012

Cited by 2 publications

(2 citation statements)

References 12 publications

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“…However, this method was found to yield in a relatively poor sensitivity, but could be improved by magnetic confinement and the use of a femtosecond laser . Analysis of organic compounds was demonstrated by the group of Alimpiev and co-workers. , However, plasma ignition on a metal target still introduces disadvantageous reactive metallic species, which could potentially generate chemical interferences and introduce erratic pulse-to-pulse fluctuations, caused by target surface inhomogeneities.…”

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confidence: 99%

Characterization of an Airborne Laser-Spark Ion Source for Ambient Mass Spectrometry

et al. 2017

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An airborne laser plasma is suggested as an ambient ion source for mass spectrometry. Its fundamental physical properties, such as an excellent spatial and temporal definition, high electron and ion densities and a high effective cross section in maintaining the plasma, make it a promising candidate for future applications. For deeper insights into the plasma properties, the optical plasma emission is examined and compared to mass spectra. The results show a seemingly contradictory behavior, since the emitted light reports the plasma to almost entirely consist of hot elemental ions, while the corresponding mass spectra exhibit the formation of intact molecular species. Further experiments, including time-resolved shadowgraphy, spatially resolved mass spectrometry, as well as flow-dependent emission spectroscopy and mass spectrometry, suggest the analyte molecules to be formed in the cold plasma vicinity upon interaction with reactive species formed inside the hot plasma center. Spatial separation is maintained by concentrically expanding pressure waves, inducing a strong unidirectional diffusion. The accompanying rarefaction inside the plasma center can be compensated by a gas stream application. This replenishing results in a strong increase in emission brightness, in local reactive species concentration, and eventually in direct mass spectrometric sensitivity. To determine the analytical performance of the new technique, a comparison with an atmospheric pressure chemical ionization (APCI) source was conducted. Two kitchen herbs, namely, spearmint and basil, were analyzed without any sample pretreatment. The presented results demonstrate a considerably higher sensitivity of the presented laser-spark ionization technique.

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Characterization of an Airborne Laser-Spark Ion Source for Ambient Mass Spectrometry

et al. 2017

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“…22 More recently they reported on an implementation of this technique into the inlet system of a AP-MS system. 23 However, the plasma is still generated on a metal target. Besides the introduction of metallic reactive species that can generate chemical interferences, this approach further introduces undesired pulse to pulse fluctuations caused by subtle differences in the illuminated target surface.…”

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confidence: 99%

Airborne Laser-Spark for Ambient Desorption/Ionisation

Bierstedt

Riedel

2016

Eur J Mass Spectrom (Chichester)

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A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die Desorption als auch die Ionisation erfolgen hierbei durch ein laserbetriebenes Luftplasma. Die Abwesenheit fester oder flüssiger Elektroden hat zur Folge, dass die Methode weder unter chemischen Interferenzen noch unter Verschleiß durch Korrosionsbrand oder abgetragenes Elektrodenmaterial leidet. Insgesamt betrachtet herrscht in dem Plasma Elektroneutralität, wodurch Aufladungseffekte minimiert werden, die andernfalls zu einer langfristigenÄderung der Flugbahnen von Ionen während der Experimente führen kann. In dem Ansatz eine freischwebende Luftentladung bei Atmosphärendruck zu verwenden agiert die Luft nicht nur als Plasmamedium sondert dient zusätzlich als Badgas für die stoßinduzierte Kühlung der entstehenden Ionen. Die Ionisierung der Analytmoleküle erfolgt nicht unmittelbar im Plasma sondern in dessen direkter Umgebung durch Wechselwirkung mit freigesetzten ionischen Luftspezies, freien Elektronen oder Photonen im kurzwelligen ultravioletten Bereich. Jede Laserentladung erzeugt eine hörbare Stoßwelle, in welcher neu produzierte reaktive Spezies freiges...

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Atmospheric pressure imaging mass spectrometry of drugs with various ablating lasers

Cited by 2 publications

References 12 publications

Characterization of an Airborne Laser-Spark Ion Source for Ambient Mass Spectrometry

Characterization of an Airborne Laser-Spark Ion Source for Ambient Mass Spectrometry

Airborne Laser-Spark for Ambient Desorption/Ionisation

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