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Coupling of Acoustically Levitated Droplets with Ion Mobility Spectrometry

  • Introduction The list of applications for ion mobility spectrometry (IMS) is steadily growing quickened by advances in instrumental design, experimental methods and accompanying theory. The performance of IMS is greatly influenced by the ionization source and the introduction of the analyte, hence new ionization schemes and sampling strategies recently received particular interest.[1] An overall new approach is the coupling of IMS to an acoustically levitated droplet and combined sample desorption/ionization by a laser. In this setup the acoustically levitated droplet works as a wall-less micro reactor.[2] The latter opens the way towards quality control of fast reactions. Generally, the combination of acoustically levitated droplet and IMS bears a wide range of applications from routine analysis to microfluidic optimization of chemical reactions. Experimental part A novel coupling of an acoustically levitated droplet with a homebuilt drift tube ion mobility spectrometry isIntroduction The list of applications for ion mobility spectrometry (IMS) is steadily growing quickened by advances in instrumental design, experimental methods and accompanying theory. The performance of IMS is greatly influenced by the ionization source and the introduction of the analyte, hence new ionization schemes and sampling strategies recently received particular interest.[1] An overall new approach is the coupling of IMS to an acoustically levitated droplet and combined sample desorption/ionization by a laser. In this setup the acoustically levitated droplet works as a wall-less micro reactor.[2] The latter opens the way towards quality control of fast reactions. Generally, the combination of acoustically levitated droplet and IMS bears a wide range of applications from routine analysis to microfluidic optimization of chemical reactions. Experimental part A novel coupling of an acoustically levitated droplet with a homebuilt drift tube ion mobility spectrometry is presented. A new prototype of inlet was customized according to design constrains yielding in maximum ion transmission. Moreover, the commonly used plate repeller was replaced with a point electrode to form a concentric electric field between the droplet and the IMS, geometrically allowing space for the acoustically levitated droplet. The desorption/ionization out of the droplet was performed with an optical parametric oscillator at 2,94 µm wavelength with pulse duration of FWHM = 7 ns. Primary evaluation of the setup was achieved using tetra-n-butylammonium bromide, promazine, perphenazine and L-arginine in direct comparison with the results obtained with a µdroplet IR-MALDI IMS. Results and discussion The coupling of acoustically levitated droplet with IMS was successfully realized giving further possibilities to utilize it as detection method to interrogate the fast kinetics of reactions preformed directly in the droplet. The presented modifications simplify the assembly of the setup and allow for a sufficient isolation between the high voltage, applied on the individual electrodes of the IMS, and the acoustic field sonotrode. The implemented point electrode produces a concentric steep potential field around the acoustically levitated droplet forcing the flow of nascent ions towards the drift tube inlet region. Additionally, it minimizes spatial restrictions giving space for a better accessibility for the sampling laser beam. The recorded ion mobility spectra confirm that the entire arrangement results in an efficient desorption, ionization and ion transfer of the sample liquid. First results show a sensitivity of the IMS comparable to that of the previously introduced µdroplet IR-MALDI. However the main advantage of acoustically levitated droplet is the reduction of long memory effect typically observed for the µdroplet source. These memory effects are attributed to wash-out times of the sample volume and to contamination of surfaces that get into contact with the sample. The contribution can therefore positively demonstrate that by avoiding sample-surface interfaces, the instrument response function can be drastically shortened. This not only significantly decreases the time necessary to clean the system between subsequent measurements but mostly opens the path towards fast kinetic monitoring of chemical reactions within the microdroplet reactors. New aspects The combination of acoustically levitated droplets and ion mobility separation provides a tool for direct online detection of reaction kinetics.zeige mehrzeige weniger

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Metadaten
Autor*innen:Aleksandra Michalik-Onichimowska
Koautor*innen:Jens Riedel, Ulrich Panne
Dokumenttyp:Posterpräsentation
Veröffentlichungsform:Präsentation
Sprache:Deutsch
Titel des übergeordneten Werkes (Deutsch):DGMS 2015
Jahr der Erstveröffentlichung:2015
Veranstaltung:DGMS 2015
Veranstaltungsort:Wuppertal
Beginndatum der Veranstaltung:2015-03-01
Enddatum der Veranstaltung:2015-03-04
Verfügbarkeit des Dokuments:Weder Datei noch physisches Exemplar vorhanden ("No Access")
Datum der Freischaltung:20.02.2016
Referierte Publikation:Nein
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