TY - JOUR A1 - Schmid, Thomas A1 - Jungnickel, R. A1 - Neuhaus, B. A1 - Riedel, Jens A1 - Kneipp, Janina A1 - Lüter, C. T1 - Raman spectroscopy as a tool for the collection management of microscope slides N2 - Throughout the history of preparation of biological samples for microscopy the choice of the mounting medium was sometimes dictated merely by availability of the used media. Thus, a plethora of resins and other organic polymers as well as complex mixtures are found to serve as mounting agents in microscope slide collections of museums of natural history, impeding the work for both curators and conservators. Dramatically, in some cases the used mounting media can already be observed to have undergone crystallization and other decomposition processes within few years of mounting demanding immediate action in restoring as well as an imminent precaution in conservation. Therefore, an unambiguous chemical identification of the used agent as well as its current aging stage is of great interest for the biologist community. The technical demands on the analytical approach to obtain this information can be straightforwardly identified. Any used technique has to be non-destructive, yield in molecular information allowing for a chemical identification of the used mounting agents and allow for a spatially well-defined interrogation in a thin sample slice, typically through a transparent cover slip. In this contribution we present a thorough study of the applicability of Raman spectroscopy for the described task. The obtained results clearly demonstrate the successful feasibility of the chosen method for a) a clear distinction between different media, b) the elucidation of the chemical composition of a multicomponent medium and c) an unambiguous identification of real unknown samples by a distinct assignment to a previously recorded spectral library. This library database was built up by recording pure mounting agents and will be provided to the general public. In combination with a Raman spectrometer, it can be an invaluable tool for future curation and conservation endeavors devoted to microscope slide collections at natural history museums. KW - Taxonomy KW - Mounting medium KW - Coverslip seal PY - 2016 DO - https://doi.org/10.1016/j.jcz.2016.07.002 SN - 0044-5231 VL - 265 SP - 178 EP - 190 PB - Elsevier AN - OPUS4-38210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Villatoro, J. A1 - Zühlke, M. A1 - Riebe, D. A1 - Beitz, T. A1 - Weber, M. A1 - Riedel, Jens A1 - Löhmannsröben, H.-G. T1 - IR-MALDI ion mobility spectrometry: physical source characterization and application as HPLC detector N2 - Infraredmatrix-assisted laser dispersion and ionization(IR-MALDI) in combination with on mobility (IM) spectrometry enables the direct Analysis of biomolecules in aqueous solution. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the Absorption of an IR laser pulse, which disperses the liquid as vapor, nano- and micro-droplets. The ionization process is characterized initially by a broad spatial distribution of the ions, which is a result of complex fluid dynamics and desolvation kinetics. These processes have a profound effect on the shape and width of the peaks in the IM spectra. In this work, the Transport of ions by the phase explosion-induced shockwave could be studied independently from the transport by the electric field. The shockwave-induced mean velocities of the ions at different time scales were determined through IM spectrometry and shadowgraphy. The results show a deceleration of the Ions from 118m∙s−1 at a distance of 400 μm from the liquid surface to 7.1 m∙s−1 at a distance of 10 mm, which is caused by a pileup effect. Furthermore, the desolvation kinetics were investigated and a first-order desolvation constant of 325 ± 50 s−1 was obtained. In the second part, the IR-MALDI-IM spectrometer is used as an HPLC detector for the twodimensional separation of a pesticide mixture. KW - Ion mobility spectrometry KW - IR-MALDI KW - Shadowgraphy KW - Laser PY - 2016 DO - https://doi.org/10.1007/s12127-016-0208-1 VL - 2016 IS - 4 SP - 197 EP - 207 PB - Springer-Verlag Berlin CY - Heidelberg AN - OPUS4-38467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bierstedt, Andreas A1 - Riedel, Jens T1 - High-repetition rate laser ablation coupled to dielectric barrier discharge postionization for ambient mass spectrometry N2 - Most ambient sample introduction and ionization techniques for native mass spectrometry are highly selective for polar agents. To achieve a more general sensitivity for a wider range of target analytes, a novel laser ablation dielectric barrier discharge (LA DBD) ionization scheme was developed. The Approach employs a two-step mechanism with subsequent sample desorption and post-ionization. Effective Ablation was achieved by the second harmonic output (λ = 532 nm) of a diode pumped Nd:YVO₄ laser operating at a high-repetition rate of several kHz and pulse energies below 100 μJ. The ejected analytecontaining aerosol was consecutively vaporized and ionized in the afterglow of a DBD plasma jet. Depending on their proton affinity the superexcited Helium species in this afterglow produced analyte ions as protonated and ammoniated species, as well as radical cations. The optimization procedure could corroborate underlying conceptual consideration on the ablation, desorption and ionization mechanisms. A successful detection of a variety of target molecules could be shown from the pharmaceutical ibuprofen, urea, the amino acids L-arginine, L-lysine, the polymer polyethylene glycol, the organometallic compound ferrocene and the technical mixture wild mint oil. For a reliable evaluation of the introduced detection procedure spectra from the naturally abundant alkaloid capsaicin in dried capsicum fruits were recorded. KW - Laser ablation KW - High-repetition rate laser KW - Dielectric barrier discharge KW - Ambient mass spectrometry PY - 2016 DO - https://doi.org/10.1016/j.ymeth.2016.02.002 SN - 1046-2023 IS - 104 SP - 3 EP - 10 PB - Elsevier CY - Oxford AN - OPUS4-36730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Villatoro, J. A1 - Zühlke, M. A1 - Riebe, D. A1 - Riedel, Jens A1 - Beitz, T. A1 - Löhmannsröben, H.-G. T1 - IR-MALDI ion mobility spectrometry N2 - The novel combination of infrared matrix-assisted laser dispersion and inization (IR-MALDI) with ion mobility (IM) spectrometry makes it possible to investigate biomolecules in their natural environment, liquid water. As an alternative to an ESI source, the IR-MALDI source was implemented in an in-house-developed ion mobility (IM) spectrometer. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse (λ = 2.94 μm, 6 ns pulse width), which disperses the liquid as nano- and micro-droplets. The prerequisites for the application of IR-MALDI-IM spectrometry as an analytical method are narrow analyte ion signal peaks for a high spectrometer resolution. This can only be achieved by improving the desolvation of ions. One way to full desolvation is to give the cluster ions sufficient time to desolvate. Two methods for achieving this are studied: the implementation of an additional drift tube, as in ESI-IM-spectrometry, and the delayed extraction of the ions. As a result of this optimization procedure, limits of detection between 5 nM and 2.5 μMas well as linear dynamic ranges of 2–3 orders of magnitude were obtained for a number of substances. The ability of this method to analyze simple mixtures is illustrated by the separation of two different surfactant mixtures. KW - Ion mobility KW - Spectrometry KW - IR-MALDI KW - Laser PY - 2016 DO - https://doi.org/10.1007/s00216-016-9739-x SN - 1618-2650 SN - 1618-2642 VL - 408 IS - 23 SP - 6259 EP - 6268 PB - Springer-Verlag CY - Heidelberg AN - OPUS4-37615 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bierstedt, Andreas A1 - Riedel, Jens T1 - Airborne laser-spark for ambient desorption/ionisation N2 - 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. N2 - 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 freigesetzt werden, welche sich konzentrisch ausbreiten, so dass eine Diffusion der Analytmoleküle ins heiße Innere des Plasmas verhindert wird. Daraus folgt, dass im Interaktionsvolumen zwischen Plasma und Analyt der Temperaturgrenzwert für eine thermische Dissoziation oder Fragmentierung der Moleküle nicht überschritten wird. Experimentell konnte belegt werden, dass das vorgestellte Ionisierungsschema sehr unselektiv bezüglich der chemischen Analytklasse ist und kaum Fragmentierungsprodukte beobachtet werden können. Messungen einer breitgefächerten Auswahl unterschiedlicher Testsubstanzen, wie beispielsweise polarer und unpolarer Kohlenwasserstoffe, Zuckern, niedermolekularer pharmazeutischer Wirkstoffe, sowie natürlicher Biomoleküle in Lebensmittelproben unmittelbar aus ihren komplexen Matrizes, führten zu aussagekräftigen Massenspektren. Zumal das Lasermedium feuchte Luft ist, scheint der Reaktionsmechanismus dem anderer Atmosphärendruckionisierungsmethoden zuähneln. KW - Laser-spark KW - Laser-induced plasma KW - DPSS laser KW - High repetition rate KW - Ambient mass spectrometry KW - Time-of-flight mass spectrometry KW - Ionisation PY - 2016 DO - https://doi.org/10.1255/ejms.1417 SN - 1469-0667 VL - 22 IS - 3 SP - 105 EP - 114 PB - IM Publications LLP CY - Chichester, UK AN - OPUS4-37286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kern, Simon A1 - Michalik-Onichimowska, Aleksandra A1 - Riedel, Jens A1 - Panne, Ulrich A1 - King, Rudibert A1 - Maiwald, Michael ED - Maiwald, Michael T1 - “Click” analytics for “click” chemistry – a simple method for calibration-free evaluation of online NMR spectra N2 - Currently research in chemical manufacturing moves towards flexible plug-and-play approaches focusing on modular plants, capable of producing small scales on-demand with short down-times between individual cam-paigns. This approach allows for efficient use of hardware, a faster optimization of the process conditions, and thus, an accelerated introduction of new products to the market. Driven mostly by the search for chemical syntheses under biocompatible conditions, so-called “click” chemistry rapidly became a growing field of research. The re-sulting simple one-pot reactions are so far only scarcely accompanied by an adequate optimization via compara-bly straightforward and robust analysis techniques. Here we report on a fast and reliable calibration-free online high field NMR monitoring approach for technical mixtures. It combines a versatile fluidic system, continuous-flow measurement with a time interval of 20 s per spectrum, and a robust, automated algo-rithm to interpret the ob-tained data. All spectra were acquired using a 500 MHz NMR spectrometer (Varian) with a dual band flow probe having a 1/16 inch polymer tubing working as a flow cell. Single scan 1H spectra were recorded with an acquisition time of 5 s, relaxation delay of 15 s. T2 - 12. Kolloquium des Arbeitskreises Prozessanalytik CY - Berlin, Germany DA - 28.11.2016 KW - “Click” chemistry KW - Online NMR KW - Online monitoring PY - 2016 SP - 72 EP - 74 AN - OPUS4-38385 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -