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- 2016 (11) (entfernen)
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- Chemometrics (3)
- Hydroformylierung (2)
- Online (2)
- Partial least squares regression (2)
- Raman spectroscopy (2)
- 19F-NMR (1)
- 1H-NMR (1)
- Automation (1)
- Carbamazepine (1)
- Characterization of catalysts (1)
Eingeladener Vortrag
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Der Einsatz moderner Prozessanalysentechnik führt zu einer Datenflut, deren Verarbeitung und Nutzung häufig nicht ohne den Einsatz von Chemometrie zu realisieren ist. Dafür stehen zahlreiche multivariate Verfahren, wie z.B. Hauptkomponentenanalyse (PCA) und Regressionsanalyse (PLSR) für die Klassifizierung und für die quantitative Analyse zur Verfügung. Darüber hinaus können in Spezialfällen, insbesondere in der Spektroskopie, Methoden des „Indirect Hard Modeling“ eingesetzt werden. Anhand einer Industrie-relevanten Reaktion, der Hydroformylierungsreaktion zur Bildung langkettiger Aldehyde aus der Reaktion von Alkenen und Synthesegas, die sowohl im Labormaßstab als auch in einer Miniplant in Kooperation mit der TU Berlin untersucht wurde, werden Kalibrationsstrategien (Design of Experiment, DoE) und Auswertungsansätze mittels PLSR prozessbegleitender Raman Spektren dargelegt. Auf Grundlage des chemometrischen Ansatzes ist eine on-line Überwachung der Reaktion hinsichtlich der Hauptreaktanden, 1-Dodecene und 1-Tridecanal, möglich. Weiterhin konnte mittels Raman Spektroskopie die Bildung eines unerwünschten Nebenprodukts nachgewiesen werden.
Nitroaromaten und insbesondere Trinitrotoluol (TNT) sind weit verbreitete Spreng- und Umweltschadstoffe. Die größte Herausforderung bei der Detektion von TNT in der Gasphase ist der geringe Dampfdruck. Derzeit werden vielerorts günstige, schnelle, handliche und einfach zu bedienende Alternativen zur klassischen TNT-Analytik entwickelt. Aktuell existieren keine einheitlichen Richtlinien für Sprengstoffsensoren. Hier wird die Entwicklung eines Messplatzes zur Validierung von Sprengstoffsensoren sowie die Erprobung eines kompakten Mustersensors vorgestellt.
Due to the increasing presence of microplastic particles (MP) in the Environment and the unknown risks arising from them, there is an urgent need for analytical methods that allow for an efficient identification and quantification of microplastics (MP), i.e. particles < 5 mm, in environmental samples. So far, mostly timeconsuming (micro) infrared or micro-Raman spectroscopic methods are applied. Here an faster alternative Approach is presented based on a Raman processspectrometer with fiber-optical probes in combination with multivariate data analysis.
There is a high demand of monitoring in the era of QbD in industrial scale require new approaches to gain data rapidly and of sufficient quality in real time. Raman spectroscopy technology has great potential but not yet shown it fully in process on-line monitoring due to limitations such as i) uncomplete separation between cells and growth media alone, ii) general weak Raman signals of analytes in complex solutions and iii) strong background signals such as the auto-fluorescence, cosmic rays and surrounding lights overlapping the weak Raman signals. Here we demonstrate a Proof-of-Concept on an the example lactic acid bacteria process using a Streptococcus thermophiles fermentation. Results from three different Raman approaches are presented: 1) Time-Gated Raman Spectroscopy (TG-Raman), 2) Surface Enhanced Raman Spectroscopy (SERS) and 3) Raman process spectroscopy with NIR excitation combined with multivariate data analysis (MVDA) using Principal Component Analysis (PCA) and Partial Least Squares Regression (PLSR).
Abstract. Biodiesel quality control is a relevant issue as biodiesel properties influence diesel engine performance and integrity. Within the European Metrology Research Program (EMRP) ENG09 project “Metrology for Biofuels”, an on-line /at-site suitable near-infrared spectroscopy (NIRS) method has been developed in parallel with an improved EN14110 headspace GC analysis method for methanol in biodiesel. Both methods have been optimized for a methanol content of 0.2 mass% as this represents the maximum limit of methanol content in FAME according to EN 14214:2009. The NIRS method is based on a mobile NIR spectrometer equipped with a fiber-optic coupled probe. Due to the high volatility of methanol, a tailored air-tight adaptor was constructed to prevent methanol evaporation during measurement. The methanol content of biodiesel was determined from evaluation of NIRS spectra by Partial Least Squares Regression (PLS). Both GC analysis and NIRS exhibited a significant dependence on biodiesel feedstock. The NIRS method is applicable to a content range of 0.1 % (m/m) to 0.4 % (m/m) of methanol with uncertainties at around 6% relative for the different feedstocks. A direct comparison of headspace GC and NIRS for samples of FAMEs yielded that the results of both methods are fully compatible within their stated uncertainties.
Two iron-based molten salts comprising an imidazolium and Schiff base were evaluated as catalysts for removal of carbamazepine (CBZ) from water. The catalysts were fully characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), nuclear magnetic resonance spectroscopy (NMR), electrospray ionisation–mass spectrometry (ESI–MS), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption–desorption isotherms (BET). Additionally, the formation of photo-sensitized oxygen was investigated by spin-trapping using electron spin resonance (ESR). The catalytic activity in heterogeneous oxidation of the micropollutant (CBZ) was also evaluated. The effects of catalyst loading, pH, H2O2 dosage and UV light on the oxidation of the selected compound were investigated. After 15 min of UVA irradiation in the presence of 200 μM H2O2, CBZ was completely removed over both catalysts.
Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and processmonitoring. In contrast to high-resolution onlineNMR (HR-NMR),MR-NMRcan be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture fromthe reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by 1H HR-NMR (500MHz) and 1H and 19F MRNMR (43MHz) as amodel system. The parallel online measurement is realised by splitting the flow,which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for 1H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment.
Supernatants from a fermentation process of Pichia pastoris were investigated by Raman spectroscopy. Using partial least squares regression, the principal substrates glycerol and methanol could be predicted, however not the expressed protein. To gain further insight, a priori prepared calibration samples were studied by vibrational-, UV/Vis-, and fluorescence spectroscopy. For the quantification of glycerol and methanol, Raman spectroscopy was identified as the most sensitive technique, and superior to near-infrared spectroscopy, but not for protein contents below 1 g L–1. Both UV/Vis absorption and fluorescence spectroscopy are well suited for the quantification of protein, however, best results were obtained with UV/Vis absorption.
Ugly Spectra and Lousy interfaces – Challenges for Compact NMR Spectroscopy in Process Control
(2016)
With the introduction of advanced process analytical technology, the closeness of key process variables to their limits can be directly controlled and the product can be classified or even released in real time.
Compact NMR instruments can make NMR spectroscopy accessible in industrial and harsh environments for process control.
Homogen katalysierte Reaktionen sind wichtige Werkzeuge der chemischen Industrie. Milde Reaktionsbedingungen und hohe Selektivitäten führen zu einer energie- und ressourcenschonenden Produktion. Ein bedeutender Prozessschritt ist die Hydroformylierung. Hier kommen Kobalt- und Rhodiumkomplexe mit mehrzähnigen Liganden zum Einsatz, die zumeist in wässriger Lösung vorliegen. Die Anwendbarkeit beschränkt sich demnach auf kurzkettige Edukte mit hinreichender Wasserlöslichkeit.