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Die immer stärker alternde Gesellschaft und der erhöhte Konsum von zuckerhaltigen Nahrungsmitteln sorgt für eine stetig steigende Anzahl an Diabetes mellitus Typ 2 Erkrankten. Zur Behandlung wird häufig der Wirkstoff Metformin verwendet, welcher die Neubildung von Glucose in der Leber hemmt. Neben den steigenden Patientenzahlen sind auch die hohen Mengen an wieder ausgeschiedenem Metformin mit großer Sorge zu beobachten. Metformin kann durch Förderung der Glukoseaufnahme und des Katabolismus in den Steroidstoffwechsel eingreifen und das endokrine System von Wirbeltieren wie Fischen und Säugetieren beeinflussen. Die Kontrolle von Abwasser-Grenzwerten ist bei Metformin bislang noch sehr aufwendig und teuer.
Das Ziel dieser Arbeit ist, einen Dünnschichtchromatographie Assay zu entwickeln mit dem Metformin anhand von Fluoreszenz nachgewiesen werden kann. Voraussetzung ist, dass eine Reproduzierbarkeit mit gängigen Laborutensilien gegeben und ein Nachweis von Metformin in einer Abwasserprobe grundsätzlich möglich ist. Ein solcher Assay würde den Kosten- und Zeitaufwand reduzieren und gleichzeitig eine zuverlässige und regelmäßige Überprüfung von Abwässern ermöglichen.
Es konnte ein Assay entwickelt werden, mit dem ein reproduzierbarer Nachweis von Metformin in Wasser möglich ist. Für eine Bewertung des Metformin-Gehaltes in unbehandelten Abwasserproben innerhalb des Grenzwertes konnte allerdings noch nicht die benötigte Sensitivität erreicht werden. Die Versuche mit DTT eine Verbesserung der Sensitivität zu erreichen, geben allerdings eine vielversprechende Aussicht auf eine weitere Möglichkeit den Assay zu verbessern. Die Umsetzbarkeit eine Abwasserproben mittels SPE vor dem Anwenden des Assays zu konzentrieren konnte belegt werden. Qualitativ ist der Assay somit grundsätzlich anwendbar. Voraussetzung hierfür ist ein ausreichendes Konzentrieren der Proben. Eine Nutzung zur quantitativen Bewertung hingegen kann durch eine schlechte Ausbeute an Analyt verfälscht werden und hängt somit stark von der Effizienz der SPE ab.
The research employed HPTLC Pro System and other HPTLC instruments from CAMAG® to conduct various laboratory tests, aiming to compile a database for subsequent analyses. Utilizing MATLAB, distinct codes were developed to reveal patterns within analyzed biomasses and pyrolysis oils (sewage sludge, fermentation residue, paper sludge, and wood). Through meticulous visual and numerical analysis, shared characteristics among different biomasses and their respective pyrolysis oils were revealed, showcasing close similarities within each category. Notably, minimal disparity was observed in fermentation residue and wood biomasses with a similarity coefficient of 0.22. Similarly, for pyrolysis oils, the minimal disparity was found in fermentation residues 1 and 3, with a disparity coefficient of 1.41. Despite higher disparity coefficients in certain results, specific biomasses and pyrolysis oils, such as fermentation residue and sewage sludge, exhibited close similarities, with disparity coefficients of 0.18 and 0.55, respectively. The database, derived from triplicate experimentation, now serves as a valuable resource for rapid analysis of newly acquired raw materials. Additionally, the utility of HPTLC PRO as an investigation tool, enabling simultaneous analysis of up to five samples, was emphasized, although areas for improvement in derivatization methods were identified.
Lithium-ion battery cells exhibit a complex and nonlinear coupling of thermal, electrochemical,and mechanical behavior. In order to increase insight into these processes, we report the development of a pseudo-three-dimensional (P3D) thermo-electro-mechanical model of a commercial lithium-ion pouch cell with graphite negative electrode and lithium nickel cobalt aluminum oxide/lithium cobalt oxide blend positive electrode. Nonlinear molar volumes of the active materials as function of lithium stoichiometry are taken from literature and implemented into the open-source software Cantera for convenient coupling to battery simulation codes. The model is parameterized and validated using electrical, thermal and thickness measurements over a wide range of C-rates from 0.05 C to 10 C. The combined experimental and simulated analyses show that thickness change during cycling is dominated by intercalation-induced swelling of graphite, while swelling of the two blend components partially cancel each other. At C-rates above 2 C, electrochemistry-induced temperature increase significantly contributes to cell swelling due to thermal expansion. The thickness changes are nonlinearly distributed over the thickness of the electrode pair due to gradients in the local lithiation, which may accelerate local degradation. Remaining discrepancies between simulation and experiment at high C-rates might be attributed to lithium plating, which is not considered in the model at present.
In order to make material design processes more efficient in the future, the underlying multidimensional process parameter spaces must be systematically explored using digitalisation techniques such as machine learning (ML) and digital simulation. In this paper we shortly review essential concepts for the digitalisation of electrodeposition processes with a special focus on chromium plating from trivalent electrolytes.
A simple method for quantifying triazine herbicides using thin-layer chromatography and a ccd camera
(2010)
We present a video-densitometric quantification method for the triazine herbicides atraton, terbumeton, simazine, atrazine, and terbutylazine. Triazine herbicides were separated on silica gel using methyl-t-butyl ether, cyclohexane (1 + 1, v/v) as mobile phase. The quantification is based on a derivation reaction using chlorine and starch-iodine which forms red-brown triazine zones. Measurements were carried out using a 16 bit ST-1603ME CCD camera with 1.56 megapixel from Santa Barbara Instrument Group, Inc., Santa Barbara, USA. A white LED was used for illumination purposes. The range of linearity covers two magnitudes using the (1/R-1) expression data transformation. The signal-to-noise ratio increases directly linearly with the measurement time. The separation method is cheap, fast and reliable.
Wir präsentieren die weltweit erste Auswertung einer zweidimensional entwickelten HPTLC-Platte (2D-HPTLC) mit Hilfe eines Diodenarray Scanners. Das System erreicht eine räumliche Plattenauflösung von 250 µm. Es können Absorptions- und Fluoreszenzspektren im Wellenlängenbereich von 190 bis 1000 nm mit einer spektralen Auflösung von besser als 1 nm gemessen werden. Eine Trennzahl von 259 wurde erreicht. Damit zeigt die Methode bessere Trenneigenschaften als die meisten HPLC-Systeme. Der Nachteil der 2D-Auswertung ist der hohe Zeitbedarf von über 3 Stunden für eine Plattenmessung.
We present a video-densitometric quantification method for the pain killer known as diclofenac and ibuprofen. These non-steroidal anti-inflammatory drugs were separated on cyanopropyl bonded plates using CH2Cl2, methanol, cyclohexane (95+5+40, v/v) as mobile phase. The quantification is based on a bio-effective-linked analysis using vibrio fischeri bacteria. Within 10 minutes a CCD-camera registers the white light of the light-emitting bacteria. Diclofenac and ibuprofen effectively suppress the bacterial light emission which can be used for quantification within a linear range of 10 to 2000 ng. The detection limit for ibuprofen is 20 ng and the limit of quantification 26 ng per zone. Measurements were carried out using a 16-bit ST-1603ME CCD camera with 1.56 megapixels [from Santa Barbara Instrument Group, Inc., Santa Barbara, USA]. The range of linearity covers more than two magnitudes because the extended Kubelka-Munk expression is used for data transformation [1]. The separation method is inexpensive, fast and reliable. Ibuprofen is named after its chemical description: iso-butyl-propanoic phenolic acid. Both pain killers are world-widein use and both substances are stable in aqueous solution. Both substances are mainly excreted in the urine.
The objective of this thesis is the quantification and qualification of neonicotinoid insecticides using thin-layer chromatography (TLC). Neonicotinoids are a relatively new form of pesticides, which have been proven to be extremely lethal to the honey bee, Apis mellifera. In this paper six forms of neonicotinoid insecticides (i.e. Acetamiprid, Thiacloprid, Imidacloprid, Clothianidin, Thaimethoxam, and Nitenpyram) are analysed. The initial steps are to first find a suitable mobile phase eluent, followed by the search for a reagent causing a luminescence effect of the neonicotinoids on a TLC plate. Subsequently, a calibration method is then used to find the detection limit of this TLC experiment. The aim is, therefore, to achieve a standard method of quantifying and qualifying neonicotinoids via TLC. Whilst a suitable mobile phase has been established, an optimal fluorescent reagent has yet to be found and more research on the subject must be carried out.
A simple Method for quantifying Triazine Herbicides using Thin-Layer Chromatography and a CCD-Camera
(2010)
Modern TLC-scanners can measure in absorption, fluorescence and also in transmittance. TLC-scanners cover the whole wavelength range from 200 up to 1100 nm. The disadvantage of TLC and HPTLC scanners is their high purchase price and maintenance costs. The high price of modern TLC-scanners makes image analysis in thin-layer chromatography (TLC) so interesting. Most TLC-applications are designed to work in the wavelength range from 400 to 800 nm, using human eyes as detectors. Scanning equipment like CCD-cameras (charge coupling device-cameras) or flatbed-scanners working in the visible range are cheaply available and can be used for plate evaluation. The term video-densitometer has also been introduced for such scanning devices.
Melamine (1,3,5-triazine-2,4,6-triamine or cyanuramide, C3H6N6) is a trimer of cyanamide, with a 1,3,5-triazine skeleton (Figure 3.5-1). The molecule contains 66% nitrogen by mass and, if mixed with resins, has fire retardant properties due to its release of nitrogen gas when burned or charred. The word melamine (from German) is a combination of the word melam (which is a distillation derivative of ammonium thiocyanate) and amine [1]. Melamine is also a metabolite of cyromazine, an insecticide in which the proton of an NH2-group is substituted by a cyclopropyl group.