24 research outputs found
Development of Methods for the Analysis of N-Acylhomoserine Lactones by Capillary Separation Techniques and Mass Spectrometry
No full textN-Acyl-Homoserinlactone (AHL, HSL) spielen eine zentrale Rolle als Semiochemikalien bei der zelldichteabhängigen Kommunikation von Bakterien (Quorum Sensing, QS). Ungeachtet der weitreichenden Bedeutung des QS im medizinischen, landwirtschaftlich-ökonomischen und ökologischen Bereich erschien die Bandbreite der verfügbaren Nachweismethoden für HSL eingeschränkt. In der vorliegenden Arbeit werden unabhängige Strategien zur Analyse von HSL durch massenspektrometriegekoppelte Kapillartrenntechniken (micellare elektrokinetische Chromatographie, miniaturisierte Flüssigkeitschromatographie, Kapillarzonenelektrophorese, Gaschromatographie) in Verbindung mit spezifischen Aufkonzentrierungs- und Extraktionstechniken sowie durch ultrahochauflösende Fourier-Transform-Ionencyclotron-Resonanz-Massenspektrometrie vorgestellt. Durch Realprobenmessungen wird die Eignung der entwickelten Methoden für unterschiedliche Fragestellungen demonstriert.N-acylhomoserine lactones play a central role as semiochemicals in cell-density dependent communication phenomena in bacteria (quorum sensing, QS). Despite the high relevance of QS processes in medical, agricultural, economic and ecological contexts, the bandwidth of available methods for HSL detection and quantification was limited. In this work, independent strategies for the analysis of HSL by mass spectrometry-coupled capillary separation techniques (micellar electrokinetic chromatography, miniaturized liquid chromatography, capillary zone electrophoresis, gas chromatography) in connection with specific preconcentration and extraction methods and by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry are presented. The applicability of the methods for specific questions is demonstrated by real sample measurements
Capillary electrophoresis – mass spectrometry: 15 years of developments and applications
No full textTactile Feedback for Artery Detection in Minimally Invasive Robotic Surgery –Preliminary Results of a New Approach
No full textMinimally invasive robotic surgery (MIRS) entails
total absence of haptic feedback due to the spatial separation
of patient and surgeon. In conventional surgery, however,
palpation to detect superficial arteries by a slight pulsation is
an important, commonly applied, and security-relevant procedure.
Therefore, an ultrasound based unidirectional sensor for
MIRS was developed feeding back kinesthetic impulses to the
surgeon-sided haptic input device
Practical considerations for the analysis of ionic and neutral organic molecules with capillary electrophoresis/mass spectrometry.
No full textThis chapter presents the technique of capillary electrophoresis coupled to mass spectrometry (CE/MS). The introductory section is targeted mainly at CE/MS beginners and notes briefly the theoretical background of electrospray ionization (ESI), the most commonly used ionization mode in CE/MS. The specifics of CE/MS are described—also in comparison with more classic methods like LC/MS. Important caveats to be taken nto consideration for successful CE/MS operation are noted in the interest of avoiding pitfalls. CE/MS is illustrated with three representative examples, which might serve as starting points for more in-detail experiments: (1) partial-filling micellar elektrokinetic chromatography (MEKC) ofneutral bacterial signaling molecules (N-acylhomoserine lactones) extracted from culture supernatants, (2) capillary zone electrophoresis (CZE) of their anionic degradation products, and finally (3) CZE separation of cationic hydroxys-triazines
Metabolomics: High‐resolution tools offer to follow bacterial growth on a molecular level.
No full text‐acylhomoserine lactones after alkaline hydrolysis and anion‐exchange solid‐phase extraction by capillary zone electrophoresis‐mass spectrometry
No full text
Characterization of a major refractory component of marine dissolved organic matter.
No full textAbstract Refractory carboxyl-rich alicyclic molecules (CRAM) are characterized in marine dissolved organic matter (DOM) using nuclear magnetic resonance spectroscopy and ultrahigh resolution mass spectrometry. CRAM are distributed throughout the water column and are the most abundant components of deep ocean DOM ever characterized. CRAM are comprised of a complex mixture of carboxylated and fused alicyclic structures with a carboxyl-C:aliphatic-C ratio of 1:2 to 1:7. CRAM are expected to constitute a strong ligand for metal binding, and multiple coordination across cations could promote aggregation and marine gel formation thereby affecting CRAM reactivity and the bioavailability of nutrients and trace metals. It appears CRAM are ultimately derived from biomolecules with structural similarities to sterols and hopanoids. The occurrence of CRAM in freshwater and terrestrial environments seems likely, considering the global distribution of biomolecules and the similarities of biogeochemical processes among environments
A new sesquiterpene lactone sulfate from Reichardia gaditana (Asteraceae).
No full textThe new sesquiterpenoid 8-deoxy-15-(3'-hydroxy-2'-methyl-propanoyl)-lactucin 3'-sulfate (1) was isolated from the methanolic extract of roots of Reichardia gaditana L. The compound was isolated by silica gel column chromatography (CC) and repeated Sephadex LH-20 CC. Structure elucidation was accomplished by high-resolution mass spectrometry and by 1D- and 2D-NMR spectroscopy. The chemosystematic significance of the new compound is discussed in the context of sesquiterpenoids from other members of the Lactuceae tribe of the Asteraceae family
