Presence of Chlorinated Paraffins in Sediments from the North and Baltic Seas

Chloroparaffins (CPs) were determined in sediments collected from the North and Baltic Seas during monitoring campaigns in 2001-2003. Electron ionization tandem mass spectrometry (MS/MS) was used for a first screening. It allowed the simultaneous determination of short (SCCP) and medium chain chlorinated paraffins (MCCP). SCCP+MCCP concentrations between 5 and 499 ng/g dry weight were found. In general, Baltic Sea sediments were more highly contaminated by CPs than the North Sea was. However, concentrations related to the total organic carbon content were on the same order of magnitude due to the higher organic content in the Baltic Sea. Additional information about the congener and homologue pattern was obtained for selected samples from the Baltic Sea by high-resolution gas chromatography combined with negative ion chemical ionization and low-resolution mass spectrometry, Concentrations in the North Sea were in general too low for this approach. In the Baltic Sea, MCCP concentrations were 1.7-2.4 times higher than for SCCPs. Lower chlorinated C13 and C14 compounds were the main CP compounds. The CP congener and homologue patterns showed similarities with technical SCCP and MCCP mixtures when compared using principal component analysi

Limitations of low resolution mass spectrometry in the electron capture negative ionization mode for the analysis of short- and medium-chain chlorinated paraffins

The analysis of complex mixtures of chlorinated paraffins (CPs) with short (SCCPs, C10-C13) and medium (MCCPs, C14-C17) chain lengths can be disturbed by mass overlap, if low resolution mass spectrometry (LRMS) in the electron capture negative ionization mode is employed. This is caused by CP congeners with the same nominal mass, but with five carbon atoms more and two chlorine atoms less; for example C11H17 37Cl35Cl6 (m/z395.9) and C16H29 35Cl5 (m/z396.1). This can lead to an overestimation of congener group quantity and/or of total CP concentration. The magnitude of this interference was studied by evaluating the change after mixing a SCCP standard and a MCCP standard 1+1 (S+MCCP mixture) and comparing it to the single standards. A quantification of the less abundant C16 and C17 congeners present in the MCCP standard was not possible due to interference from the major C11 and C12 congeners in the SCCPs. Also, signals for SCCPs (C10-C12) with nine and ten chlorine atoms were mimicked by MCCPs (C15-C17) with seven and eight chlorine atoms (for instance C10H12Cl10 by C15H24Cl8). A similar observation was made for signals from C15-C17 CPs with four and five chlorine atoms resulting from SCCPs (C10-C12) with six and seven chlorine atoms (such as C15H28Cl4 by C10H16Cl6) in the S+MCCP mixture. It could be shown that the quantification of the most abundant congeners (C11-C14) is not affected by any interference. The determination of C10 and C15 congeners is partly disturbed, but this can be detected by investigating isotope ratios, retention time ranges and the shapes of the CP signals. Also, lower chlorinated compounds forming [M+Cl]− as the most abundant ion instead of [M-Cl]− are especially sensitive to systematic errors caused by superposition of ions of different composition and the same nominal mas

Organosulfates - A New Component of Humic-Like Substances in Atmospheric Aerosols?

Ion trap mass spectrometry (ITMS) was used to obtain further qualitative information about the chemical composition of humic-like substances (HULIS) in atmospheric particulate matter. Particles ≤10 μm (PM10) were collected on quartz fiber filters for 24 h in the region of Basel (Switzerland) and extracted with water. HULIS were separated from inorganic salts by size exclusion chromatography (SEC) and detected by electrospray ionization in the negative ion mode (ESI(−)). Series of consecutive fragment ion spectra (MSn) were recorded by ITMS. Full scan mass spectra of the extracts showed a mass distribution pattern characteristic for HULIS. Different molecular ions were selected from this pattern for further fragmentations. Among them the molecular ion m/z 299 was considered as representative and intensively studied. Many MS2 and MS3 fragment spectra contained a fragment m/z 97 and a neutral loss of 80 u. Time-of-flight (TOF) MS and deuterium exchange experiments identified m/z 97 as hydrogen sulfate. MS2 and MS3 fragment spectra supported the existence of sulfate covalently bound to HULIS. The fragmentation behavior of sulfated HULIS could be confirmed by model compound

Structure elucidation of nanogram quantities of unknown designer drugs based on phenylalkylamine derivates by ion trap multiple mass spectrometry

Multiple mass spectra (MS1 to MS6) of 55 phenylalkylamine derivatives were recorded with ion-trap mass spectrometry employing electrospray (ESI) and atmospheric pressure chemical ionization (APCI). Fragmentation patterns were studied in detail and a generally applicable scheme was established for elucidation of the structures of phenylalkylamine derivatives. HPLC combined with ion-trap multiple mass spectrometry was used to identify the structure of reaction by-products in ecstasy samples from the "black” market. Low nanogram amounts were sufficient for on-line HPLC-MS n structure elucidation of unknown

Structure Elucidation and Quantification by HPLC Ion-Trap Multiple Mass Spectrometry

High-performance liquid chromatography combined with ion-trap mass spectrometry allows now to record mass spectra in the full-scan mode with sample quantities around 1 ng or less. In addition, the on-line generation of multiple daughter-ion spectra has become possible. This has revolutionised organic trace analysis. Small polar and/or thermolabile molecules such as biotoxins can be detected in the trace range and their structure unequivocally identified. In addition, a complete or partial structure elucidation of related structures is possible. This overview demonstrates the possibilities and limitations of HPLC-Msn with ion traps. Examples shown are the structure elucidation of aconitum alkaloids, trichothecenes and photochemically formed carbonyl compounds. This survey discusses also problems caused by system contamination and adsorption effects. Finally, the achievable performance of quantification in the trace range is briefly presented

Delineating the conformal window

We identify and characterise the conformal window in gauge theories relevant for beyond the standard model building, e.g. Technicolour, using the criteria of metric confinement and causal analytic couplings, which are known to be consistent with the phase diagram of supersymmetric QCD from Seiberg duality. Using these criteria we find perturbation theory to be consistent throughout the predicted conformal window for several of these gauge theories and we discuss recent lattice results in the light of our findings.Comment: 8 pages, 4 figure

Evidence of Longitudinal Acoustic Phonon Generation in Si Doping Superlattices by Ge Prism-Coupled THz Laser Radiation

We report on the direct excitation of 246 GHz longitudinal acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation of the same frequency. A longitudinally polarized evanescent laser light field is coupled to the superlattice through a germanium prism providing total internal reflection at the superlattice interface. The ballistic phonon signal is detected by a superconducting aluminum bolometer. The sample is immersed in low-temperature liquid helium

Farbexperimente mit RGB-Leuchtdioden

Interessante Farbeffekte treten auf, wenn man durch ein Glasprisma auf Hell-Dunkel- oder Farbstrukturen schaut. In der vorliegenden Arbeit werden Kombinationen aus Spalt und Steg untersucht, um solche Farbeffekte zu hinterfragen. Bei den Experimenten werden RGB-LED-Leuchten eingesetzt, um Spalt- und Stegmasken variabel und homogen mit farbigem Licht auszuleuchten. Dadurch gelingt es, das den Spalt durchsetzende Licht in unterschiedliche Umgebung einzubetten. Mit einem Geradsichtprisma werden Spektren des Spaltlichts, des Umgebungslichts und des Gesamtlichts erzeugt. Ein einfaches RGB-Modell unterstützt die Analyse der Spektren. Selbst zunächst überraschende Farbfelder lassen sich dadurch mit den Gesetzmäßigkeiten der Newtonschen Optik erklären.