Mixtures of 12 known volatile metabolites of Escherichia coli (2,5-dimethyltetrahydrofuran, dimethyl disulfide, 2-heptanone, 2,5-dimethylpyrazine, benzaldehyde, dimethyl trisulfide, 2-nonanone, nonanal, decanal, 2-undecanone, indole, and 2-tridecanone) were prepared from internal standards in water. The headspace gases were then analyzed using microAnalyzer™, a miniaturized Gas Chromatography-Differential Mobility Spectrometry (GC-DMS) system. Differential mobility spectra showed monomer peaks of the analytes with the observed retention times below 3 min. Dispersion voltages, determining the dependence of signal intensities and compensation voltages of each analyte on the applied radio frequency (RF) voltages, were recorded for positive and negative modes. It was found that at increasing RF voltages the monomer peaks of compounds of lower molecular masses tend to shift to more negative compensation voltages; whereas, those of higher molecular masses tend to shift to more positive compensation voltages. The shift results in increase separation among each peak. The signal intensities for all peaks, however, tend to decrease at higher RF voltages. The RF voltage which gave optimum peaks separation and signal resolution was 1,200 V (corresponds to 24 kV/cm). This study demonstrates the potential of microAnalyzer™ as an integrated gas chromatograph detector for a preliminary screening system in the on-site detection of E. coli in water. The operational principle of the instrument is also presented in this study.
Lena Ganda Saptalena, Klaus Kerpen, Andriy Kuklya, Ursula Telgheder
Plant parasitic nematodes are the most destructive group of plant pathogens worldwide and their control is extremely challenging. Plant Essential oils (EOs) and their constituents have a great potential in nematode control since they can be developed for use as nematicides themselves or can ... more
For over a century, ulcer has been a major cause of morbidity and mortality. Its treatment has progressed from vagotomy to proton pump inhibitors. However, the drugs used produce many adverse effects and are less effective than they ought to be. Therefore, there is a growing interest in alt ... more
Endophytic fungi are ubiquitous organisms found in the plants, residing intercellular or intracellular, at least for a portion of their lives without causing apparent symptoms of infection. Almost all plants are known to harbor endophytes. The choice of the plant to be used for exploring en ... more
Physicists describe how they have synthesized a new material that belongs to the iron-selenide class of superconductors, called LixFe2Se2(NH3)y, in a paper about to be published in EPJ B. The work was carried out by Ernst-Wilhelm Scheidt from the University of Augsburg and colleagues. This ... more
The U.S. federal government is significantly underestimating the costs of carbon pollution because it is using a faulty analytical model, according to a new study published in the Journal of Environmental Studies and Sciences. A more appropriate accounting of costs would pave the way to cle ... more
Springer advisory board member Vladimir V. Dmitriev, along with fellow scientists Yuriy M. Bunkov and Igor A. Fomin, have been named winners of the 2008 Fritz London Memorial Prize for their discovery and understanding of the "Phase Coherent Spin Precession and Spin Superfluidity of 3He-B." ... more