The mass spectrum of sulfur (S,) obtained with the ion trap mass spectrometer is compared with that obtained using an E-B spectrometer. Each ion in the spectrum is examined for fragmentation and the vapor shown to consist mostly of the SB oligomer. The chemical ionization spectra using methane, isobutane, ammonia, and water are also examined and an estimate made of the proton affinity of Ss. Us...

We present a procedure for the profiling of the volatile carboxylic acids and neutral compounds in blood or urine using the direct injection of the acidified sample into a gas chromatograph interfaced with a mass spectrometer by a jet separator. The non-volatile components remain at the head of the SP-1000 column while the volatile components move through the column. Up to sixty physiological s...

Materials and Methods: All the reagents were received from Sigma Aldrich Chemical Co. and used without further purification. Solvents were purchased from commercial sources and purified by reported protocol.1 Spectroscopy grade solvents were used for physical studies. 1H NMR and 13C NMR experiments were done on a Bruker DPX-400 MHz and 500 MHz NMR machine and all the data were calibrated agains...

Photodissociation with 157 nm light was implemented in an ABI model 4700 matrix-assisted laser desorption ionization (MALDI) tandem time-of-flight (TOF) mass spectrometer for peptide analysis. With a homemade computer program to control the light timing based on the m/z of each precursor ion, the photodissociation setup was seamlessly automated with the mass spectrometer. Peptide photodissociat...

Field studies among diverse biomes demonstrate that mass-based nitrogen concentration at leaf and canopy scales is strongly related to carbon uptake and cycling. Combined field and airborne imaging spectrometry studies demonstrate the capacity for accurate empirical estimation of forest canopy N concentration and other biochemical constituents at scales from forest stands to small landscapes. I...

A multichannel mass spectrometer based on the rectilinear ion trap (RIT) analyzer was designed and constructed for simultaneous high-throughput analysis of multiple samples. The instrument features four parallel ion source/mass analyzer/detector channels assembled in a single vacuum chamber and operated using a common set of control electronics, including a single rf amplifier and transformer c...

1. General Information All reactions were carried out in flame-dried glassware under an atmosphere of argon or nitrogen using anhydrous solvent. Dichloromethane was dried by passage through activated alumina columns. n-Propylamine was distilled from activated zinc dust and stored over sodium hydroxide. All other reagents were purchased from Acros, Aldrich, Alfa Aesar or Strem and used as receiv...

Mass spectrometry has been regarded as one of the most valuable analytical instruments since any compound has its intrinsic mass value. However, mass spectrometry can only be used to measure the mass-tocharge ratio (m/z) of a charged particle. Therefore, ionization process is usually needed unless the particle to be measured has an intrinsic charge. Nevertheless, the ionization efficiency is us...

Nanoflow electrospray ionization has been used to introduce intact Escherichia coli ribosomes into the ion source of a mass spectrometer. Mass spectra of remarkable quality result from a partial, but selective, dissociation of the particles within the mass spectrometer. Peaks in the spectra have been assigned to individual ribosomal proteins and to noncovalent complexes of up to five component ...