Dynamic solid phase microextraction for sampling of airborne sarin with gas chromatography-mass spectrometry for rapid field detection and quantification

A portable dynamic air sampler and solid phase microextraction were used to simultaneously detect, identify, and quantify airborne sarin with immediate analysis of samples using a field portable gas chromatography-mass spectrometry system. A mathematical model was used with knowledge of the mass of sarin trapped, linear air velocity past the exposed sampling fiber, and sample duration allowing calculation of concentration estimates. For organizations with suitable field portable instrumentation, these methods are potentially useful for rapid onsite detection and quantification of high concern analytes, either through direct environmental sampling or through sampling of air collected in bags.     

Promotion effects in the oxidation of CO over zeolite-supported Pt nanoparticles

Well-defined Pt-nanoparticles with an average diameter of 1 nm supported on a series of zeolite Y samples containing different monovalent (H+, Na+, K+, Rb+, and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations have been used as model systems to investigate the effect of promotor elements in the oxidation of CO in excess oxygen. Time-resolved infrared spectroscopy measurements allowed us to study the temperature-programmed desorption of CO from supported Pt nanoparticles to monitor the electronic changes in the local environment of adsorbed CO. It was found that the red shift of the linear Pt-coordinated CO vibration compared to that of gas-phase CO increases with an increasing cation radius-to-charge ratio. In addition, a systematic shift from linear (L) to bridge (B) bonded CO was observed for decreasing Lewis acidity, as expressed by the Kamlet-Taft parameter alpha. A decreasing alpha results in an increasing electron charge on the framework oxygen atoms and therefore an increasing electron charge on the supported Pt nanoparticles. This observation was confirmed with X-ray absorption spectroscopy, and the intensity of the experimental Pt atomic XAFS correlates with the Lewis acidity of the cation introduced. Furthermore, it was found that the CO coverage increases with increasing electron density on the Pt nanoparticles. This increasing electron density was found to result in an increased CO oxidation activity; i.e., the T(50%) for CO oxidation decreases with decreasing alpha. In other words, basic promotors facilitate the chemisorption of CO on the Pt particles. The most promoted CO oxidation catalyst is a Pt/K-Y sample, which has a T(50%) of 390 K and a L:B intensity ratio of 2.7. The obtained results provide guidelines to design improved CO oxidation catalysts.     

Kaliumcadmiumjodid zur Werthbestimmung mehrerer pharmaceutischer Pr?parate

Ohne Zusammenfassung     

Analysis of the ν3 and ν1 infrared bands of GeH4

The high-resolution infrared spectrum of GeH₄ in the region 2020 to 2200 cm^?1 was analyzed. Most of the observed lines were assigned to transitions of the ν₃ and ν₁ bands of the five naturally occurring isotopic species. The spectrum was fitted by diagonalizing the v₃ = 1 and v₁ = 1 Hamiltonians coupled by the dominant vibration-rotation interaction term. For each isotopic species, about 100 transitions were fitted with an overall standard deviation of 0.006 cm^?1, using only 10 adjustable parameters. The five sets of parameters obtained are consistent with the expected isotope effects.     

Exclusive processes in quantum chromodynamics: Evolution equations for hadronic wavefunctions and the form factors of mesons

The predictions of quantum chromodynamics for meson form factors at large momentum transfer are given. Evolution equations are derived which determine the structure of hadronic wavefunctions at short distances from their form at large distances. The eigenvalues of the evolution equations appear as exponents in anomalous logarithm corrections to the nominal power law of form factors determined by dimensional counting. The results lead to detailed tests of the spin and scaling structure of QCD at short distances. The predictions for the charged pion, kaon and rho form factors and the γ → π⁰ transition form factor of the photon are absolutely normalized at asymptotic momentum transfer.     

Analytical methods for AMC and EBG characterizations

AMC and EBG behaviors are respectively characterized by reflection phase method and dispersion diagram. A fast and simple analytical model based on transmission line theory is proposed for each analysis. The validity of these analytical methods is verified by a comparison between circuit representations, measurements and numerical results.     

Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H]⁺) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H]⁺ ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d₁₅ provided evidence that [M+H]⁺ production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H]⁺ ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.