Time-resolved atmospheric pressure

Most ion-molecule techniques study reactivity at pressures below 1000 Pa however, several techniques now exist for studying reactions above this pressure range. These include time-resolved, atmospheric-pressure, mass spectrometry optical spectroscopy in a pulsed discharge ion-mobility spectrometry [108] and the turbulent flow reactor [109]. 

C. The Time-Resolved Atmospheric Pressure Ionization Mass Spectrometer (TRAPI)... 

Note The acronyms used here are OSPED (optical spectroscopy in a pulsed electrical discharge), FAMS (flowing afterglow mass spectrometry), SIFT (selected ion flow tube), TRAPI (time-resolved atmospheric pressure ionization mass spectrometry), PHPMS (pulsed high-pressure ionization mass spectrometry), ICRMS (ion cyclotron resonance mass spectrometry), and ADO (averaged dipole orientation collision rate theory). 

W.B. Norris H.P. Broida, Time Resolved Emission Spectroscopy in Acetylene-Oxygen Explosions , TR-33 (1969), (AD 714 730) 31) K.W. Reed L. Rudlin, Optical Spectra Produced by 13-gm Pentolite Spheres in Several Gases at Atmospheric Pressure , NOLTR-69-37 (1969), (AD 689 354) 32) D.E. Chasan G. 

Figure 4 represent the XRD results for Tobermorite dehydration using the in-situ XRD set up. It clearly shows the time-resolved evolution of the Tobermorite structure during dehydration obtained with the above mentioned heating procedure under atmospheric pressure. Many authors [7,13] describe the first step of Tobermorite dehydration [14 A-11 A] as being a reversible process. 

McEwen et al. have utilized another ambient technique called atmospheric pressure solids analysis probe (ASAP) [84,85] and interfaced it with TWIM-MS [86], This source is now available commercially on the Synapt instrument. They have used m/z vi drift time plots to define compound classes in CTude oil analysis and to resolve isobaric compounds. Excellent agreement was demonstrated for drift times obtained from standards run individually and doped into the crude oil mixture. This work demonstrates the utility of mobility experiments to provide a degree of separation and classification in the study of very complex mixtures where chromatographic separation is either not possible or too time consuming. 

The rate constants for the reactions of OH with a series of organic nitroalkanes, nitrites and nitrates and of NO with a series of peroxy radicals were measured at 298 K and a total pressure of 1 atm. The rate constants were obtained using the absolute technique of pulse radiolysis combined with time-resolved UV-VIS spectroscopy. The results are discussed in terms of reactivity trends and the atmospheric chemistry. 

Oh, J.-S., Aranda-Gonzalvo, Y., Bradley, J.W. (2011) Time-resolved Mass Spectroscopic Studies of an Atmospheric-pressure Helium Microplasma Jet. J. Phys. D Appl. Phys. 44 365202. 

Complications of drug analysis were successfully resolved by the combination of TLC with MALDI-MS. TLC combined with MALDI-MS was used for analysis of psychotropic drugs (3,4-methylenedioxy methamphetamine, 4-hydroxy-3-methoxy methamphetamine, 3,4-methylenedioxy amphetamine, methamphetamine, p-hydroxy methamphetamine, amphetamine, ketamine, caffeine, chlorpromazine, triazolam, and morphine) in biological samples [42]. This technique was able to analyze 3,4-methylenedioxy methamphetamine (MDMA) and its metabolites in urine samples without sample dilution, and the detection limit of the MDMA spot was 0.05 ng/ spot. Crecelius and coworkers described the use of TLC with MALDI-MS/MS for the structural analysis of small drug molecules [43]. This method was successfully applied to analyze two representatives of nonsteroidal antiinflammatory drugs (tenoxi-cam and piroxicam), and pharmaceutically active compound UK-137,457 and one of its related substances UK-124,912. The feasibility of UTLC-atmospheric pressure (AP)-MALDI-MS was described for the analysis of small molecules (triazole, midazolam, verapamil, and metaprolol) [44]. The authors compared the selectivity and sensitivity between UTLC- and HPTLC-AP-MALDI-MS. It was observed that UTLC plates provided 10-100 times better sensitivity in MALDI analysis than the conventional... 

Time-resolved measurements of CH2O production have demonstrated that the lifetime of CH3SCH2O with respect to unimolecular decomposition is less than 30 js at 261 K and 10 Torr total pressure [45], However, in the atmosphere, reaction of the CH3SCH2O intermediate with O2 may be important. If, based on the 30 js lifetime upper limit (at 261 K and 10 Torr), the rate coefficient for reaction (5) is assumed to be ca. 35 000 s at atmospheric pressure and 298 K (probably a... 

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