Optical resolution of D, L amino acids by gas chromatography and mass spectrometry.
Optical scanning and resolution of D, L amino acids by gas-liquid chromatography and mass spectrometry
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Optical scanning and resolution of D, L amino acids by gas-liquid chromatography and mass spectrometry
Tandem column gas-liquid chromatography labeling technique for mass spectrometry, noting ketones exchange and data on deutrium and oxygen compounds
Continuous source for atomic fluorescence flame spectrometry using 150-watt xenon arc, total consumption atomizer-burner and low resolution monochromator
Ion mass spectrometry of D layer, using magnetic fields and cyclotron resonance principle
Book on mass spectrometry principles and application to ion and neutral atom composition of upper atmosphere
High resolution gas chromatography combined with mass spectrometry applied to analysis of pyrolysis products of isoprene from 300 to 1000 degrees C
Complex organic compounds analysis by fast- electrical-scanning high resolution mass spectrometry and gas chromatography
An amphoteric (cocamidopropylbetaine, CAPB) and a nonionic (alcohol polyethoxylate, AE) surfactant were characterized by electrospray ionization quadrupole ion trap mass spectrometry (ESI-MS) as to their homologue distribution and ionization/fragmentation chemistry. Quantitative methods involving reversed-phase gradient HPLC and (+)ESI-MSn were developed to directly determine these surfactants in hydroponic plant growth medium that received simulated graywater. The predominant homologues, 12 C alkyl CAPB and 9 EO AE, were monitored to represent the total amount of the respective surfactants. The methods demonstrated dynamic linear ranges of 0.5-250 ng (r2 > 0.996) for CAPB and 8-560 ng (r2 > 0.998) for AE homologue mixture, corresponding to minimum quantification limits of 25 ppb CAPB and 0.4 ppm AE with 20-microL injections. This translated into an even lower limit for individual components due to the polydispersive nature of the surfactants. The procedure was successfully employed for the assessment of CAPB and AE biodegradation in a hydroponic plant growth system used as a graywater bioreactor.
Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) holds promise to be a low-mass, compact in situ analytical capability for future landed missions to planetary surfaces. The ability to analyze a solid sample for both mineralogical and preserved organic content with laser ionization could be compelling as part of a scientific mission pay-load that must be prepared for unanticipated discoveries. Targeted missions for this instrument capability include Mars, Europa, Enceladus, and small icy bodies, such as asteroids and comets.
An overview of the physical principals of imaging spectrometry for detailed characterization of remote objects and of gas vapors is given. The terms Multi-spectral, Hyperspectral, and Ultra-spectral are defined within the framework of applications and instrument system design approaches.
Carbonaceous meteorites are derived from asteroids, although specific parent bodies are generally unknown. However, on September 24, 2023, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission delivered regolith from the carbonaceous B-type asteroid (101955) Bennu, enabling coordinated laboratory analysis of pristine samples, with a well characterized geological context, from an asteroid of known provenance. One of primary mission goals [1] was the identification and characterization of primordial organic matter present in the returned samples. We report results from the coordinated analyses of Bennu samples using UV fluorescence, two-step laser mass spectrometry (μ-L2MS) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).
Environmental barrier coatings (EBCs) are required for the use of silicon carbide (SiC)-based ceramic matrix composites (CMCs) in gas turbine engines, as they protect the SiO 2 thermally grown oxide (TGO) formed at the CMC/coating interface from volatilization in a combustion environment. Current-generation EBCs consist of a silicon bond coat and a rare earth (RE) silicate topcoat. The RE silicate topcoat is exposed to high-velocity steam during engine operation, and SiO 2 within the coating can preferentially volatilize to form Si(OH) 4 gas species, albeit at a lesser degree than SiO 2 alone. Therefore, it is of interest to investigate the stability of these materials in steam as a function of their RE. In this study, SiO 2 activity, which can be related to the partial pressure of Si(OH) 4 , was measured across the Gd 2 O 3 -SiO 2 phase diagram, which includes Gd 2 SiO 5 , Gd 9.33 (SiO 4 ) 6 O 2 , and Gd 2 Si 2 O 7 as line compounds, via Knudsen Effusion Mass Spectrometry (KEMS). Values obtained for the Gd 2 O 3 -SiO 2 system were compared to those of other RE2O3-SiO2 systems and contextualized in terms of EBC viability.
Apparatus for narrow pass band photoelectric spectrometry of stars of first spectral type
Atom concentration calculated for linear segments of analytical curves in atomic flame spectrometry
Lithium drifted germanium and silicon semiconducting detectors compared with thallium activated sodium iodide crystal scintillation counter for gamma spectrometry
Paper chromatography and mass spectrometry for analyses of pyrimidine and purine bases
Computer-coupled high resolution mass spectrometry impact on molecular structure studies
Chemical ionization mass spectrometry of pristane