Mass Spectrometer

The effect of chlorine on the analysis of three organic compounds (geosmin, 2-methylisoborneol (2-MIB) and methyl tert-butyl ether (MTBE)) in drinking water is elucidated. Three fibers for solid-phase microextraction (SPME) were employed for the extraction of the organic compounds from drinking water samples with and without free residual chlorine present. A gas chromatograph coupled with a mass spectrometer was used to analyze the compounds trapped by the fibers. The presence of chlorine substantially reduces the observed geosmin, 2-MIB, and MTBE concentrations. Depending on the analyte and chlorine concentrations, an experimental error of 10-70% may be observed due to the presence of free residual chlorine. The impact is larger for lower organic compound concentrations, and under higher residual chlorine conditions. To counteract the effect from residual chlorine, sodium thiosulfate was used to dechlorinate the water. After dechlorination the experimental error was less than 10%, ...

This program addresses the mechanism of NO reduction in pulverized coal flames using reburning. Using both thermodynamic and kinetic simulation combined with both pilot and bench scale experimental work, we propose to better define the conditions that lead to the destruction of NO, without the concomitant increase in other nitrogenous pollutants. Specifically, the interactions between NO and hydrocarbon constituents in the fuel, and the fate of fuel nitrogen are the focal points of this research. Three different experimental apparatus are being used to acquire data under different ranges of operation conditions. A shock tube and a bench scale flow reactor are used to investigate the interaction between NO and various gas, liquid and solid fuels. The shock tube operates at high temperatures (1000 to 2500/degree/K) and short reaction times (1 to 2.5 ms), while the flow reactor is designed for the investigation of long reaction times (about 1 sec) and relatively low temperatures (up to 1100/degree/C). 3 refs., 3 figs., 6 tabs.

This review paper describes a new technology, mass cytometry, that addresses applications typically run by flow cytometer analyzers, but extends the capability to highly multiparametric analysis. The detection technology is based on atomic mass spectrometry. It offers quantitation, specificity and dynamic range of mass spectrometry in a format that is familiar to flow cytometry practitioners. The mass cytometer does not

PM10 samples from a garden site (site A), an industrial-traffic intersection (site B), a residential site (site C) and an island site (site D) were collected at December 21-29, 2004; March 18-22, 2005; July 4-13, 2005 and October 24-28, 2005 in Xiamen. 15 priority PAHs compounds were analyzed by using a gas chromatograph/mass spectrometer (GC/MS). The abundance and origin of

Two complementary methods for identifying and measuring sulfonamide residues in eggs were developed for use in surveying eggs for potential drug residues. The first method uses liquid chromatography-tandem mass spectrometry (LC-MS-MS) to confirm the presence of sulfonamide residues in eggs. During its validation the limit of confirmation was estimated to be 5-10 ng/g (ppb) depending on the drug. Also, a method for measuring residue level by liquid chromatography with ultraviolet detection (LC-UV) was validated using the same extraction procedure as the confirmatory method. The determinative method was validated over the 50-200 ppb range. Samples were prepared by homogenizing whole egg, extracting with acetonitrile, and cleaning up with a C(18) solid-phase extraction cartridge. For confirmation, analytes were separated by gradient LC on a C(18) column, ionized by electrospray ionization (ESI), and detected by MS-MS with an ion trap mass spectrometer. For determination, analytes were separated by a different gradient LC procedure and detected by UV at 287 nm. Fifteen drugs were dosed individually in laying hens, and residues of parent drug and/or metabolites were found in eggs for all the drugs. Validation was based on repetitive analyses of control samples, control samples fortified at 100 ppb sulfonamides, and samples of blended incurred eggs.

Ceramide III was prepared by the cultivation of Saccharomyces cerevisiae. Ceramide III was partitioned from the cell extracts by solvent extraction and analyzed by normal phased high performance liquid chromatography (NP‐HPLC) using evaporative light scattering detector (ELSD) and mass spectrometer. The mobile phase was composed of chloroform and methanol. One linear gradient mode was applied to gain proper analysis of cell extracts. Quantitative analysis of ceramide was performed. Based on the analytical condition, the effect of cultivation temperature for the production of ceramide was investigated and the optimum cultivation temperature was found to be 30°C at pH 7. From the results of mass spectrometer analysis, C26 ceramide was the dominant cell culture. The fragment ions from the mass spectrum of ceramides III, which were of various molecular weights, from m/z = 237–677, were observed.

The success of a manned lunar outpost may require that indigenous resources be utilized in order to reduce the requirements for the periodic resupply from Earth for the human inhabitants. Some indigenous lunar resources do exist. For instance, studies of the lunar regoliths, acquired by the Apollo and Luna missions from several maria, indicate that upon heating in a vacuum, these soils evolve the volatile gases: helium (He), hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), nitrogen (N2), and sulfur dioxide (SO2). The He, H, C, and N were originally implanted by solar wind These gases would be valuable to supply life-support systems. For instance, the H2 could be used as a rocket fuel, or alternatively, reacted with the mineral ilmenite (FeTiO3), indigenous to the lunar soil, to yield water (H2O). In an enclosed structure irradiated by solar energy, the H2O, N2, and CO2 could be utilized to grow edible plants for lunar inhabitants. Alternatively, the H2O could be electrolyz...

ABSTRACT A new analytical method is presented for the compound-specific carbon and nitrogen isotope ratio analysis of a thermo-labile nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS). Two main approaches were used to minimise thermal decomposition of the compound during gas chromatographic separation: programmed temperature vaporisation (PTV) as an injection technique and a high-temperature ramp rate during the GC run. δ15N and δ13C values of RDX measured by GC-IRMS and elemental analyser (EA)-IRMS were in good agreement within a standard deviation of 0.3‰ and 0.4‰ for nitrogen and carbon, respectively. Application of the method for the isotope analysis of RDX during alkaline hydrolysis at 50°C revealed isotope fractionation factors ε carbon = −7.8‰ and ε nitrogen = −5.3‰.

Energy and Technology Review, January 1989, Lawrence Livermore National Laboratory, contains: An Expert System for Triple Quadrupole Mass Spectrometry, a powerful software tool for tuning an instrument; An Expert System to Control a Fusion Energy Experiment, a rule-based expert system that automates the critical process of conditioning new or rebuilt neutral beam sources; An Expert System for Tuning Particle-Beam Accelerators, a proof-of-concept prototype of an expert system for tuning particle-beam accelerators; Qualitative Reasoning and Symbolic Analysis for Engineering Design, a workstation package that uses qualitative reasoning and symbolic analysis to give the engineer insight into the behavior of his design at an early stage; Using Expert Systems in Treaty Verification, rule-based expert systems to aid in the verification of such treaties by automating the task of data interpretation for various seismic monitoring systems; and Monitoring and Interpreting Security Alarms, an expert system to assess security incidents. (TC)