Equipment scanning mass spectrometer

A gas chromatograph equipped with a methylsilicone WCOT column is interfaced to a fast scanning mass spectrometer which is suitable for capillary column GC/MS analyses. The sample is injected either through a capillary splitter port or a cool on column injector capable of introducing a small sample size without overloading the column. The capillary column is interfaced directly to the mass spectrometer or by way of an open split interface or other appropriate device. 

A second use of arrays arises in the detection of traces of material introduced into a mass spectrometer. For such very small quantities, it may well be that the tiny amount of substance will have disappeared by the time a scan has been has been completed by a mass spectrometer equipped... 

The mass spectrum of TTX can directly be measured by fast atom bombardment- or secondary ion-mass spectrometry. In the former a JEOL JMS DX-300 mass spectrometer equipped with a JEOL JMA-3100 data system is used xenon provides the primary beam of atoms. Acceleration voltage of the primary ion is 3 kV. Scanning is repeated within a mass range of m/z 100 to 1000. 

A 20% polyethylene glycol succinate on Kieselguhr column (1.2 m, 443 K, 50 ml min helium carrier gas) was used for GC analyses. Deuterium-labelled compounds were analysed by NMR spectroscopy (JEOL C 60-HL equipment) after separation with a Carlo Erba Mod P preparative GC. Mass spectrometric analyses of the reaction mixtures were carried out with a Hewlett Packard 5890A GC instrument (25 m HP-20M column, 353-473 K) coupled with a 5970 MSD quadrupole mass spectrometer (El source, 70 eV, 1-s scans, HP 59970 MS ChemStation data system). 

Infrared spectra of individual fractions were determined by means of a Beckman IR-5 spectrophotometer equipped with a 5 X KBr lens-type beam condenser. Infrared spectra of selected reference compounds were obtained from samples which had been purified by chromatography. On the basis of identity of infrared spectra and retention data with those of authentic reference compounds, most of the peaks shown in Figures 1 and 2 were identified (15,16). To obtain information about minor components not detectable in the infrared spectra, mass spectra were obtained as components of an irradiated odor concentrate were eluted from a 10-foot, J/g-inch 5% Carbowax 20M column programmed from 20° to 160°C. at 1° per minute. These spectra were obtained on a modified model 14 Bendix Time-of-Flight mass spectrometer. Electron energy was set at 70 e.v., and spectra were scanned from m/e 14-200 in 6 seconds. 

In conclusion, the sensitivity and specificity for screening for oxidative metabolites by the three LC-MS methods are variable, compound-dependent, and complementary to each other. The MDF method requires a simple, generic full-scan analysis using a mass spectrometer equipped with high-resolution capability, and the accurate mass information obtained can provide empirical formula information for metabolites and their fragments. Since MDF employs a different detection... 

Figure 6.16 Stop-flow NMR spectra of the hydrolysis products of Remazol Black 5 acquired an LC-NMR-MS run 95% of the eluent was transfered to the NMR spectrometer and 5% t° the mass spectrometer. Equipment NMR spectrometer, Bruker DRX 600 probe head, 4 mm z-gradient LC probe between 256 and 1024 scans were acquired mass spectrometer, bruker Esquire-LC ion-trap machine, equipped with an ESI ionization source...

Early mass spectrometers were simply equipped with a SQ mass analyser merely suitable for full scan MS mode and selected ion monitoring. Even though SQ spectrometers are highly superior to UV-detectors with respect to selectivity, they still bear the risk of deterioration by matrix compounds of similar m/z values. Especially, peptides and small proteins may cause a series of diverse m/z values due to their multiple charge states after ES ionization potentially interfering with the analytes or IS [103, 105],... 

Synthetic peptide mixtures (1-2 mg) were dissolved in a mixture of 1% aq HC02H/MeCN (1 1). Positive-ion ESI mass spectra were recorded using a triple-quadnipole mass spectrometer API III equipped with a nebulizer-assisted electrospray ( ion spray ) source (Sciex, Thornhill, Ontario, Canada). The spectra were obtained as the sum of 5-10 scans at a step size of 0.2 p and a dwell time of 5 ms. 

Fast atom bombardment mass spectrometry. Fast atom bom-bardment/mass spectrometry (FAB/MS) analyses were performed on a VG ZAB-HF mass spectrometer equipped with an Ion Tech fast atom gun. Xenon gas was activated to 8 kv and 1.5 mA ion current for the fast atom generation. An accelerating voltage of 8 kV was applied to the FAB source. The mass spectrometer was scanned from 800 to 80 amu using an exponential down scan mode at 5 seconds per decade with a 1 second interscan time. The data were recorded with a PDP 11/24 computer and were processed with VG 11/250 software. 

The equipment used for this work consisted of a Hewlett-Packard 5710A GC, with on-coluitm injection, directly coupled to a VG7070E medium resolution double-focusing mass spectrometer. The GC coluitm employed was a 60 m fused silica capillary colurrm coated with a cross-linked methyl silicone stationary phase, DB-1. The initial temperature of the colurrm was 30°C, and after 4 minutes, the temperature was linearly programmed at 8°C/min to 270°C, and held at this final temperature for 15 minutes. The mass spectrometer was operated in the electron impact (El) mode, and the mass range of 20-700u was scanned once a second. The mass spectrometer was linked to an Incos data system which stored the acqnired mass spectra, and allowed these to be compared to the EPA/NIH Mass Spectral Data Base to assist with the identification of compounds detected. 

SAM Characterization. TDS and XPS were performed in a UHV chamber with a base pressure of 10 10 mbar. The apparatus is equipped with a x-ray photoelectron spectrometer (Leybold Heraues, EA 10/100), a quadrupole mass spectrometer (Balzers QMA 400) with a mass range from 1 to 500, and an Ar+-sputter gun. For TDS the sample was mounted on a steel plate, which can be heated by tantalum wires spot welded on the backside of the plate [12], AFM was performed ex situ using a Nanosurf Easy scan 2 scanning probe microscope in tapping mode. 

---