Spectrometry programmed-scan

Temporal Devices. A temporal dispersive device uses a single channel which is scanned as a function or time to yield information on the intensities present in various resolution elements. Two basic approaches are possible (1) the detector may be scanned across a fixed spectrum or (2) the spectrum may be scanned across a fixed detector. In addition, these systems may be further differentiated on the basis of the manner in which the spectrum is scanned. Thus, linear-scan systems scan the spectrum at a constant, fixed rate. In contrast, programmed-scan systems have the capability of momentarily stopping at wavelengths of analytical interest, while spectral regions of little interest are rapidly scanned. For a complete review of the area of rapid-scanning spectrometry up to 1968, the interested reader should consult Volume T of Applied Optics which was entirely devoted to this subject. 

Gas Chromatography-Mass Spectrometry. A Finnigan 4500/Incos instrument with a 30-m X 0.32-mm i.d. capillary column coated with SP-B-5 was used. The GC parameters were as follows injector, 270 °C column oven temperature programmed, 50 °C (0.1 min, hold) 15 °C/min to 100 °C, 5 °C/min to 270 °C internal standard, anthracene-djo helium flow, 3.0 mL/min sample size, 3.0 /xL. MS conditions were as follows El, 70 eV scan (m/z), 35-650 daltons source temperature, 250 °C filament current, 0.5 A sensitivity, 10-8 A/V. (NOTE When the name of a compound is followed by (confirmed) , it means that the standard material was analyzed for confirmation under conditions identical to those of the sample when the name is followed by (tentative) , it means that the mass fragmentography showed the best fit (>80 ) based on the National Bureau of Standards [NBS] library computer search.)... 

Data-dependent software programs allow real-time decisions to be made during an analysis. This approach features a preestablished threshold for the detection of a peak during full-scan mass spectrometry and MS/MS scan modes. If a peak of interest is detected in real-time, then the mass spectrometer is switched from full-scan mode to another scan mode to obtain more information from the same analysis. For example, the system may be automatically switched to the production mode during the analysis of a chromatographic peak to obtain substructural information. Thus, more detailed information is obtained in fewer analyses. This powerful... 

The development and use of various protein sequence databases for automated search routines (Eng et al., 1994 Clauser et al., 1999) are an essential component of protein analysis that uses mass spectrometry techniques. These programs (i.e., SEQUEST, MASCOT) require only a few peptides for matching therefore, the absence of a match for a particular peptide does not affect the search performance. Using protein database searches provides an efficient way of confirming a putative sequence from corresponding full-scan mass spectrometry and MS/MS data. 

ISS ion-scattering spectroscopy LEIS low-energy ion scattering SEM scanning electron microscopy SIMS Secondary ion mass spectrometry TEM transmission electron microscopy TP temperature-programmed XANES X-ray absorption near edge spectroscopy. 

Gas Chromatooraphy-Mass Spectrometry. A Finnigan MAT 4500 GC/MS/INCOS system (Finnigan MAT, San Jose, CA) was used for analysis. A 60 m X 0.32 mm i.d. DB-WAX coiumn was empioyed for the headspace samples. The oven temperature wa programmed from 50 C to 180°C at 2 C/min. A 60 m X 0.32 mm i.d. DB-1 column was used for the sample prepared by vacuum SDE. The oven temperature was programmed from 30 °C (4 min isothermal) to 210 C at 2 C/mln. HeHum was used as the carrier gas at a flow rate of 3.2 mL/min. The column outlet was Inserted directly into the ion source block. The instnjment was operated in the electron impact mode at an ionization voltage of 70 eV. The mass spectrometer was repetitively scanned from 33 to 350 m/z in a one-second cycle. 

The carbon fiber support and the catalysts before and after reduction were characterized with various techniques, viz. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), temperature programmed reduction (TPR), Nz-physisorption, inductively coupled plasma emission spectrometry (Vista AZ CCD simultaneous ICP-AES) and hydrogen chemisorption. 

Gas chromatography/mass spectrometry (GC/ MS) of aromatic hydrocarbon fractions was done on an HP 6890 gas chromatograph equipped with an HP 7683 autosampler, a 60 m DB-1 column connected to an HP 5973 mass selective detector operated in the scan mode from 50 to 450 amu. On-column sample injection was done at programmed temperature at 3 °C above column oven temperature with constant flow helium carrier gas. The column oven programme initial temperature was 70 °C programmed to 315 °C (total run time 131.33 min). Internal standard (ortAo-terphenyl) at 300 ppm was used for quantification with data acquisition and integration on HP ChemStation software. Ratios may be found in Table 4. 

Fialin, M., Hdnoc, J., Remond, G. (1993) A survey of electron microprobe microanalysis using soft radiations difficulties and presentation of a new computer program for wavelength dispersive spectrometry. Scanning Microsc. Suppl, 7,153-166. 

---