Mass-Spectrometer Method

An intercomparison of the mass spectrometer method with an LIF instrument, however, was not as good. While the slope of the plot of LIF versus the MS measurements was 0.73, the r value was only 0.26, in part due to poor laser performance in the LIF instrument during the studies (Mather et al., 1997). 

Table 9.1 Comparison of inorganic mass spectrometic methods for determination of trace elements in solid materials. 

Boyd, R.K., Tandem mass spectrometry quadropole and hybrid instruments, Metftodi nzymo/. 193, 154-200, 1990 Jonscher, K.R. and Yates, J.R., 111, The quadrupole ion trap mass spectrometry — a small solution to a big challenge. Anal. Biochem. 244, 1-15, 1997 Chemushevich, I.V., Loboda, A.V., and Thomson, B.A., An introduction to quadrupole-time-of-flight mass spectrometry, J. Mass Spectrom. 36, 849-865, 2001 Ens, W. and Standing, K.G., Hybrid quadrapole/time-of-flight mass spectrometers for analysis of biomolecules. Methods Enzymol. 402,49-78, 2005 Payne, A.H. and GUsh, G.L., Tandem mass spectrometry in quadrupole ion trap and ion cyclotron resonance mass spectrometers. Methods Enzymol. 402, 109-148, 2005. 

Kock, R. Delvoux, B. Tilhnanns, U. Greihng, H. A candidate reference method for the determination of uric acid in serum based on high-performance hquid chromatography, compared with an isotope dilution-gas chromatography-mass spectrometer method. J. Chn. Chem. Clin. Biochem. 1989, 27, 157-162. 

FIGURE 18.3 The Object Browser of the Excel Visual Basic for Applications Integrated Development Environment is set up to explore the Mass Spectrometer Method Server Library (MSMethodSvr.dll) provided with Sciex Analyst version 1.3. 

Durand, G., P. Gille, D. Fraisse, and D. Barcelo. 1992. Comparison of gas chromatographic-mass spectrometic methods for screening of chlorotriazione pesticides in soil. /. Chromatogr. 603 175-184. 

The mass spectrometer method of chemical analysis which employs isotope dilution techniques has wide application in nuclear chemistry and physics, particularly in low-level detection work. There are many problems which require a quantitative measure of the amount of a particular element or isotope present in a sample in amounts less than one part per million. Sensitive mass spectrometers and the availability of tracer isotopes make the solution of these problems possible. 

Alternatively, the protein can be partially digested by an enzyme like trypsin. The fragments of this tryptic digest can then be separated and their molecular weights can be measured with a mass spectrometer. Methods available for such analysis are matrix assisted laser desorption ionisation (MALDI) time of flight (TOE)... 

A mass spectrometic method for determining the sequence and molecular weight of protected oligonucleotides containing phosphodiester groups has been developed using califomium-252 plasma desorption techniques. It has been dem-... 

C26.05 Cl 344-97 Standard Test Method for Isotopic Analysis of Uranium Hexafluoride by Single-Standard Gas Source Mass Spectrometer Method... 

Two reactions similar to (6A) have been studied. Wadiida, Nfartinez, and Bayes measured the steady-state concentration of HCO in the presence of O2, using a photo-ionization mass spectrometer (Method Xm), and calculated kso = (3.4 0.7) X 10 dm mol s at 297 K. Reaction (SO) almost certainly IHroceeds via a direct bimolecular st involving virtually no activation enogy. 

Busch et al. (1971) purified Eu by a fractionating column arrangement. The baffles of the column were at different temperatures due to their distance from the high frequency induction coil which heated the crucible containing the crude metal. The temperature of the various baffles was not reported. Eu with total impurities less than 0.02 at.% was obtained as determined by mass spectroscopy. The reason for the higher purity of this Eu compared to the Eu purified by sublimation (see table 2.5) is not clear but could be due to differences in analytical techniques, since the purification methods are essentially the same. The mass spectrometer method used by Busch et al. (1971) to analyze the Eu was not checked against standard methods such as vacuum fusion for H, Kjeldahl for N, combustion for C and neutron activation for O. As explained in ch. 37C, the mass spectrometric results for these impurities could be in error by a factor of 10. 

An apparatus permitting accurate determination of trace impurities in Grade-A helium by mass spectrometer methods was designed andbuilt in this laboratory. The device concentrates the impurities by freezing them out in a coil-and-trap assembly cooled by liquid helium, at which temperature all the impurities are solids. A known volume of helium is passed at reduced pressure through the trap and the concentration ratio is determined. Samples of the concentrated impurities are analyzed directly by mass spectrometer. Concentration ratios from 25,000... 

Isotopic analysis by double-standard mass-spectrometer method 23-29... 

Fragmentation experiments such as precursor ion scans using triple-stage quadrupole and ion trap mass spectrometers methods provide insights can identify conmiOTi and characteristic product ions and allow the detection of minor ergot alkaloids not included in routine analyses today. Ion trap detection allows several fragmentations (MSn experiments) that can enhance the ability to elucidate the structures of unknown ergot alkaloid derivatives. 

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