Mass spectrometry effects

Shute, L. A. Gutteridge, C. S. Norris, J. R. Berkeley, R. C. W. Reproducibility of pyrolysis mass spectrometry effect of growth medium and instrument stability on the differentiation of selected Bacillus species. /. Appl. Bacteriol. 1988,64,79-88. 

M. G. Electron Multipliers in Mass Spectrometry Effect of Molecular Structure. Rev. Sci. lustrum. 1956, 27, 109. 

Rivera, S. Vilaro, F. Canela, R. 2011. Determination of carotenoids by liquid chromatography/mass spectrometry Effect of several dopants. Anal. Bioanal. Chem. 400 1339-1346. 

Berberich, D.W. Yost, R.A. Negative chemical-ionization in quadrupole ion-trap mass-spectrometry-effects of applied voltages and reaction-times. J. Am. Soc. Mass Spectrom. 1994, 5, 757-764. 

England TG, Jenner A, Aruoma OI, Halliwell B. Determination of oxidative DNA base damage by gas chromatography-mass spectrometry. Effect of derivatization conditions on artifactual formation of certain base oxidation products. Free Radic Res 1998 29 321-330. 

A comparative study of in- and post-source decays of peptide and preformed ions in matrix-assisted laser desorption ionization time-of-flight mass spectrometry effective temperature and matrix effect./. Am. Soc. Mass Spectrom.,... 

Meija, J. and Mester, Z. (2007) Signal correlation in isotope ratio measurements with mass spectrometry effects on uncertainty propagation. Spectrochim. Acta B, 62, 1278-1284. Meija, J. and Mester, Z. (2008) Uncertainty propagation of atomic... 

GJ van Berkel, F Zhou. Chemical electron-transfer reactions in electrospray mass spectrometry effective oxidation potentials of electron-transfer reagents in methylene chloride. Anal Chem 66 3408-3415, 1994. 

MP Heyes, SP Markey. Quantification of quinolinic acid in rat brain, whole blood, and plasma by gas chromatography and negative chemical ionization mass spectrometry effects of systemic L-tryptophan administration on brain and blood quinolinic acid concentrations. Anal Biochem 174 349-359, 1988. 

Longerich, H. P. (1993). Oxychlorine ions in inductively coupled plasma mass spectrometry Effect of chlorine speciation as Cl- and C104. J. Anal. At. Spectrom. 8(3), 439-444. 

Nyomora, A. M. S., Sah, R. N., Brown, P. H., and Miller, R. O. (1997). Boron determination in biological materials by inductively coupled plasma atomic emission and mass spectrometry Effects of sample dissolution methods. Fresenius J.Anal. Chem. 357(8), 1185. 

Richter, R. C., Koirtyohann, S. R., and Jurisson, S. S. (1997). Determination of technetium-99 in aqueous solutions by inductively coupled plasma mass spectrometry Effects of chemical form and memory.]. Arml. At. Spectrom. 12(5), 557. 

Valles-Mota, J. P, Remandez de la Campa, M. R., Garcfa-Alonso, J. I., and Sanz-Medel, A. (1999) Determination of cadmium in biological and environmental materials by isotope dilution inductively coupled plasma mass spectrometry effect of flow sample introduction methods. J. Anal. At.. Spectwm., 14,113-20. 

In many applications in mass spectrometry (MS), the sample to be analyzed is present as a solution in a solvent, such as methanol or acetonitrile, or an aqueous one, as with body fluids. The solution may be an effluent from a liquid chromatography (LC) column. In any case, a solution flows into the front end of a mass spectrometer, but before it can provide a mass spectrum, the bulk of the solvent must be removed without losing the sample (solute). If the solvent is not removed, then its vaporization as it enters the ion source would produce a large increase in pressure and stop the spectrometer from working. At the same time that the solvent is removed, the dissolved sample must be retained so that its mass spectrum can be measured. There are several means of effecting this differentiation between carrier solvent and the solute of interest, and thermospray is just one of them. Plasmaspray is a variant of thermospray in which the basic method of solvent removal is the same, but the number of ions obtained is enhanced (see below). 

Samples to be examined by inductively coupled plasma and mass spectrometry (ICP/MS) are commonly in the form of a solution that is transported into the plasma flame. The thermal mass of the flame is small, and ingress of excessive quantities of extraneous matter, such as solvent, would cool the flame and might even extinguish it. Even cooling the flame reduces its ionization efficiency, with concomitant effects on the accuracy and detection limits of the ICP/MS method. Consequently, it is necessary to remove as much solvent as possible which can be done by evaporation off-line or done on-line by spraying the solution as an aerosol into the plasma flame. 

The incidence of these defects is best determined by high resolution F nmr (111,112) infrared (113) and laser mass spectrometry (114) are alternative methods. Typical commercial polymers show 3—6 mol % defect content. Polymerization methods have a particularly strong effect on the sequence of these defects. In contrast to suspension polymerized PVDF, emulsion polymerized PVDF forms a higher fraction of head-to-head defects that are not followed by tail-to-tail addition (115,116). Crystallinity and other properties of PVDF or copolymers of VDF are influenced by these defect stmctures (117). 

The combined techniques of gas chromatography/mass spectrometry (gc/ms) are highly effective in identifying the composition of various gc peaks. The individual peaks enter a mass spectrometer in which they are analyzed for parent ion and fragmentation patterns, and the individual components of certain resoles are completely resolved. 

The use of separation techniques, such as gel permeation and high pressure Hquid chromatography interfaced with sensitive, silicon-specific aas or ICP detectors, has been particularly advantageous for the analysis of siUcones in environmental extracts (469,483—486). Supercritical fluid chromatography coupled with various detection devices is effective for the separation of siUcone oligomers that have molecular weights less than 3000 Da. Time-of-flight secondary ion mass spectrometry (TOF-sims) is appHcable up to 10,000 Da (487). 

Infrared Spectrophotometry. The isotope effect on the vibrational spectmm of D2O makes infrared spectrophotometry the method of choice for deuterium analysis. It is as rapid as mass spectrometry, does not suffer from memory effects, and requites less expensive laboratory equipment. Measurement at either the O—H fundamental vibration at 2.94 p.m (O—H) or 3.82 p.m (O—D) can be used. This method is equally appticable to low concentrations of D2O in H2O, or the reverse (86,87). Absorption in the near infrared can also be used (88,89) and this procedure is particularly useful (see Infrared and raman spectroscopy Spectroscopy). The D/H ratio in the nonexchangeable positions in organic compounds can be determined by a combination of exchange and spectrophotometric methods (90). 

With today s technology, the definition of the surface as it effects a material s performance in many cases means the outer one or two monolayers. It is the specific chemistry of these immediate surface molecules that determines many of the chemical and physical properties. Therefore, it is important to have available a tool that is able to characterize the chemistry of these layers. One such method that has met with considerable success is Static Secondary Ion Mass Spectrometry (SIMS). 

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