Precision mass measurement

The absence of a sharp line at approximately 14 ppm indicated that ring opening to a n-butyl substituent did not occur. Precise mass measurements further showed that each concentrate has the same molecular weight (186) which confirmed that ring opening did not occur as implied by the work of Curran et al. [7] in which experimention was done with Tetralin. 

The Py-MS technique has been used extensively to characterize synthetic polymers, biopolymers, and fossil fuels (5-8,10, 11). In this work the technique has been modified by using a mass spectrometer which provides precise mass measurements directly upon pyrolysis. The advantage of this approach is two... 

The Py-MS experiments have provided detailed information on the labile organic structures found in the maceral concentrates. The utility of being able to obtain precise mass measurements is demonstrated in Table II where a small selection of peaks from the pyrolysis of the Brazil Block seam sporinite is listed. Note that at nominal m/z = 108 and 122 there are actually three distinct peaks corresponding to a quinone, an alkyl-phenol and a hydrocarbon. Normally with nominal mass pyrolysis data these peaks would only be assigned to alkyl phenols. All three peaks... 

This study has demonstrated that the Py-MS technique using precise mass measurements can be useful for characterizing macerals. Furthermore, the information derived from the... 

It has been shown that high resolution and precise mass measurements are important in the MS characterization of very complex mixtures (9-11.15). This is demonstrated in Table II where the six ion peaks found at nominal... 

Evidence for fluorenone (12) as a minor product of the pyrolysis (a small peak at mass 180 that persisted at reduced ionizing voltage) was indeed found. Direct-coupled gas chromatography-mass spectrometry clearly identified a minor component as fluorenone and a precise mass-measurement on a high-resolution mass spectrometer established C13H80+ as the empirical formula of the major component of nominal mass 180. 

Sulfur compound preferred to hydrocarbon because of precise mass measurement (0.000 error for C22H14S, 0.0034 for C25H10) and because no reasonable aromatic structure exists for a C25H10 hydrocarbon. 

Mass Spectrometry Bulletin (http //www.rsc.org/is/database/msbhome.htm) This is a current awareness bulletin providing information on mass spectrometry and related ion processes. The bulletin is sub-divided as follows instrument design and techniques isotopic analysis, precision mass measurement, isotope separation, age determination, etc. chemical analysis organic chemistry atomic and molecular processes surface phenomena and solid-state studies and thermodynamics and reaction kinetics. The database... 

D. C. Muddiman, A.P. NuU, J.C. Hannis, Precise mass measurement of a double-stranded 500 base-pair (309 kDa) polymerase chain reaction product by negative ion ESI-FT-ICR-MS, Rapid Commun. Mass Spectrom., 13 (1999) 1201. 

Another useful possibility is to use ESI in the negative ion mode, which yields a better signal for nucleotides. Multiply charged ions of the type (M — wH)"- are formed. Precise mass measurements for synthetic oligonucleotides with as many as 132 residues have been reported.27... 

RainviUe, S. Thompson, J.K. Pritchard, D.E. An ion balance for ultra-high-precision mass measurements. Science 2004, 303, 334—338. 

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