Molecular weight determination mass spectrometry

Various techniques have been used depending on the polymer and the nature of the chemical transformations infrared, ultraviolet and electron spin resonance spectroscopy, vapour phase chromatography, mass spectrometry, molecular weight and gel fraction determination, luminescence measurements, etc. These techniques have recently been discussed in a well-documented review on analytical methods applied to the study of the photodegradation of polymers [19]. 

Analysis of polymer additives by mass spectrometry has, for the most part, been limited to molecular weight determination of the solvent-extracted components [4,254], Field desorption is a good ionisation... 

Johnson, Y. A. Nagpal, M. Krahmer, M. T. Fox, K. F. Fox, A. Precise molecular weight determination of PCR products of the rRNA intergenic spacer region using electrospray quadrupole mass spectrometry for differentiation of B. subtilis and... 

Electrospray Ionization Mass Spectrometry - Fundamentals, Instrumentation and Applications 1st ed. Dole, R.B., editor John Wiley Sons Chichester, 1997. Fenn, J.B. Electrospray Wings for Molecular Elephants (Nobel Lecture). Angew. Chem., Int. Ed. 2003, 42, 3871-3894. Fuerstenau, S.D. Benner, W.H. Molecular Weight Determination of Megadalton DNA Electrospray Ions Using Charge Detection Time-of-Flight-MS. Rapid Commun. Mass Spectrom. 1995, 9, 1528-1538. 

The presence of the P4 molecule was indicated by osmometric molecular weight determinations, mass spectrometry, and by the easy displacement, even at -78°C, of the intact P4 unit by carbon monoxide or phosphane ligands. The infra-red and Raman spectra showed bands attributable to a bound P4 molecule under 3 or Cg... 

There are a number of mass spectrometry techniques available and directly applicable to polymers. Since high polymers have high molecular weights, determination of unbroken chains is not usual. Even so, determination of structures of ion fragments of segments of the polymers is straightforward and a valuable tool in determining the unit structure. 

Fast atom bombardment mass spectrometry (FABMS) has become an important addition to the ionization techniques available to the analytical chemist in recent years. It has been particularly useful in a number of diverse applications which include molecular weight determinations at high mass, peptide and oligosaccharide sequencing, structural analysis of organic compounds, determination of salts and metal complexes, and the analysis of ionic species in aqueous solutions. This paper will focus on some aspects of the quantitative measurement of ionic species in solution. The reader is referred to a more comprehensive review for more details of some of the examples given here as well as other applications (1). 

The advent of FAB mass spectrometry has allowed the routine molecular weight determination of polar molecules, without derivatization, up to ca 3,000 Daltons, and in exceptional cases, within 1 mass unit to the region of 8,000 Daltons. This advance, coupled with FAB fragmentation, and enzymic digestion techniques, has allowed the rapid solution of a number of problems in protein and peptide chemistry - problems which were hitherto rather difficult to solve. Examples are given. 

Mass Spectrometry Usage of analytical devices that can determine the mass (or molecular weight) of proteins and nucleic acids, the sequence of protein molecules, the chemical organization of almost all substances and the identification of gram-negative and gram-positive microorganisms. 

The elucidation and confirmation of structure should include physical and chemical information derived from applicable analyses, such as (a) elemental analysis (b) functional group analysis using spectroscopic methods (i.e., mass spectrometry, nuclear magnetic resonance) (c) molecular weight determinations (d) degradation studies (e) complex formation determinations (f) chromatographic studies methods using HPLC, GC, TLC, GLC (h) infrared spectroscopy (j) ultraviolet spectroscopy (k) stereochemistry and (1) others, such as optical rotatory dispersion (ORD) or X-ray diffraction. 

Fuerstenau SD, Benner WH (1995) Molecular weight determination of megadalton DNA electrospray ions using charge-detection time-of-flight mass spectrometry. Rapid Com-mun Mass Spectrom 9 1528-1538... 

We have recently determined the structural parameters and composition of some asphaltene samples obtained from the Synthoil and Exxon Donor Solvent (EDS) liquefaction processes. The particular EDS sample used was sufficiently volatile for analysis by ultrahigh resolution mass spectrometry, so we could obtain very detailed data on its composition in terms of the distribution of individual carbon-number homologs. Information from this approach, integrated with data from NMR, IR, molecular weight determinations, elemental analyses, and separations furnished us with a novel and detailed insight into the nature of these asphaltenes. The excellent agreement observed between composites calculated from the detailed MS data, where available, and the averages determined by NMR, IR, and elemental analyses reinforces the credibility of the approaches used and allows extrapolations to heavier samples that are not amenable to detailed MS characterization. 

Figure 13.3. Two-dimensional map showing the LC-MS analysis of an extract of red clover under investigation for the management of menopause. Reversed phase separation was carried out using a Ci8 HPLC column in the time dimension and negative ion electrospray mass spectrometry was used for compound detection and molecular weight determination in the second dimension.

K. Straub and K. Chan, Molecular weight determination of proteins from multiply charged ions using thermospray ionization mass spectrometry. Rapid Commun. Mass Spectrom., 4 (1990) 267. 

If it turns out to be a new alkane, the proof of structure can be a difficult job. Combustion and molecular weight determination give its molecular formula. Clues about the arrangement of atoms are given by its infrared and nmr spectra. (For compounds like alkanes, it may be necessary to lean heavily on x-ray diffraction and mass spectrometry.)... 

Capillary isoelectric focusing coupled to mass spectrometry has gained popularity in recent years (by analogy to two-dimensional gel electrophoresis). Additional information obtained from mass spectrometry includes not only precise molecular-weight determination but also the possiblity for peptide sequencing. Analysis of hemoglobin variants, recombinant proteins, and monoclonal antibodies have been demonstrated [1,7,8]. 

Structure CCCLXXI was tentatively proposed for the alkaloid A on the ground of the molecular weight determination (mol. wt. 402 mass spectrometry) and a degradation study which is not clearly described. 

In the solid state, compound 37 is a prism-type entity in which two almost planar Sn4Cl402 layers are linked together by four trimethylene spacers. This solid state stmcture is retained in solution, as is evidenced by (i) two equally intense " Sn and four pairs of equally intense NMR signals, (ii) electrospray mass spectrometry, and (iii) molecular weight determination. 

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