Applications of mass spectral techniques and

Carbohydrates and other oxygen heterocycles, applications of mass spectral techniques and stereochemical considerations in, 42, 335 Carbolines, 3, 79... 

Oxygen heterocycles, applications of mass spectral techniques and stereochemical... 

The final chapter is concerned with the application of mass spectral techniques in heterocyclic chemistry, in particular to carbohydrates and other oxygen heterocycles, and is authored by J. R. Jocelyn Pare, K. Jankowski, and J. W. ApSimon. 

A number of indirect methods have been developed with mass spectrometric detection to rapidly study non-covalent complexes for drug screening purposes [2]. Among the most promising and simple indirect methods that overcome the limitations described above for directly studying non-covalent complexes by mass spectrometry is the application of size exclusion techniques in the spin column format for the screening and analysis of drug-protein complexes under optimum mass spectral sensitivity conditions [11-13]. 

The above experiments are generally difficult to perform and the interpretation of the results may not necessarily be straightforward. The low abundance of the neutral products collected and the likelihood of mass spectral interference between reagents and products make these techniques applicable only to special cases. An independent approach to this problem has been proposed by Marinelli and Morton (1978) who have used an electron-bombardment flow reactor allowing in principle for larger collection of neutral products followed by glc and mass spectral analysis. 

The present article deals with the applications of mass spectrometry to the structural analysis of carbohydrate derivatives. The mass-spectral technique has now become a useful supplement to chemical methods, and provides ready solution of a variety of problems which were a stumbling block in the classical approaches. 

Pyrolysis MS (PyMS) has been applied to the characterisation and identification of a variety of microbial systems over a number of years (for reviews see [25-27]) and, because of its high discriminatory ability [28-30], presents a powerful fingerprinting technique applicable to any organic material. Whilst the pyrolysis mass spectra of complex organic mixtures may be expressed in the simplest terms as sub-patterns of spectra describing the pure components of the mixtures and their relative concentrations [24], this may not always be true because during pyrolysis intermolecular reactions can take place in the pyrolysate [31-33]. This leads to a lack of superposition of the spectral components and to a possible dependence of the mass spectrum on sample size [31]. However, suitable numerical methods (or chemometrics) can still be employed to measure the concentrations of biochemical components from pyrolysis mass spectra of complex mixtures. 

NM R experiments (ID and 2D, homonuclear and heteronuclear) are the preeminent techniques for the determination of molecular structures. However, careful application and analysis of mass spectral data can provide sufficient information to postulate tentative structures. In this respect, the application of tandem MS experiments, sometimes in conjunction with selective derivatization of the unknown compound, can be very informative about the stmcture. The high-resolution mass spectral data are critical to the support of NMR-deduced stmctures by providing molecular formulae for unknowns. 

Mass spectral techniques in heterocyclic chemistry applications and stereochemical considerations in carbohydrates and other oxygen heterocycles, 42, 335 Mass spectrometry of heterocyclic compunds, 7, 301 of nucleic acids, 39, 79 Medium-large and large 7r-excessive heteroannulenes, 23, 55 Meso-ionic compounds, 19, 1 Metal catalysts, action on pyridines, 2, 179 Metalation, directed, of pyridines, quinolines, and diazines, 52, 187... 

Mass spectral technique, application to and stereochemical investigations of carbohydrates and other O-heterocycles 87AHC(42)335. 

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