MOT (Molecular orbital theory for fragmentation) hitherto proposed is extended to be able to predict semiquantitatively all fragments and molecular ions by introducing a slow unimolecular type of fragmentation in addition to the fast type hitherto assumed. Ratio of the slow and fast fragmentation is determinable automatically on the basis of the electron densities allotted to the HOMO at the lone pair electrons and skeletal bonds, respectively. The calculated intensities of main peaks in the mass spectra showed a good coincidence with the experimental ones, and their changes with ionizing voltage could be also explained to some extent.

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The coupling of a quadrupole mass spectrometer with a spark source has been studied for elemental analysis, the technique being termed spark source quadrupole mass spectrometry (SSQM). According to the physical and instrumental considerations we estimated the available sensitivity and basic ion optics of the novel instrument. After instrumental design was completed the spark source quadrupole mass spectrometer was constructed and performance was studied.

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Secondary ion mass spectrometry has been used for the analysis of a series of commercial optical glasses of borosilicate system. Quantitative reductions of secondary ions from the glasses having different degrees of surface charge build-up were made by a calculation method involving sensitivity factors derived from glasses selected arbitrarily as reference materials from the series. The matrix effect was negligible in the glasses used and the sensitivity factor calculation gave results within a factor of 1.2 of theoretical expectations when mass peaks obtained were strong enough to quantify.

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The amino acid sequence of a peptide is determined by the combination of the Edman degradation and the field desorption mass spectrometry. The kind of the PTH amino acid is determined by measuring the molecular weights of the residual intact peptides before and after the degradation. The molecular weights are determined from the (M+H)⁺ peaks of FD mass spectra. The sequence determinations of the peptide fragments in a peptide mixture can be done parallelly and simultaneously by this method.

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It has been found that field desorption mass spectrometry was one of the most useful methods to analyze the distribution of molecular weight, polymerization initiator and reaction mechanism in polyalkylene oxides.
The mass spectra of polypropylene glycols showed two series of quasi-molecular ion peak patterns, repeating every 58 mass units corresponding to the monomer unit C₃H₆O, I+58n+1 and I+58n+23 (I: molecular weight of polymerization initiator). The latter series of peak patterns correspond to the mass number of each cluster ions with sodium molecule. In the same way, the mass spectrum of polyethylene glycol showed two series of repetitive quasimolecular ion peak patterns, I+44n+1 and I+44n +23. In addition to analyzing main composition units and initiators, the distribution of molecular weight in these polymers could be estimated from the intensities of each peak height. High molecular compounds whose molecular weight, near 1,000, could not be detected by conventional CI-MS and by GC with silyl derivatives, were identified very easily by this method.
The mass spectrum of block copolymer showed characteristic ion peak patterns composed of numerous ion peak groups. The distribution of molecular weight of polyethylene oxide and polypropylene oxide parts in the block copolymer and the information of reaction mechanism could be deduced from the accumulated intensities of all ions containing the same additive mole number of ethylene oxide or propylene oxide monomer.

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