An analyzing portion searches a mass spectrum for a mass peak exceeding a threshold level and adds the mass corresponding to the searched peak to the mass differences listed in an adduct ion table stored in a table, thereby forming a quasi-mass spectrum. The analyzing portion compares the formed quasi-mass spectrum with a measured mass spectrum in terms of mass. If agreement in mass between both the spectra is found, an index S is incremented by one and finally a total value of the index S is calculated. The analyzing portion then searches for another mass peak exceeding the threshold level and executes a similar process. Resulting values of the indexes S are compared with each other and probabilities of m/z and adduct ions are output to a display portion. Emergence frequency is counted for each of detected ion types and stored in storage means. If the measurement is executed in a predetermined number of times, then a greater weight is allocated to the ion types having larger emergence frequency, followed by updating the adduct ion table stored in the table. That arrangement realizes a method and apparatus for measuring and analyzing a mass spectrum by which a quasi-molecular ion and hence the molecular weight of a sample can be quickly estimated with high accuracy while preventing an error from being mixed in the process of analysis.
A method and apparatus are provided for identifying unknown chemical structures that are related to one or more known structures. Measured masses of the unknown structures (US members) are compared with the expected masses of the known structures (DS members). The mass differences between US members and DS members are compared with changes in mass (.DELTA.M) between molecules analyzed as a function dependent upon structure (.DELTA.S). The mass difference is considered as a differential function, .DELTA.M/.DELTA.S, the result of which is calculated for each ion in the US when compared with each ion in the DS. These values are then correlated with values that would be expected based on assumed possible structural modifications. In addition, higher order differential functions, such as .DELTA..sup.2 M/.DELTA.S.sup.2, can be used as needed to allow for correlation of structures in which more than one structural motif has changed.
The invention relates to a method and device enabling time-saving, comparative mass spectrometric analysis of serial samples corresponding to a reference, for example serial samples of a product, by conditioning by means of a reference sample and forming a pattern of a reduced number of fragment ions, said fragment ions having selected from individual mass spectrums of the same separated by gas chromatography, and forming a pattern of a reference random sample from overall mass spectrograms of several reference samples reduced accordingly.
A mass spectrometer and a method of mass spectrometry are disclosed wherein periodic background noise is effectively filtered out from the mass spectral data. An overall mass window is superimposed upon the mass spectral data. The overall mass window preferably comprises 21 nominal mass windows each preferably having a width of 1.0005 amu. Each nominal mass window preferably comprises 20 channels. An intensity distribution relating to all the first channels of the 21 nominal mass windows is determined. An intensity quantile is determined from the intensity distribution. The intensity quantile is taken to represent the background intensity in the first channel of the central nominal mass window. This process is repeated for the other channels so that the background intensity across the whole of the central nominal mass window is estimated and then subtracted from the raw mass spectral data comprising the central nominal mass window. The overall mass window is then preferably advanced approximately 1 amu and the process is repeated multiple times.
An unknown polymer is pyrolyzed by a pyrolizer and a produced mixture of pyrolytic products is separated into the pyrolytic products by a separating column. The separated pyrolytic products are detected by a mass spectrometer to generate a chromatogram. Ion intensities contained in all total ion intensities making up peaks in the chromatogram are added, for each ion of the same mass, to plot a combined mass spectrum of the unknown polymer. Combined mass spectra of a plurality of known polymers are generated in the same manner as with the combined mass spectrum of the unknown polymer, and stored as a library. The library is searched for the combined mass spectrum of one of the known polymers which agrees with a high probability percentage with the combined mass spectrum of the unknown polymer.
An apparatus for ion attachment mass spectrometry provided with an ion emitter for emitting positively charged metal ions, an ionization chamber for causing attachment of the metal ions to a gas to be detected, a third component gas introduction mechanism for introducing a third component gas into the ionization chamber, and a mass spectrometer for mass separation and detection of the detected gas with the metal ions attached. The third component gas introduction mechanism is provided with three types of third component gases and selectively introduces one type of third component gas from the three types of third component gases. Due to this, the occurrence of interference peaks due to macromers of third component gases with each other, macromers of third component gases and high concentration ingredients, etc. is prevented and accurate mass analysis made possible.
