Mass spectrometry method for accurate mass determination of unknown ions

摘要

The invention relates to accurate determination of the position coordinate that is the location, frequency or time coordinate of an ion peak in a mass spectrum, as the basis for an accurate mass determination of the ions.;The invention consists of fitting a suitable function, e.g. a superposition of bell-shaped curves, to all peaks of a peak group simultaneously instead of using one isolated mass peak only, and applying a suitable abundance distribution for all the peaks of the measured group, e.g. of an isotopic pattern. The true mass distances between the individual peaks of the peak group and the ratio of their widths are usually known. The distances between the peaks of an isotopic pattern can, for instance, be derived in a good approximation from mean compositions of the substances of a chemical class. During curve fitting by a mathematical optimization process, in the simplest case only the position coordinate and the width of the bell-shaped curves are varied. If the pattern used is an isotopic pattern, a precise position determination of the monoisotopic ions of the isotope group is obtained automatically, even if the monoisotopic peak is not visible at all. For organic substances, in the simplest case only the pattern of the carbon isotopes in that chemical class are used for pattern fitting.