The current invention concerns a method for identifying the elemental composition of and/or quantifying the presence of mono-isotopic elements in a molecule in a sample by computing a solution of a system of linear equations ΣαEiαnα=Fi, whereby the set of numbers Fi comprises said set of relative peak heights from the aggregated isotopic distribution and the coefficients Eiα of said linear system comprise powers and/or power sums of roots rα,iα. The present invention also provides a method for analyzing at least part of an isotopic distribution of a sample, comprising obtaining data comprising at least one probability qj with which a j'th aggregated isotopic variant of said molecule with mass number Aj occurs within said aggregated isotopic distribution; and computing a probability qi with which an i'th aggregated isotopic variant occurs within said aggregated isotopic distribution, by taking a linear combination of said at least one probability qj.