Computation of the isotopic distribution in two dimensions.

A new algorithm for the calculation of the isotopic distribution is described here. The extreme levels of detail, the coarser structures (approximately 1 Da) and the sharper irregular details (approximately millidaltons), get split in separate dimensions. Consequently, dense sampling can be concentrated in the close informative surrounding of the isotopic peaks. The one-dimensional isotopic distribution is reconstructed by allotting the abundances along the mass axis. Performance is evaluated with small and relatively large compounds (300 Da to 90 kDa) of diverse composition including challenging polyisotopic elements. The superiority over well-established methods in terms of accuracy, speed, and memory resources is clearly demonstrated for high and ultrahigh resolution ranges by a program implementing the algorithm.