Fast Exact Computation of the k Most Abundant Isotope Peaks with Layer-Ordered Heaps

Computation of the isotopic distribution of compounds is crucial to applications of mass spectrometry, particularly as machine precision continues to improve. In the past decade, several tools have been created for doing so. In this paper we present a novel algorithm for calculating either the most abundant k isotopologue peaks of a compound or the minimal set of isotopologue peaks which have a combined total abundance of at least p. The algorithm uses Serang's optimal method of selection on Cartesian products. The method is significantly faster than the state-of-the-art on large compounds (e.g., Titin protein) and on compounds whose elements have many isotopes (e.g., palladium alloys).