The double spike toolbox

The double spike technique is a well established method for correcting for instrumental mass fractionation in mass spectrometry. The precision of the technique is controlled by the choices of double spike composition and the proportions in which the double spike and sample are mixed. To make these choices easier, we provide software (“the double spike toolbox”) for calculating optimal double spikes, which are chosen purely on the basis of minimising error propagation. In addition, we provide “cocktail lists” of optimal double spikes for all 33 elements that have 4 or more naturally occurring isotopes, using some sensible default parameters. As examples, we discuss the application of the software to Fe, Pb, and Ca isotopes.