Analysis of linear approaches to quantitative stable isotope methodology in mass spectrometry

Abstract

A general equation is derived which is applicable to all problems of ion overlap between a stable isotope internal standard and a sample to be measured. The approach is then extended to solve the problem of ion overlap between three components. The equations are general in terms of all possible isotopic contributions. Utilization of the principle of fixed ion ratios within an ion cluster allows the algebraic solution of the problem such that the final equations are linear in form. It appears that linear regression can be used to calculate the coefficients of the linear equations without loss of accuracy or precision and with a significant reduction in the time and computation needs necessary for the analysis. This approach is compared and contrasted to those developed by other workers.