The application of a simple algorithm to isotope ratio measurements by gas chromatography/combustion/isotope ratio mass spectrometry

A simple algorithm has been derived for the calculation of isotopic composition from gas chromatography/combustion/mass spectrometry. It has the advantage of automatically removing background contributions to the peaks, hence avoiding user subjectivity in placing the baseline. The algorithm has been tested under near ideal conditions of a perfectly resolved peak and also in the more realistic case where there is chromatographic overlap in the peak wings. Performance is shown to be superior to that obtained from the software supplied with the equipment. A spreadsheet implementation of the algorithm has been made available for download via the Internet.