Determination of the triple oxygen and carbon isotopic composition of CO from atomic ion fragments formed in the ion source of the 253 Ultra high-resolution isotope ratio mass spectrometer.

Rationale: Determination of δ O values directly from CO with traditional gas source isotope ratio mass spectrometry is not possible due to isobaric interference of C O O on C O O. The methods developed so far use either chemical conversion or isotope equilibration to determine the δ O value of CO . In addition, δ C measurements require correction for the interference from C O O on C O O since it is not possible to resolve the two isotopologues.