Comparison of infrared and mass-spectrometric measurements of carbon-13/carbon-12 ratios

Abstract

The δ¹³C values of 20 breath samples and 10 tank-CO₂ samples (δ¹³C values ranged from −31.3 to +148.9% vs PDB) and the CO₂ concentrations of three breath samples and 10 tank-CO₂ samples were measured with a commercial prototype of a diode-laser i.r. spectrophotometer, MAT I. The results were compared with those obtained by gas-isotope-ratio mass spectrometry and by gas chromatography. Precisions (s_x, n = 10) of 0.2% and 0.6% were calculated for ¹³C/¹²C ratios and CO₂ concentrations, respectively, using the MAT I system.