Continuous measurements of stable carbon isotopes in CO2 with a near-IR laser absorption spectrometer.

Highlights: [•] We measured stable carbon isotope ratios of CO2 by a laser absorption spectrometer. [•] The H2O broadening coefficients of CO2 were determined. [•] The effect of humidity on δ13C determination was examined. [•] The spectrometer keeps constant measurement conditions over 12-h periods. [ABSTRACT FROM AUTHOR]