Gerlach, GeraldGeraldGerlachLambrecht, ArminArminLambrechtOelßner, WolframWolframOelßner2022-03-052022-03-052019https://publica.fraunhofer.de/handle/publica/25718010.1002/9783527688302.ch3Methods of analytical chemistry are used to separate, identify, and quantify chemical components with respect to chemical structure and composition. This chapter explains the two most important techniques to measure CO2 analytically using physical methods: spectroscopy and gas chromatography. It describes the analytical determination of dissolved carbon dioxide in water with chemical methods. Spectroscopy is a term used to refer to the measurement of radiation intensity as a function of wavelength. Gas spectroscopy - as it is used also for the detection of CO2 concentrations in gases - exploits the behaviour of gas molecules to act as mechanical resonators. Laser absorption spectroscopy is the suitable method to exploit the narrow absorption lines of the ro‐vibrational transitions of molecular gases. Gas chromatography is a technique that is used in analytical chemistry for separating and analysing compounds that can be vaporized without decomposition.engas chromatographycarbon dioxidelaser absorption spectroscopymechanical resonators621book article