The Picarro G2121-i Isotopic CO2 Analyzer is capable of measuring stable isotope ratios of carbon in CO2 and total CO2 concentration when coupled to a sample preparation front-end such as an Elemental Analyzer (EA), a Dissolved Inorganic Carbon acidification module or with Picarro’s Combustion Module (CM) designed by Costech. The analyzer is based on Picarro’s unique Cavity Ring Down Spectroscopy (CRDS), a time-based measurement utilizing a near-infrared laser to measure a spectral signature of the molecule. Gas is circulated in an optical measurement cavity with an effective path length of up to 20 kilometers. A patented, high-precision wavelength monitor makes certain that only the spectral feature of interest is being monitored, greatly reducing the analyzer’s sensitivity to interfering gas species, and enabling the high-precision 13C isotope measurements even if there are other gases present. As a result, the analyzer maintains high linearity, high precision, and high accuracy over a two fold dynamic range (2000ppm-4000ppm) with minimal calibration required. Precise temperature and pressure control systems designed into the Picarro G2121-i ensure accurate measurements over long periods of time with minimal use of calibration gases or standard reference material. The analyzer itself is exceptionally rugged and insensitive to changing ambient temperature, essentially drift and maintenance free, and requires no consumables, thereby offering significant ease-of-use and cost of ownership benefits.