DIC-δ13C Analyzer

Model AS-D1

Apollo SciTech’s DIC-δ13C analyzer (model AS-D1) is designed for simultaneous and precise analyses of Dissolved Inorganic Carbon (DIC) and δ13C for natural water samples and is based on the Picarro’s G-2131i Analyzer. The analyzer consists of a highly efficient gas bubbling reactor, a mass-flow-controller to control the carrier gas flow precisely, a digital pump for transferring accurate amounts of reagent and sample. The analyzer uses an electronic cooling system to control the reactor temperature and, with the help of a Nafion tube, to eliminate the water vapor.

The analyzer has a broad analytical range as the sample and standard volume can be changed by users (currently tested for 1-4 ml). This feature is useful for analysis of seawater and coastal waters. As coastal samples often have large concentration differences and thus require a variable volume and a 100% extraction of CO2 from the sample within a reason period. The analyzer has a relatively fast processing rate and high precision. The current model is designed for discrete bottle sample analysis in a lab or continuous underway analysis on board a ship. A multiport valve is used for the multi-sample version.

Below: demo unit of the Apollo Scitech’s DIC-δ13C Analyzer (model: AS-D1) together with a Picarro’s G-2131i Analyzer.

Additional Information

A typical integration curve/peak with time is given below. The peak is almost symmetrical. DIC is the area integration under the curve. δ13C is the average of signal when CO2 concentration is above 100 ppmv.

pCO2 vs. integration time and δ13C vs. time.


  • Precision (DIC): ±0.1% for seawater (or ±2 µmol/kg)
  • Precision (DIC-δ13C): ±0.1%
  • Sample volume: 1-4 ml per analysis
  • Time: <12 min per analysis
  • Software: Apollo SciTech software included
  • Power Supply: Universal (100-240 V)
  • Carrier Gas: Compressed air (with a CO2 scrubber)
Note: a Picarro’s G-2131i Carbon Isotope Analyzer should be provided by the user.