Determination of CO2 in gaseous samples using a monosegmented flow system and conductimetric detection Original Research Article

The monosegmented approach to flow analysis was employed for determination of low contents (100–1000 ppmv) of CO2 in gaseous samples. The front bubble of the flow pattern constitutes the gaseous sample. The sample is pumped through a glass tube (2 mm i.d., 80 cm long) by deionised water. The film of water present in the tube wall absorbs the CO2 present in the sample. The liquid monosegment collects, by convection movement of the fluid, the layer containing the partially ionized CO2, while the second bubble restricts the dispersion of the collected specimens. The conductivity of the liquid monosegment is monitored at the end of the glass tubing and is proportional to the CO2 content in the gaseous sample. The system has been optimized for determination of CO2 in the 50–1000 ppmv range. For the experiment, 100 μl of sample is employed and the system can perform 60 determination per hour. The relative standard deviation for the signals of standards in the 100–900 ppmv range was ca. 3%. Comparison with a gas chromatographic method revealed a mean relative difference of 7% for samples containing CO2 in the 20–700 ppmv range. The system employing conductimetric detection does not employ any reagent, is very simple and suitable for field monitoring of CO2 present in the atmosphere, indoors and outdoors.