A High Precision Procedure for Carbon Dioxide Determinations with the Carbon Dioxide Sensing Probe

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Abstract
A new general procedure for carbon dioxide determinations in gaseous and liquid samples has been developed. This procedure is based on the use of a commercial carbon dioxide sensing probe, incorporated into a thermostated glass cell protecting the probe from the environment and conveying gaseous grab subsamples (0.5-1 cm3, by means of a humidified carrier gas stream, against the membrane of the probe in a very reproducible manner. A peak-shaped curve (e.m.f. developed by the probe vs. time) is obtained. The peak height is the analytical information. Response and recovery times, sampling and calibration procedures, precision and accuracy have been investigated using synthetic gaseous and liquid samples. In case of liquid samples, gaseous subsamples are obtained from the head space above the sample. Outstanding features of the method are: the use of the carbon dioxide probe extended to gaseous samples; the improved performance in case of liquid samples; the long lasting validity of calibration curves.