I would like to measure the dissolved carbon dioxide content of a sample of water. I was thinking that conductivity might change with carbon dioxide level, and also pH. I would like to have the measurement sample electronically, so current, voltage, conductivity / impedance (resistance, capacitance, inductance) would all be fine. My chemistry goes up to A-level; I am an engineer.
This paper looks helpful: http://www.sciencedirect.com/science/article/pii/S0144860910000683
Quoting from the abstract:
Many methods are available for the measurement of dissolved carbon dioxide in an aqueous environment. Standard titration is the typical field method for measuring dissolved CO2 in aquaculture systems. However, titrimetric determination of dissolved CO2 in marine water aquaculture systems is unsuitable because of the high dissolved solids, silicates, and other dissolved minerals that interfere with the determination. Other methods used to measure dissolved carbon dioxide in an aquaculture water included use of a wetted CO2 probe analyzer, standard nomographic methods, and calculation by direct measurements of the water's pH, temperature, and alkalinity. The determination of dissolved CO2 in saltwater based on partial pressure measurements and non-dispersive infra-red (NDIR) techniques with a CO2 gas analyzer are widely employed for oceanic surveys of surface ocean CO2 flux and are similar to the techniques employed with the head space unit (HSU) in this study. (...)