The HI4005-45 solution is for the conditioning and storage for the HI4105 carbon dioxide gas sensing ion selective electrode (ISE). Measurement of carbon dioxide in solutions is determined by a pH change of the internal thin film of electrolyte. This conditioning and storage solution is necessary to keep the glass pH sensing element hydrated in order to accurately determine carbon dioxide concentrations. The HI4005-45 is a 500 mL bottle of conditioning and storage solution that ensures optimum measurement performance from the HI4105 carbon dioxide ISE.