The HI4001-40 fill solution is a chloride ion-containing electrolyte that is required to provide a reference potential for the HI4101 ammonia gas sensing ion selective electrode (ISE). As ammonia diffuses through the gas permeable membrane, the thin film of electrolyte on the surface of the pH sensing glass undergoes a pH change. The change in pH of the filling solution is proportional to the concentration of ammonia gas in the solution. The HI4001-40 is four bottles of 30 mL ammonia filling solution that ensure optimum measurement performance from the HI4101 ammonia ISE.
