Instrument: Automatic titrator
Instruments that incrementally add quantified aliquots of a reagent to a sample until the end-point of a chemical reaction is reached.
The open-cell potentiometric acid titration system was developed by the laboratory of A.G. Dickson. Briefly, a known amount of seawater is added to an open cell temperature controlled beaker. Hydrochloric acid is added using a Methrom Dosimat to a pH of 3.5-4.0 and allowed to stabilize to remove CO2 gas formed by the addition of acid. Small aliquots of hydrochloric acid are then added to pH of ~3.0. The titration is monitored by a glass electrode and the total alkalinity of the sample is calculated using a non-linear least-squares method following Dickson et al. (2007).