Anal.Chim.Acta, 1977, 91, 181-188

Rapid determination of the "titration alkalinity" of
sea water by equilibration with CO2

Robin S. Keir1, Sam P. Kounaves and Alberto Zirino
Chemistry and Environmental Sciences Group, Naval Ocean Systems Center, San Diego, CA 92152 U.S.A.

Received 8 December 1976. Available online 14 November 2001.

Sea-water samples of salinities 31.88, 35.84, and 39.87‰ were acidified and then titrated with HCO3- under 1 atm. pressure of CO2. The resulting pH vs. HCO3- titration plots were interpreted in terms of an ion pairing model, and an equation relating pH and alkalinity was derived. This expression was used to develop a rapid, volume-independent technique to measure alkalinity. The method has an accuracy of ±1% and a precision of ±0.35% (one sigma), and lends itself to the analysis of flowing samples and to samples of small volume.

1 Current Address: Department of Geology, Yale University, New Haven, CT, U.S.A.