Abstract
Continuous analysis of the carbonate system in water surrounding calcifying organisms is an important technique in the study of calcification. Simultaneous measurement of pH and alkalinity is the most convenient way to describe the carbonate system in a water sample. These data are suitable for incubation experiments using small calcifying organisms because the water volume needed for analysis is small. In this report we describe a modified method focused on reduced volume (ca. 1 mL) samples based on the one-point titration method. The precision of this method, incorporating a correction using the masses of the water sample and added acid, is 0.1 - 0.2% (relative standard deviation). On the other hand, with no correction, the precision was 0.1 - 1.0% (relative standard deviation). Even though values showed a systematic error, precision was maintained through correction based on concurrent measurement of commercially available standards. This method allows us to describe the carbonate system in a small amount of water with sufficient precision and accuracy to investigate the mechanism of calcification using only a pH meter.
