Determination of Total Alkalinity and Calcium Concentration of Seawater Rapidly and Automaticly with Small-Amount Samples

The means of determing total alkalinity(A_t) and calcium concentration of small-amount seawater samples using one set of equipments is described. Using automatic potentiometric titrator (Metrohm* 798MPT Titrino), through termostating, increasing the titration reagent volume accuracy, accurate positioning equivalence point and regulating reagent volume every step added, At and calcium can be measured separately with high precision and limited time. The relative standard deviation of At is lower than 0.10% (plusmn2 mumol kg^-1) with a single sample consumption of 25cm3 and 9 min while the relative standard deviation of calcium is better than 0.25% (plusmn26 mumol kg^-1) , sometimes lower than 0.10% (plusmn10 mumol kg^-1) ,with a single sample consumption of 1.0 cm³ and 5 min.