THE DETERMINATION OF TOTAL DISSOLVED INORGANIC CARBON IN AQUEOUS-SOLUTIONS

Experimental results and theoretical considerations were utilized to d evelop a method for the precise and accurate determination of total di ssolved inorganic carbon (TDIC) in aqueous solutions. A method of prep aring standard solutions of Cs2CO3 from distilled deionized H2O which was initially stripped of ambient inorganic carbon (IC) with N2(g) at 6.90 x 10(4) Pa for 20 min allowed a means of calibration without syst ematic error. For a 0.20-mL sample, a quadratic working range of analy sis extended from the limit of detection, 1.05 x 10(-5) M IC, to 3.44 x 10(-3) M IC. Results are accurate to three significant figures. The smallest R2 observed over 4 yr was 0.997. For 0.05-, 0.10-, and 0.20-m L sample volumes, no significant effect of solution volume on detector response was observed. In order to expedite routine analysis, a means of preparing and storing secondary standard solutions of NaHCO3 for u p to 28 d was developed.