PASCO EZ-2338 Total Hardness ezSample Field Titrator - Manual (Page 2)

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Test Method Description
The total hardness ezSample test method employs ethylenediaminetetraacetic acid (EDTA) titrimetric
chemistry.
1,2
In an alkaline solution, EDTA forms a chelated soluble complex with calcium and
magnesium ions. Calmagite is used as the endpoint indicator. Results are expressed as calcium
carbonate (CaCO
3 ). 1,2,3
NOTE: Because the ampoules have nonlinear scales, the accuracy of the ezSample field titrator kit varies with the
analyte concentration. At the low end of the test range, the accuracy is
± 5%. At the high end of the range, the
accuracy falls to
± 20%.
References
1. Method 2340C. APHA Standard Methods, 20th ed., p. 2-37, (1998).
2. Method 130.2. EPA Methods for Chemical Analysis of Water &Wastes. (1983).