Electro-Chemical Devices (ECD) CA6 Hardness Analyzer - Manual (Page 36)

Fill a 1 liter volumetric flask to 2/3rds capacity with DI water. Add 200 ml of ethanolamine while stirring
the solution. Fill the volumetric flask to the gauge line (1 liter). Transfer to the reagent 2 container
provided with the analyzer.
5.1 Method of Analysis
The Hardness determination is a colorimetric analysis using a 572 nm LED and a heated colorimetric cell
of 16 mm diameter. After rinsing the hydraulic lines, the sample is pumped with the peristaltic pump
into the colorimetric cell. The reference measurement of the initial color is taken. Reagent 1, the
Cresolphthalein solution, is added using Micro Pump 1 and Reagent 2, the ethanolamine solution, is
added with Micro Pump 2. The solutions are mixed and a violet color develops proportionally to the
calcium and magnesium ions present. Absorbance is measured at the end of the reaction and the result
is displayed as Hardness as CaCO
3
ppb/ppm.
Wavelenght: 572 nm led
Before proceeding with the analyzer Start-Up, check that all installation (Section 4.0) and
reagent preparation (Section 11.0) operations have been properly completed. Please
verify that all suggestions and recommendations have been followed.
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