2447200 Calcium Hardness Reagent Set, LR, 10-160 mg/L mg/L CaCO₃

Article 2447200 measures calcium hardness in the range from 10 to 160 mg/L CaCO₃ in water, wastewater and seawater. The product uses EDTA Titration method (8204). Calcium Hardness Reagent Set can be used to conduct 40-100 tests.

Calcium Hardness Reagent Set includes:

• CalVer 2 Calcium Indicator Powder Pillows (p/n 85299)
• Potassium Hydroxide Standard Solution (p/n 28232H)
• EDTA Titration Cartridge, 0.0800 M (p/n 1436401)

Before you start take into account the following:

• Collect the sample in clean glass or plastic containers cleaned with detergent and rinsed with 1:1 nitric acid and deionized water.
• Use CalVer 2 Calcium Indicator Power Pillows (p/n 94799) or CalVer 2 Calcium Indicator Powder as alternative to CalVer 2 Calcium Indicator Power Pillow.

Procedure for CaCO₃ analysis (low range)

Firstly, select the sample volume, choose the titration cartridge and prepare the Digital Titrator. Secondly, swirl the collected sample, the content of the Potassium Hydroxide Standard Solution and the content of the CalVer 2 Calcium Indicator Powder Pillow in the 250mL Erlenmeyer flask. Thirdly, add titrant until the color changes from red to pure blue and calculate the concentration:

Digits used × digit multiplier = mg/L Ca as CaCO₃.

Summary of method

Potassium hydroxide is added to the sample to adjust the pH to 12 to 13 that causes magnesium hydroxide precipitate to form. Added CalVer 2 Calcium Indicator enters into reaction with calcium to giving red color. The added EDTA titrant enters into reaction with all the free calcium. After the EDTA has reacted with all of the free calcium ions, the EDTA removes the calcium from the indicator. The indicator color changes from red to blue. 

Sample preparation

Adjust the sample pH to 2 or less with concentrated nitric acid to preserve the sample for later analysis. Store the preserved sample at room temperature for up to 6 months.