2448000 Total Hardness Reagent Set, LR, 10-160 mg/L CaCO₃

Article 2448000 measures total hardness in the range from 10 to 160 mg/L CaCO₃ in water, wastewater and seawater. Total Hardness Reagent Set uses EDTA Titration method (8213). One set is enough for 40-100 tests.

Total Hardness Reagent Set includes:

• ManVer 2 Hardness Indicator Powder Pillows (p/n 85199)
• Hardness 1 Buffer Solution (p/n 42432)
• EDTA Digital Titrator Cartridge, 0.0800 M (p/n 1436401)

Before you start take into account the following:

• Use 4 drops of Hardness 2 Indicator Solution or 0.1-g scoop of ManVer 2 Hardness Indicator Powder as alternative to ManVer 2 Hardness Indicator Powder Pillow.
• Adjust the pH to 7 with sodium hydroxide solution before analysis of the collected sample.
• Dilute the sample to approximately 100mL with deionized water if the sample volume is less than 100mL.
• Correct testing results for the dilution caused by the volume additions.

Procedure for total hardness as CaCO₃ analysis

Select the appropriate sample volume, choose the titration cartridge and attach to the Digital Titrator from the table in the working procedure description. Then transfer the collected sample into 250mL Erlenmeyer flask. Pipet 2mL of Hardness 1 Buffer Solution and swirl to mix. After that add ManVer 2 Hardness Indicator Powder Pillow and swirl the content of the 250mL Erlenmeyer flask. Continue adding titrant until the color changes from red to pure blue and calculate the concentration (see manual for detailed information regarding calculation of the testing results):

Digits used × digit multiplier = mg/L total hardness as CaCO₃

Summary of method

Buffer solution adjusts the pH to 10.1. An organic dye, calmagite, is the indicator for the test that enters into reaction with calcium and magnesium ions and gives a red-colored complex. The EDTA titrant reacts with all of the free calcium and magnesium ions in the sample. After the EDTA has reacted with all of the free magnesium ions, the EDTA removes the magnesium ions from the indicator. The indicator color then changes from red to blue.