2447600 Total Hardness Reagent Set, Buret, LR, 0-2500 mg/L CaCO₃

Total Hardness Reagent Set measures total hardness in the range of 0-2500 mg/L as CaCO₃ in water, wastewater and seawater. The product uses EDTA Titration method (8226). Article 2447600 can be used to conduct up to 100 tests.

Total Hardness Reagent Set includes:

• ManVer 2 Hardness Indicator Powder Pillows (p/n 85199)
• Hardness 1 Buffer Solution (p/n 42432)
• TitraVer Hardness Titrant, 0.020 N (p/n 20553)

Before you start take into account the following:

• Collect the sample in clean glass or plastic container cleaned with detergent and rinsed with 1:1 nitric acid and deionized water. 
• Use TitraStir Titration Stand to hold the buret and stir the sample.
• Adjust the pH to 7 using sodium hydroxide solution before sample analysis.

Procedure for CaCO₃ measurement

In order to determine total hardness, choose the sample volume and titrant. Add titrant in the 25mL buret. Swirl the collected sample and 1mL of Hardness 1 Buffer Solution in the 250mL Erlenmeyer flask. Pour the content of ManVer 2 Hardness Indicator Powder Pillow and swirl to mix. Continue adding titrant from the buret in the Erlenmeyer flask until the color changes from red to pure blue and calculate the concentration:

mL of titrant × multiplier = mg/L total hardness as CaCO₃

Summary of method

Buffer solution is added to the sample to adjust the pH to 10.1. Organic dye, calmagite, is the indicator for the test that enters into reaction with calcium and magnesium ions giving red-colored complex. The EDTA titrant enters into reaction 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.