2272800 Acidity Reagent Set, 10-4000 mg/L CaCO₃

Acidity Reagent Set measures acidity in the range between 10 and 160 mg/L CaCO₃ and in the range from 100 to 4000 mg/L CaCO₃ in water, wastewater and seawater. The product uses Methyl Orange and Phenolphthalein (Total) Acidity method (8201, 8202). Article 2272800 may be used to analyze up to 100 tests.

Acidity Reagent Set includes:

• Bromphenol Blue Indicator Powder Pillows (p/n 1455099)
• Phenolphthalein Indicator Powder Pillows (p/n 94299)
• Sodium Hydroxide Titration Cartridge, 0.1600 N (p/n 1437701)
• Sodium Hydroxide Titration Cartridge, 1.600 N (p/n 1437901)

Before starting analysis:

• It is required to collect samples in clean glass or plastic bottles with tight-fitting caps.
• It is necessary to prevent the agitation of the sample and exposure to the air.
• It is required to increase the sample temperature to room temperature before analysis.
• It is recommended to use TitraStir Titration Stand to hold the Digital Titrator and stir the sample.

Procedure for CaCO₃ measurement

Select sample volume and attach the appropriate cartridge to the Digital Titrator from the table in the working procedure description. Turn the delivery knob to eject air and a few drops of titrant. After that reset the counter to zero. In order to measure methyl orange acidity, it is required to mix the sample and Bromphenol Blue Indicator Powder Pillow in the 250mL Erlenmeyer flask and add titrant until the color changes from yellow to blue-violet (pH 3.7). To analyze phenolphthalein (total) acidity, it is necessary to mix the sample and Phenolphthalein Indicator Powder Pillow in the 250mL Erlenmeyer flask and add titrant until the color changes from colorless to light pink color. Calculate concentration using the multiplier (see manual).

Summary of method

After adding bromphenol blue indicator and titrating the sample with sodium hydroxide solution, the color changes at the endpoint pH of 3.7 that measures strong mineral acidity in the sample. After adding phenolphthalein indicator, titration of the sample continues until the indicator changes color at the endpoint pH of 8.3. Titration with sodium hydroxide solution includes both strong and weak acid species and measures total acidity. Testing results are expressed in mg/L as calcium carbonate at specified pH.

Sample preparation

Store the sample at or below 6 °C (43 °F) for up to 24 hours to preserve the sample for later analysis.