2429600 Silica Reagent Set, 1-100 mg/L SiO₂

Silica Reagent Set measures silica in the range of 1-100 mg/L SiO₂ in water, seawater, boiler water and ultrapure water. The product uses Silicomolybdate method (8185). Each package contains 100 Powder Pillows. The product can be evaluated using all Hach spectrophotometers except DR820, DR2000, DR3000 and PC II. Article 2429600 may be used for 10 mL sample analysis.

Silica Reagent Set includes:

• Acid Reagent Powder Pillow for HR Silica (p/n 2107469)
• Citric Acid Powder Pillow (p/n 2106269)
• Molybdate Reagent Powder Pillow for HR Silica (p/n 2107369)

Before starting analysis:

• It is required to collect the sample using clean plastic bottles with tight-fitting caps.
• Increase the sample temperature to room temperature.
• The sample temperature must be between 15-25 °C (59-77 °F) to receive accurate testing results.

Procedure for SiO₂ evaluation

In order to determine silica 1-100 mg/L SiO₂, start program 656 Silica HR. Swirl 10 mL sample and Molybdate Reagent Powder Pillow in the cell. After that pour Acid Reagent Powder Pillow for HR Silica in the cell and stir the sample cell content. After 10 minutes, add the content of Citric Acid Powder Pillow to the cell. Swirl the sample cell and start the instrument timer for 2 minutes. After 2 minutes, prepare the blank cell and install in the cell holder. Remove the blank cell, insert sample cell in the instrument and analyze testing results.

Summary of method

Silica and phosphate enter into reaction with molybdate ion under acidic conditions forming yellow silicomolybdic acid complexes and phosphomolybdic acid complexes. Citric acid destroys the phosphate complexes. The color should be evaluated using spectrophotometer (at 452 nm measurement wavelength) or colorimeter (at 420 nm recommended wavelength).