Analytical Method: Sulfate in building materials

Instrument and Reagents:

Cat.No. 173016 Spectroquant^® VIS Spectrophotometer Prove 100 or
Cat.No. 173017 Spectroquant^® UV/VIS Spectrophotometer Prove 300 or
Cat.No. 173018 Spectroquant^® UV/VIS Spectrophotometer Prove 600 or
Cat.No. 109748 Spectroquant^® Photometer NOVA 30 or
Cat.No. 109751 Spectroquant^® Photometer NOVA 60 or
Cat.No. 173632 Spectroquant^® Colorimeter Move 100
Cat.No. 114946 Rectangular cells 10 mm and/or
Cat.No. 114947 Rectangular cells 20 mm and/or
Cat.No. 114944 Rectangular cells 50 mm
Cat.No. 114548 Spectroquant^® Sulfate Cell Test
Cat.No. 100617 Spectroquant^® Sulfate Cell Test*
Cat.No. 114564 Spectroquant^® Sulfate Cell Test
Cat.No. 114791 Spectroquant^® Sulfate Test*
Cat.No. 106498 Sodium hydroxide for analysis
Cat.No. 100456 Nitric acid 65 % for analysis
Cat.No. 109535 MColorpHastTM Universal indicator strips pH 0 - 14
Cat.No. 116754 Water for analysis

*not compatible with Move 100

Differential analysis of sulfate soluble in hot water and total sulfate can be carried out with suitable sample preparation.

Sample preparation - hot water extraction:
Prepare a fine powder of the sample and dry at 105 °C. Mix 5 g with 100 mL of water for analysis and boil for
30 minutes on a hot plate. Allow to cool, transfer the suspension to a 200-mL volumetric flask and make up to the mark with water for analysis. Mix well, filter through a paper filter and then use as sample for the determination of water-soluble sulfate.

Sample preparation - total content:
Mix 100 mg of the finely powdered material along and 10 pellets of sodium hydroxide, place in a nickel crucible and heat for 30 minutes at 550 °C in a muffle furnace. Allow to cool and carefully add 10 mL water for analysis. If necessary, heat gently to obtain a suspension. Adjust to approximately pH 5 with nitric acid. Using water for analysis, transfer the suspension to a 100-mL volumetric flask, make up to the mark with water for analysis and mix well. Filter through a paper filter before carrying out the analysis.

Analysis:
Determine with the above mentioned test kits.

Calculation:
Sulfate (water-soluble) content in % = analysis value in mg/l x 0.004
Sulfate (total) content in % = analysis value in mg/l x 0.1