Paragraph 4 REAGENTS

Sulfuric acid solution, approximately 1M

4.1

Carefully pour 55 ml of sulfuric acid (H₂SO₄, ρ = 1.84 g/ml) into a 1 litre volumetric flask containing 800 ml of water. Mix. After cooling, make up to one litre. Mix again.

Diluted ammonia solution (1:3)

4.2

Mix 1 volume of concentrated ammonia solution (NH₄OH, ρ = 0.9 g/ml) with 3 volumes of water.

Diluted acetic acid solution (1:3)

4.3

Mix 1 volume of concentrated acetic acid (99.7% CH₃COOH, ρ = 1.049 g/ml) with 3 volumes of water.

Solution of disodium salt of ethylene diamine tetraacetic acid (EDTA)

4.4

Dissolve 5 g of Na₂EDTA in water in a 100 ml volumetric flask. Make up to the calibration mark and mix.

Buffer solution

4.5

In a 100 ml volumetric flask, dissolve 15 ml of concentrated acetic acid and 30 g of ammonium acetate in water. Make up to 100 ml.

8-hydroxyquinoline (oxine) solution

4.6

In a 100 ml volumetric flask dissolve 3 g of 8-hydroxyquinoline in 5 ml of concentrated acetic acid. Add 80 ml of water. Add the ammonia solution (4.2) drop by drop until the solution becomes cloudy and then add the acetic acid (4.3) until the solution becomes clear again.

Make up to 100 ml with water.