The Fertilisers (Sampling and Analysis) Regulations 1991 No. 973

SCHEDULE 2 METHODS OF ANALYSIS

PART I

12a. DETERMINATION OF WATER-SOLUBLE MAGNESIUM—ATOMIC ABSORPTION SPECTROPHOTOMETRIC METHOD

REAGENTS

4.—4.1 Hydrochloric acid, N solution (approximately).

4.2 Hydrochloric acid, 0.5 N solution.

4.3 Magnesium standard solution: dissolve 1.013 g magnesium sulphate (MgSO₄.7H₂O) in 0.5 N hydrochloric acid solution (4.2) and dilute to 100 ml with this acid.

• 1 ml of this solution contains 1 mg of magnesium (Mg).

• or

• weigh out 1.658 g of magnesium oxide, previously calcined at 600° for 2 hours, place in a beaker with 100 ml of water and 120 ml of approximately N hydrochloric acid (4.1). After dissolution, transfer quantitively into a one litre graduated flask, make up the volume with water and mix.

• 1 ml of this solution contains 1 mg of magnesium (Mg).

4.4 Strontium chloride solution: dissolve 15 g strontium chloride (SrCl₂.6H₂O) in 0.5 N hydrochloric acid solution (4.2) and dilute to 100 ml with the same solvent.