BS EN 12947:2000 – Liming materials Ð Determination of magnesium content Ð Atomic absorption spectrometric method
1 Scope
This European Standard specifies a method for the determination of the magnesium content of all liming materials by atomic absorption spectrometry.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
EN 1 482, Sampling of solid fertilizers and liming materials.
ISO 331 0-1 , Test sieves – Technical requirement and testing – Part 1: Test sieves of metal wire cloth.
3 Principle
Dissolution of the test portion in diluted hydrochloric acid. Filtration and dilution. Determination of magnesium by flame atomic absorption spectrometry at a wavelength of 285,2 nm.
4 Reagents
4.1 General
Commercially available standard solutions may be used instead of standard solutions produced on-site in the laboratory.
4.2 Hydrochloric acid solution, diluted
Dilute 500 ml of concentrated hydrochloric acid (p 20 = 1 ,1 8 g/ml) to 1 000 ml with water.
4.3 Hydrochloric acid solution
Approximately c(HCl) 1 mol/l
4.4 Hydrochloric acid solution
Approximately c(HCl) 0,5 mol/l
4.5 Standard magnesium solution
Containing 1 ,000 g of magnesium per litre.
4.5.1 Weigh 1 ,01 3 g of magnesium sulfate (MgSO 4
• 7H 2 O) into a 1 00 ml volumetric flask, dissolve in
hydrochloric acid solution (4.4) and dilute to the mark with the same solution.
or
4.5.2 Heat magnesium oxide (MgO) at 600 °C for 2 h. Weigh 1 ,658 g of the freshly calcined MgO into a 500 ml beaker, dissolve in 1 00 ml of water and 1 20 ml of hydrochloric acid solution (4.3). Transfer quantitatively the solution to a 1 000 ml volumetric flask, dilute to the mark with water and mix thoroughly.