Analytical Method: Magnesium in soils

Instruments 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. 100815  Spectroquant® Magnesium Cell Test
Cat.No. 100316  Hydrochloric acid 25 % for analysis
Cat.No. 109970  Hydrochloric acid 1 mol/l for analysis
Cat.No. 105588  Sodium hydroxide solution 10 % for analysis
Cat.No. 109535  MColorpHastTM Universal Indicator strips pH 0 - 14
Cat.No. 109531  MColorpHastTM pH-indicator strips pH 0 - 6
Cat.No. 116754  Water for analysis
Charcoal activated for soil test
Folded filter

Sample preparation:
In a glass beaker place 10 g of air-dried and sieved (mesh 2 mm) sample with 100 ml hydrochloric acid 1 mol/l and a spatula-tipfull of charcoal activated for soil tests and mix well for 1 hour. The pH-value should be 1 - 2 (check with pH-indicator strips). If necessary, adjust with hydrochloric acid 25 %.

Afterwards adjust the pH value of the suspension to 3.0 with sodium hydroxide solution 10 %, using a pH meter. Then remove the undissolved matter by filtration through a folded filter and wash the filter residues 3 times with water for analysis. Collect the filtrate and the washings in a 200-ml volumetric flask, finally fill up to volume with water for analysis and mix well.
Determine with the above mentioned test kit.
Magnesium content in mg/kg Mg = analysis value in mg/l Mg x 20


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