Analytical Method: Zinc 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. 100861  Spectroquant^® Zinc Cell Test
Cat.No. 114566  Spectroquant^® Zinc 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 Indicator strips pH 0 - 6
Cat.No. 116754  Water for analysis
Charcoal activated for soil test

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 the 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 standard volumetric flask, finally fill up to volume with water for analysis and mix well.
 
Analysis:
Determine with the above mentioned test kits.
 
Calculation:
Zinc content in mg/kg Zn  =  analysis value in mg/l Zn x 20