Analytical Method: Iron in fertilizers

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. 114549  Spectroquant® Iron Cell Test
Cat.No. 114896  Spectroquant® Iron Cell Test*
Cat.No. 114761  Spectroquant® Iron Test
Cat.No. 100796  Spectroquant® Iron Test
Cat.No. 105063  Potassium nitrate for analysis
Cat.No. 106498  Sodium hydroxide for analysis
Cat.No. 100519  Perchloric acid 70 % for analysis
Cat.No. 109137  Sodium hydroxide solution 1 mol/l
Cat.No. 109531  MColorpHastTM pH-indicator strips pH 0 - 6
Cat.No. 116754  Water for analysis
*not compatible with Move 100
Sample preparation:
Heat 150 - 200 mg of very finely powdered sample material at 900 °C for 15 minutes, in a nickel crucible, in order to remove any organic matter.
After cooling, mix the residue with 0.3 g of potassium nitrate and 1.5 g of sodium hydroxide and heat by means of a Bunsen burner, for 5 minutes, to a dull red heat. After cooling, dissolve the frit in 50 ml of water for analysis, with warming. Then transfer the solution into a 150-ml glass beaker, which contains 10 ml water for analysis and 5 ml perchloric acid 70 %. Adjust the pH value to 3, with 1 mol/l sodium hydroxide solution, check the value with pH Indicator strips. Transfer the solution to a 100-ml volumetric flask, fill to the mark with water for analysis and mix well.
Determine with the above mentioned test kits.
Iron content in % = analysis value in mg/l Fe x 100

                                weight of sample in mg


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