Analytical Method: Sulfite in apples treated with sulfite

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. 114394  Spectroquant® Sulfite Cell Test
Cat.No. 101746  Spectroquant® Sulfite Test
Cat.No. 109137  Sodium hydroxide solution 1 mol/l
Cat.No. 109533  MColorpHastTM pH-indicator strips pH 5 - 10
Cat.No. 116754  Water for analysis 
Membrane filter with 0.45 μm pore diameter
 
Sample preparation:
Chop exactly 100 g of the drained raw material in cooked and oxygen-free water for analysis with a mixer. Transfer the apple puree in a 1-l volumetric flask and fill up to volume with cooked, oxygen-free water for analysis. Stir the suspension in the closed vessel for 30 minutes with a magnetic stirrer. Filter off the solid parts through a folded filter.
Take 50 ml of the filtrate and adjust the pH value to 5 - 8 by using sodium hydroxide 1 mol/l (check with pH-indicator strips). Transfer this solution into a 100-ml volumetric flask and fill up to volume.
Attention! The sample should be prepared quickly to avoid any contact to the air.
 
Analysis:
Determine with the above mentioned test kits.
 
Calculation:
Sulfite content in mg/kg SO3 = analysis result in mg/l SO3 x 20

Materials

     
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