Analytical Method: Nitrite in potato instant powder

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. 114547  Spectroquant^® Nitrite Cell Test
Cat.No. 114776  Spectroquant^® Nitrite Test
Cat.No. 119899  Nitrite standard solution ready to use, 1000 mg/l Nitrite
Cat.No. 104874  Potassium hydrogenphthalate for analysis
Cat.No. 116754  Water for analysis
Membrane filter 0.45 μm pore diameter
 
Potassium hydrogenphthalate solution 2%:
Dissolve 2 g potassium hydrogenphthalate in 100 ml of water for analysis.
 
Sample preparation:
In a closed Schliff-Erlenmeyer flask stir 5 g of the finely ground sample with 95 ml water for analysis and 5 ml potassium hydrogenphthalate solution 2% for 30 minutes. Then separate the suspension in the centrifuge at 4000 turns per minute for 15 minutes. Filter the supernatant solution through a folded filter. If the resulting solution is not clear, additionally filter it through a membrane filter (mesh 0.45 μm).
 
Analysis:
Determine with the above mentioned test kits.
For the determination of the influence by the matrix it is necessary to run along a samples with standard addition.
 
Calculation:
Nitrite content in mg/kg NO₂ = analysis value in mg/l NO₂ x 20