Park and Johnson Method for a Reducing Sugar

This method for determining reducing sugars (7) is based on the reduction of ferricyanide ions in alkaline solution by a reducing sugar. The ferrocyanide produced can then react with a second mole of ferricyanide producing the ferric-ferrocyanide (Prussian blue) complex. Potassium 

Prepare reagent A by dissolving 0.5 g potassium ferricyanide in 1000 ml distilled water. This solution should be stored in a brown bottle. 2-50. Prepare reagent B by dissolving 5.3 g sodium carbonate and 0.65 g potassium cyanide in 1000 ml distilled water. 

Prepare reagent C by dissolving 1.5 g ferric ammonium sulfate and 1.0 g sodium dodecyl sulfate in 1000 ml 0.05 N sulfuric acid (1.4 ml concentrated sulfuric acid per liter). 

Add an appropriate amount of distilled water to each tube to give a final volume of 1.0 ml. 

0 ml solution B and then 1.0 ml solution A to the sample tubes. DO NOT MOUTH-PIPETTE THESE SOLUTIONS. 

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