How to Use Dinitrosalicylic Acid

Dinitrosalicylic acid (D.N.S.A. or 3:5-dinitrosalicylic acid) is a reagent used to determine sugar content especially glucose. The DNS technique is employed in order to estimate sugar present in the blood, in the cerebrospinal fluid and in other human bodily fluids. This is also effectively used in the handling of requirements for diabetic clinics in hospital laboratories, considering that only 10 minutes is enough for the process to take place and the reagents are stable, cheap and easily prepared. The amount of blood sugar in the blood has metabolic implications and is used to determine the presence of blood sugar-related disorders such as hyperglycemia. One good way to assess blood sugar level is through the use of dinitrosalicylic acid.

Things You'll Need

• 3:5 dinitrosalicylic acid (17.5 g)
• 60C hot distilled water (1000 ml)
• Filter paper
• Funnel
• 1 percent standard glucose solution in saturated benzoic acid
• Stoppered container (greater than 100 ml)
• Phenol (13.8 g)
• Sodium bisulfite (13.8 g)
• 10 percent sodium hydroxide solution (350 ml)
• Potassium-sodium-tartrate (510 ml)
• Water with normal temperature (180 ml)
• Pipettes (0.1 or 0.2 ml)
• Boiling water-bath
• Laboratory equipment for heating
• Laboratory equipment for measuring small solids and liquids

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Instructions

Instructions

• 1

  Place 17.5 g of 3:5-dinitrosalicylic acid in 1,000 ml of hot distilled water (around 60C) and stir to dissolve. Filter the solution through a filter paper and funnel and store at 25C. This is referred to later as Lee's Reagent A.

• 2

  Prepare Glucose-D.N.S.A. solution by adding 1 percent glucose in saturated benzoic acid solution to 100 ml of 1.75 percent Lee's Reagent A and mix thoroughly by inverting the stoppered container repeatedly. Store at 25C.

• 3

  Dissolve 13.8 g of phenol and 13.8 g of sodium bisulfite in 350 ml of 10 percent sodium hydroxide. Add this solution to 510 g of potassium-sodium-tartrate in 180 ml of water. Filter the final solution through filter paper. Store at room temperature. This will serve as Lee's Reagent B.

• 4

  Obtain blood from a capillary puncture using ordinary 0.1 or 0.2 ml pipettes. The 0.1 ml pipette is more qualitatively accurate than the latter when measuring 0.1 ml of blood. However the reverse is true when measuring 0.2 ml of blood.

• 5

  Deliver the blood in the pipette into the glucose-D.N.S.A. solution in a test tube. Mix it in the proportion 1:20. Draw the pipette up and down until you get an even distribution of the mixture between the test tube and the pipette. Leave the pipette in the solution and remove the precipitate from the pipette after it has settled an hour or two later.

• 6

  Add an equal volume of Lee's Reagent B to the clear supernatant. After which, heat in a boiling water-bath for not less than three minutes.

• 7

  Compare the red color developed with one produced by a standard glucose solution.