DETERMINATION OF NITRITES IN THE WATER THROUGH RAPID DETERMINATION
Objectives
Determine the presence of nitrites in water samples
Materials
Gloves and personal protective equipment
Kit for the determination of nitrite
2 Tubes per sample of water
Water samples
5 ml syringe or pipette
Reaction
Measurement of the intensity of the red-fuchsia colour formed by reaction of nitrous ion with sulphanilic acid and naphthylamine in an acidic environment.
Procedure
Respect security measures.
Shake the sample to homogenise.
Rinse the syringe (or pipette) and tubes with the water to be analysed.
Withdraw 5 ml of water to be analysed using the syringe (or pipette) and place it in each of the two tubes.
Place a test tube (blank test) in the left hole of the comparator.
Place the comparator on the colour scale with the coloured fields under the blank test piece.
In the second test tube add 8 drops of reagent A and shake well.
After 10 minutes, place the test tube with the reagents in the right hole of the comparator.
Observe from above and slide the comparator until you find the colour of the sample.
Read the corresponding value, indicated by the comparator arrow.
If the concentration is high dilute the sample and determine the value taking into account the dilutions
Expected results
The presence of nitrates determines the colouring of the sample
The colour scale is used to determine the value of nitrites present expressed in parts per million (ppm) or milligrams per litre (mg/l).
The more coloured the sample, the higher the nitrite content in the water.
Values above 0. 5 mg/l indicate waters with nitrogen pollution problems.
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