PROCEDURE for test ( STEP WISE ):
Measure 1 ml of SAMPLE WATER in graduated TEST TUBE / CYLINDER , with the help of syringe / pippet and diluted with Distilled Water up to 10 ml.
Add 1-2 drops of RXSOL TK5 and mix with the stirring rod , to obtain ORANGE / light reddish colour.
Add RXSOL TK6 drop by drop , mixing with the stirring rod until For endpoint ORANGE to BLUE / GREENISH colour just appears / develop.
Each DROPS is equivalent to 50 PPM of NO2
CALCULATION : 50 X…..