PROCEDURE for test ( STEP WISE ):

1. 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.
2. Add 1-2 drops of  RXSOL TK5 and mix with the stirring rod , to obtain ORANGE / light reddish  colour. 
3. 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 Number of DROPS of TK6}