Ohotolidine test is used to determine-
Nitrates in water
Nitrites chlorine in water
Free and combined chlorine in water
Ammonia content in water
Oho-toluidine test is used to determine both free and residual chlorine with speed and accuracy. It is done using oho-toluidine dissolved in 10 per cent solution of hydrochloric acid. When added to water containing chlorine it turns yellow and its intensity varies with the concentration of the gas. Oho-toluidine Arsenite test is used to determine free and residual chlorine separately. (PARK TB (25th edition pg 775)
Environment and health