On-line Determination of Total Nitrogen in Water by Microwave Digestion and Flow Injection-spectrophotometry

A rapid method for determination of total nitrogen in water by on-line microwave digestion and flow injection-spectrophotometry was established.Effects of concentration of reagents and other conditions were optimized.A detection limit of 0.04 mg/L total nitrogen is achieved.The relative standard deviation is 1.2% for the determination of a reference water sample of 0.491 mg/L total nitrogen(n=11).The proposed method is successfully applied to the analyses of several samples of river water,domestic wastewater and industrial wastewater,with relative standard deviations of less than 1.0% and recoveries of 97% to 101% by the standard addition method.