Automated distillation-spectrophotometry procedure for determining ammonia in water

Abstract

The distillation pre-treatment step for ammonia analysis (0.003–0.500 mg l^–1 as nitrogen) was automated and coupled with an automated phenate-hypochlorite spectrophotometric step. Two buffers (phosphate, pH 7.4, and borate, pH 9.5) were evaluated as pH controls for the distillation step; with both buffers hydrolysis of 24 organic nitrogen compounds was less than 0.5% and the recoveries of added ammonia from solutions of 55 test compounds were at least 95%. The calibration for the system was linear; the rate of analysis was 20 samples per hour.