Photometric determination of ammonium nitrogen with the nessler reagent in drinking water after its chlorination

The photometric procedure for determining ammonium nitrogen in the drinking water containing inorganic chloramines has been refined. The preliminary reduction of chloramines at pH 4–9 was performed by using sodium sulfite at the fixed concentration in the interval 0.1–0.2 mM. Thereafter the mixture of solutions K 2 HgI 4 (1–2 mM) and NaOH (80–100 mM) was added and the optical density of the resultant colored solution was measured at 440 and 600 nm.