Total nitrogen in wastewater analysis: Comparison of Devarda’s alloy method and high temperature oxidation followed by chemiluminescence detection

Abstract

Two methods for determining total nitrogen (TN) contents of complex wastewaters were compared: Devarda’s alloy method and a method involving high temperature oxidation (HTO) followed by chemiluminescence detection (CLD). In the latter multiple standard additions were used for quantification purposes since the CLD response was found to be dependent on the structure of the analysed nitrogen-containing compounds. For both methods, sample dilution steps were necessary to achieve acceptable accuracy. The accuracies for selected compounds used in tests were within the 65–105% range. In a long-term interlaboratory investigation the HTO-CLD method yielded significantly (p < 0.05) higher results than Devarda’s alloy method and greater precision (within-assay repeatability approximately 1% RSD, while the corresponding within-day repeatability for Devarda’s alloy method was approximately 7% RSD).