CADMIUM COPPERIZATION ASSAYS FOR THE PREPARATION OF NITRATE-REDUCING COLUMNS

An electrolytic method for the copperization of cadmium as a reducing agent for nitrate-nitrogen (NO3-N) determination is described. The con ditions, medium, and time of copperization as well as the length of th e cadmium reducing column has been studied in detail. This column was placed in a flow injection analyzer for the online determination of NO 3-N in soil extracts. The results obtained show that 1% copper sulfate (CuSO4), 30 min and 55 mm are the optimal medium, time, and column le ngth, respectively. With this reducing column, the method is linear be tween 0 and 12 ppm NO3--N with a precision of 0.29% and a sampling fre quency of 80 determinations per hour. The proposed method has been app lied to the determination of NO3--N in soil extracts and the results a gree with those obtained by the reference method (r = 0.9998). The opt imized electrolytic procedure for the copperization of cadmium permits more than 3000 determinations without any significant loss of sensiti vity.