T/ZJATA 0024-2024 Water Quality Determination of Ammonia Nitrogen by Prepared Nessler's Reagent Spectrophotometry Method

Scope

Scope: This document describes the spectrophotometric method using pre-prepared reagents to determine ammonia nitrogen in water. This document is applicable to the determination of ammonia nitrogen in surface water, groundwater, domestic sewage, and industrial wastewater. When using the low-range determination method, the detection limit of this method is 0.20 mg/L, the lower limit of determination is 0.80 mg/L, and the upper limit of determination for undiluted water samples is 30.0 mg/L. When using the high-range determination method, the detection limit of this method is 1.50 mg/L, the lower limit of determination is 6.00 mg/L, and the upper limit of determination for undiluted water samples is 150 mg/L. Main technical content: The standard includes the method principle, instrumentation and equipment, reagents or materials, samples, detection steps, quality control, etc. It establishes that ammonia nitrogen, which exists in the form of free ammonia or ammonium ions, reacts with Nessler's reagent to form a light red-brown complex. The absorbance of the complex is proportional to the ammonia nitrogen content, and the absorbance is measured at a wavelength of 420 nm. This method is based on the coloration principle of Nessler's reagent and is improved on the basis of HJ 535-2009. It uses pre-prepared reagents to determine ammonia nitrogen, which has the following advantages: 1) Reduce the amount of water samples and reagents taken, and reduce the amount of wastewater discharged; 2) Use ready-made Nessler's reagent to reduce the impact of harmful substances on human health during the preparation of reagents; 3) The instrument comes with built-in curves, and the water sample concentration is directly displayed after colorimetry, eliminating the time required for curve preparation and result calculation, and improving the analysis efficiency; 4) Compared with traditional colorimetric tubes and spectrophotometers, pre-prepared reagent tubes and portable photometers are

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