T/ZJATA 0025-2024 Water quality determination of total nitrogen using pre-prepared colorimetric reagent spectrophotometry

Scope

Scope: This document describes the spectrophotometric method using a pre-prepared colorimetric acid reagent for determining total nitrogen in water. This document is applicable to the determination of total nitrogen in groundwater, domestic sewage, and industrial wastewater. The method's detection limit is 1.0 mg/L, the lower limit of determination is 4.0 mg/L, and the upper limit of determination for undiluted water samples is 100 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 a method of pre-prepared reagents for dissolved nitrogen in samples, nitrogen in suspended matter, and total nitrogen. In a system of potassium persulfate and alkaline medium, after high-temperature digestion, nitrate and colorimetric acid form a yellow complex in a strong acid medium, and the total nitrogen value is determined by spectrophotometry. This method has the following advantages: 1) Reducing the amount of water samples and reagents, and reducing the discharge of wastewater; 2) Using pre-prepared reagents to reduce the impact of harmful substances on human health during reagent preparation; 3) The instrument comes with built-in curves, and the water sample concentration is directly displayed after colorimetry, which saves the time of curve preparation and result calculation, improves analysis efficiency, and reduces work intensity; 4) Compared with traditional colorimetric tubes and spectrophotometers, pre-prepared reagent tubes and portable photometers are smaller in size and more portable, suitable for outdoor detection and on-site detection. They are a powerful supplement to the existing analysis standard method system and have certain innovation

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