First National Standard for On-Site Ammonia Nitrogen Determination Officially Implemented

Effective May 1, 2026, HJ 1448-2026 "Water Quality — Determination of Ammonia Nitrogen — Nessler's Reagent — Portable Photometric Method", approved and issued by the Ministry of Ecology and Environment, officially comes into effect. This is China's first national ecological environment standard for portable on-site determination of ammonia nitrogen, providing a unified technical basis for pollution source tracing, water quality trend investigation, and preliminary compliance assessment.

As a domestic instrument manufacturer with over eighty years of dedication to the field of water quality analysis, LeiCi (RAYMAGNETIC) has always advanced in step with national monitoring standards. After item-by-item verification, the LeiCi DGB-401 multi-parameter water quality analyzer (2026 edition) fully meets the technical and quality control requirements of HJ 1448-2026. This article is divided into two parts: the first systematically interprets the new standard, and the second presents the DGB-401's compliance item by item.

For a long time, there has been no unified national standard for rapid on-site determination of ammonia nitrogen. On-site emergency response, source tracing, and related work were mostly conducted with reference to the laboratory method HJ 535-2009 "Water Quality — Determination of Ammonia Nitrogen — Nessler's Reagent Spectrophotometry", which has limitations such as cumbersome procedures, long processing times, and inability to obtain results immediately on site. HJ 1448-2026 was approved and issued by the Ministry of Ecology and Environment on January 20, 2026, and takes effect on May 1, 2026, filling the standard gap in portable on-site ammonia nitrogen monitoring. It marks the transition of ammonia nitrogen monitoring from a "laboratory precise testing" model to a dual-track model of "laboratory + rapid on-site screening", further improving the water quality monitoring standard system.

The standard specifies the Nessler's reagent — portable photometric method for the determination of ammonia nitrogen in water, applicable to the following on-site determinations of ammonia nitrogen in surface water, groundwater, domestic sewage, and industrial wastewater:

Standard positioning note: This standard is a rapid on-site screening method; data obtained are suitable for preliminary judgment, source tracing, trend analysis, and similar purposes. For compliance reporting, acceptance, or arbitration, verification should be performed in combination with laboratory methods such as HJ 535.

III. Comparison of HJ 1448-2026 and HJ 535-2009

0, 0.1, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0 mg/L

0, 0.5, 1.0, 1.5, 2.0, 4.0 mg/L

Visible spectrophotometer (20 mm cuvette), distillation apparatus, etc.; requires a fixed laboratory

Portable photometer integrating optical measurement, automatic calculation, and data storage; waterproof and dustproof

Before on-site determination, test papers such as pH test paper, residual chlorine test paper, and total hardness test paper should be used for preliminary identification of interferences, which should then be eliminated as follows:

Filter through a 0.45 μm membrane and discard the first approximately 2 mL of filtrate