SIST EN 25663:1996

Water quality - Determination of Kjeldahl nitrogen - Method after mineralization with selenium (ISO 5663:1984)

Specifies a procedure for the determination of trivalent negative nitrogen. Organic nitrogen in the form of azide, azine, azo, hydrazone, nitrite, nitro, nitroso, oxime or semicarbazone is not determined quantitatively. The procedure is applicable to the analysis of raw, potable and waste waters.

Wasserbeschaffenheit - Bestimmung von Kjeldahl-Stickstoff - Verfahren nach Aufschluß mit Selen (ISO 5663:1984)

Qualité de l'eau - Dosage de l'azote Kjeldahl - Méthode apres minéralisation au sélénium (ISO 5663:1984)

1.1 Substance dosée La présente Norme internationale spécifie une méthode de dosage de l'azote par une méthode de type Kjeldahl. Seul l'azote à l'état trivalent négatif est dosé. L'azote organique du type azide, azine, azoïque, hydrazone, nitrite, nitré, nitrosé, oxime ou semicarbazone n'est pas dosé quantitativement. L'azote des composés hétérocycles peut être incomplètement récupéré. 1.2 Type d'échantillon La présente méthode est applicable aux eaux brutes, aux eaux potables et aux eaux résiduaires. 1.3 Étendue du dosage Une teneur en azote Kjeldahl, ρN jusqu'à 10 mg dans la prise d'essai peut être déterminée. Avec une prise d'essai de 10 ml, cela correspond à une concentration d'azote dans l'échantillon de ρN = 1 000 mg/l. 1.4 Limite de détection La limite de détection, déterminée expérimentalement (4 degrés de liberté), avec une prise d'essai de 100 ml est ρN = 1 mg/l. 1.5 Sensibilité Avec une

Kakovost vode - Določanje dušika po Kjeldahlu - Metoda po mineralizaciji s selenom (ISO 5663:1984)

General Information

• Status: Published
• Publication Date: 31-May-1996
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: KAV - Water quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jun-1996
• Due Date: 01-Jun-1996
• Completion Date: 01-Jun-1996
• Ref Project: EN 25663:1993 - Water quality - Determination of Kjeldahl nitrogen - Method after mineralization with selenium (ISO 5663:1984)

Relations

• Referred By: SIST EN 50438:2008 - Requirements for the connection of micro-generators in parallel with public low-voltage distribution networks
• Effective Date: 09-Feb-2026
• Referred By: SIST EN 13342:2001 - Characterization of sludges - Determination of Kjeldahl nitrogen
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 500-1:2007+A1:2010 - Mobile road construction machinery - Safety - Part 1: Common requirements
• Effective Date: 28-Jan-2026

Overview

SIST EN 25663:1996 establishes a standardized procedure for the determination of Kjeldahl nitrogen in water samples, following mineralization with selenium. Published by the Slovenski inštitut za standardizacijo (SIST), this standard aligns with ISO 5663:1984 and provides a reliable method for assessing water quality in a variety of environments. The determination of trivalent negative nitrogen is critical for water quality monitoring, regulatory compliance, and pollution assessment.

Key Topics

• Kjeldahl Nitrogen Analysis: The method specified in SIST EN 25663:1996 focuses on measuring trivalent negative nitrogen, typically present as ammonia or organically bound nitrogen. The procedure excludes certain organic nitrogen forms, such as azide, azine, azo, hydrazone, nitrite, nitro, nitroso, oxime, or semicarbazone.
• Selenium Mineralization: Selenium acts as a catalyst during the digested breakdown of nitrogen-containing compounds, enhancing the conversion efficiency and accuracy in the Kjeldahl process.
• Exclusions and Limitations: Not all nitrogen species are quantified with this method. Nitrogen forms not convertible under standard digestion (as listed above) are not fully detected, which is vital for accurate data interpretation.
• Applicable Water Types: The procedure is valid for the analysis of raw, potable (drinking), and waste waters, making it broadly useful for routine water quality assessments.

Applications

SIST EN 25663:1996 is widely applied in areas where water quality monitoring and regulatory analysis are essential. Key uses include:

• Drinking Water Testing: Ensuring compliance with safety standards by determining the presence of Kjeldahl nitrogen compounds in drinking water.
• Wastewater Treatment Monitoring: Evaluating nitrogen removal efficiency in treatment plants by quantifying ammonia and organic nitrogen in effluents.
• Surface and Groundwater Assessments: Tracking nutrient levels in rivers, lakes, and aquifers for environmental monitoring and policy development.
• Industrial Effluent Analysis: Monitoring discharges from manufacturing or agricultural facilities to ensure adherence to environmental protection requirements.

Organizations responsible for environmental regulation, public health, water treatment, and laboratory testing benefit from consistent implementation of this method. The use of standardized procedures improves data comparability across laboratories and regions.

Related Standards

For comprehensive water quality assessment and laboratory analysis, the following standards are often referenced alongside SIST EN 25663:1996:

• ISO 5663:1984: International counterpart detailing the determination of Kjeldahl nitrogen with selenium mineralization.
• EN 25663:1993: European standard equivalent to SIST EN 25663:1996, ensuring harmonized practices across Europe.
• ISO 11905-1: Determination of nitrogen - Part 1: Inorganic and organic nitrogen compounds by oxidation and subsequent photometric determination.
• ISO 6878: Water quality - Determination of phosphorus - Ammonium molybdate spectrometric method.
• ISO 7150: Water quality - Determination of ammonium.

Adhering to SIST EN 25663:1996 improves the consistency, accuracy, and reliability of Kjeldahl nitrogen measurements, supporting effective water management and environmental protection initiatives.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Bestimmung von Kjeldahl-Stickstoff - Verfahren nach Aufschluß mit Selen (ISO 5663:1984)Qualité de l'eau - Dosage de l'azote Kjeldahl - Méthode apres minéralisation au sélénium (ISO 5663:1984)Water quality - Determination of Kjeldahl nitrogen - Method after mineralization wi
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