ISO 10048-1991 PDF

Full title and description

ISO 10048:1991 — Water quality — Determination of nitrogen — Catalytic digestion after reduction with Devarda's alloy. Specifies a laboratory procedure for determining total nitrogen (as ammonium, nitrite, nitrate and organic nitrogen convertible to ammonium) in water by catalytic digestion following reduction with Devarda’s alloy.

Abstract

This International Standard describes the principle, apparatus, reagents, test procedure, expression of results and required test report content for the catalytic digestion method (Devarda’s alloy reduction) used to convert nitrogenous species to ammonium, followed by distillation and quantitative determination (titrimetric or spectrophotometric). The method is intended for raw and polluted waters and gives operational details and recovery information for various nitrogen-containing compounds.

General information

• Status: Withdrawn.
• Publication date: October 1991 (Edition 1).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.060.50 (Water quality — examination of water for chemical substances).
• Edition / version: Edition 1, 1991.
• Number of pages: 5 pages.

Scope

Specifies a method for the determination of nitrogen present in water samples in the forms of ammonium, nitrite, nitrate and organic nitrogen compounds that can be converted to ammonium under the method conditions. Applicable to analyses of raw and polluted waters; nominal analytical range given in the standard is up to about 200 mg/l nitrogen (extendable by using smaller test portions). The procedure covers reduction (Devarda’s alloy), catalytic digestion, conversion to ammonium sulfate, alkaline distillation into boric acid and subsequent determination by titration or spectrophotometry.

Key topics and requirements

• Principle: reduction with Devarda’s alloy followed by catalytic digestion and conversion to ammonium for distillation and measurement.
• Applicable sample types: raw, polluted and similar water matrices where targeted nitrogen species are present.
• Reagents: Devarda’s alloy (approx. Al–Cu–Zn), strong acids (sulfuric), potassium sulfate to raise boiling point, boric acid indicator solution, and standard acid for titration.
• Apparatus: Kjeldahl flasks (100–250 ml), heating mantle or block capable of high temperature, distillation setup, volumetric glassware and spectrophotometer where applicable.
• Range & sensitivity: typical working range up to ~200 mg/l N (can be adjusted by sample size); method performance and recoveries are discussed for different organic nitrogen compounds.
• Expression of results and reporting requirements: calculation of nitrogen concentration, test conditions, test portion size, detection/quantitation technique (titration or spectrophotometry) and any deviations from the procedure.

Typical use and users

Used by environmental and water-quality laboratories, regulatory testing bodies, research laboratories and consultants performing routine or investigative analyses of surface water, wastewater and industrial effluents where determination of combined inorganic and organic nitrogen is required. The method historically served as an alternative digestion/reduction route alongside Kjeldahl-type methods.

Related standards

Normative and related standards include ISO 7150-1 (determination of ammonium in water) which is referenced in the ISO 10048 text, and other Kjeldahl-related standards such as ISO 5663 (Kjeldahl nitrogen after mineralization with selenium) and national water-quality methods addressing total or Kjeldahl nitrogen. Users should consult current ISO/TC 147 deliverables for the preferred contemporary methods, since ISO 10048:1991 has been withdrawn.

Keywords

Water quality; nitrogen determination; Devarda’s alloy; catalytic digestion; Kjeldahl; total nitrogen; distillation; titration; spectrophotometry.

FAQ

Q: What is this standard?

A: ISO 10048:1991 is an International Standard that specified a laboratory method for determining nitrogen in water by catalytic digestion after reduction with Devarda’s alloy.

Q: What does it cover?

A: It covers the principle, reagents, apparatus, step‑by‑step procedure, calculation and reporting for converting various nitrogen forms to ammonium (via Devarda’s reduction and catalytic digestion), distilling the liberated ammonia into boric acid and determining it by titration or spectrophotometry. The method includes guidance on recoveries for different organic nitrogen compounds.

Q: Who typically uses it?

A: Environmental, municipal and industrial water‑testing laboratories, regulatory agencies and researchers concerned with total nitrogen or combined forms of nitrogen in water samples.

Q: Is it current or superseded?

A: ISO 10048:1991 has been withdrawn (the ISO catalogue lists it as withdrawn). Some national bodies note withdrawal dates (for example, withdrawal listed on national catalogues in 2016) and laboratories now commonly use other established methods (e.g., Kjeldahl-type procedures or modern instrumental methods) depending on regulatory and analytical needs. Check your national standards body or ISO for the currently recommended methods.

Q: Is it part of a series?

A: It was developed under ISO/TC 147 (Water quality), Sub‑Committee SC 2 (physical, chemical and biochemical methods). It relates to other water‑quality nitrogen methods (ISO 7150 series, ISO 5663 and other Kjeldahl/total nitrogen standards) rather than being a numbered multi‑part series.

Q: What are the key keywords?

A: Devarda’s alloy; catalytic digestion; total nitrogen; water quality; Kjeldahl; distillation; titration; spectrophotometry.