ISO 25475:2016 PDF

Name: ISO 25475:2016 — Fertilizers — Determination of ammoniacal nitrogen
SKU: ISO 25475:2016
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Fertilizers — Determination of ammoniacal nitrogen

Название (английский):

ISO 25475:2016

Fertilizers — Determination of ammoniacal nitrogen

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 12
Дата публикации:: 7 апреля 2016 г.
Издание:: ISO IS 25475 edition 1 version 1
ICS:: 65.080

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Описание (английский):

ISO 25475:2016 specifies a method for the determination of the ammoniacal nitrogen content in fertilizers. The method is applicable to all nitrogenous fertilizers including compound fertilizers, in which nitrogen is found exclusively either in the form of ammonium salts or ammonium salts together with nitrates. ISO 25475:2016 is not applicable to fertilizers containing urea, cyanamide or other organic nitrogenous compounds.

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview

ISO 25475:2016 specifies a laboratory method for the determination of ammoniacal nitrogen in fertilizers. The procedure applies to nitrogenous and compound fertilizers where nitrogen is present as ammonium salts or as ammonium salts together with nitrates. It is explicitly not applicable to fertilizers containing urea, cyanamide or other organic nitrogenous compounds. The method uses base-induced displacement of ammonia, steam distillation, capture in a standard acid and back-titration to quantify ammoniacal nitrogen.

Key topics and technical requirements

Principle: Conversion of ammonium to ammonia by excess NaOH, distillation of liberated NH3, absorption into standard H2SO4 (or alternative acids), and back-titration of excess acid with standard NaOH/KOH.

Scope/limitations: Valid for fertilizers where nitrogen is exclusively inorganic (ammonium ± nitrate); excludes organic-N fertilizers (urea, cyanamide).

Reagents: Analytical-grade reagents and CO2- and nitrogen-free water (ISO 3696 grade 3). Specified solutions include diluted HCl, standard H2SO4 (various molarities depending on variant), carbonate-free NaOH/KOH titrants, 30% NaOH for sample dissolution, and indicators (mixed methyl red/methylene blue or methyl red).

Apparatus: Borosilicate steam distillation setups (several illustrated configurations), rotary shaker (35–40 r/min), volumetric glassware and pipettes, anti-bumping granules. Automatic distillation apparatus permitted if results are statistically equivalent.

Procedure highlights: Weigh prepared sample (typical quantities 5–10 g), extract with HCl and water, shake and filter to 500 ml, distil an aliquot with NaOH added, collect ~250 ml distillate, titrate residual acid. Tables in the standard (Table 1–3) define weighing/dilution/aliquot choices and calculation factors for different N ranges.

Quality controls: Blank and control tests, specified precision data (repeatability, reproducibility, inter-laboratory test results) and reporting requirements.

Applications and users

ISO 25475:2016 is used by:

Fertilizer manufacturers - production quality control and batch verification.

Analytical testing laboratories - routine analysis to verify ammoniacal N content for specification compliance.

Regulatory and inspection bodies - enforcement of fertilizer labeling and trade requirements.

Research and agronomy labs - formulation studies and fertilizer behavior investigations.

Practical benefits include reliable, standardized measurement of ammoniacal nitrogen for product specification, safety data, and trade conformity.

Related standards

ISO 3696 - Water for analytical laboratory use

ISO 14820-2 - Fertilizers - Sampling and sample preparation - Part 2

ISO 14820-1 (recommended for sampling)

EN 12944-1 / EN 12944-2 - Fertilizer vocabulary referenced for terms

Keywords: ISO 25475:2016, ammoniacal nitrogen, fertilizer analysis, ammonia distillation, titration, ammonium salts, laboratory method.

ISO 25475:2016 PDF

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications and users

Related standards

Технические детали

SIST EN ISO 3696:1998

Water for analytical laboratory use - Specification and test methods (ISO 3696:1987)

ISO 14820-2:2016

Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample preparation

ISO 14820-1:2016

Fertilizers and liming materials — Sampling and sample preparation — Part 1: Sampling