ISO 3357:1975 PDF

Name: ISO 3357:1975 — Sodium tripolyphosphate and sodium pyrophosphate for industrial use — Determination of total phosphorus(V) oxide content — Quinoline phosphomolybdate gravimetric method
SKU: ISO 3357:1975
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Sodium tripolyphosphate and sodium pyrophosphate for industrial use — Determination of total phosphorus(V) oxide content — Quinoline phosphomolybdate gravimetric method

Название (английский):

ISO 3357:1975

Sodium tripolyphosphate and sodium pyrophosphate for industrial use — Determination of total phosphorus(V) oxide content — Quinoline phosphomolybdate gravimetric method

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 3
Дата публикации:: 1 сентября 1975 г.
Издание:: ISO IS 3357 edition 1 version 1
ICS:: 71.060.50

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Описание (английский):

Based on hydrolysis of a test portion by prolonged boiling in the presence of hydrochloric acid. Precipitation of the phosphate ions in the form of quinoline phosphomolybdate in the presence of acetone. Filtration by means of a filter crucible, washing, drying and weighing of the precipitate.

Abstract

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Overview

ISO 3357:1975 specifies a gravimetric method for determining the total phosphorus(V) oxide content (expressed as P2O5) in sodium tripolyphosphate and sodium pyrophosphate for industrial use. First published in 1975, the method is based on acid hydrolysis of a test portion, precipitation of phosphate as quinoline phosphomolybdate, and gravimetric separation, drying and weighing of the precipitate.

Key topics and technical requirements

Principle: Hydrolyse the sample by prolonged boiling with hydrochloric acid to convert condensed phosphates to soluble phosphate ions. Precipitate phosphate as quinoline phosphomolybdate in the presence of acetone, then filter, wash, dry and weigh the precipitate.

Sample and aliquot: Typical test portion indicated is 1.00 g; an aliquot (25.0 ml) of the prepared solution is used for precipitation.

Reagents: Analytical-grade reagents only. Key reagents include hydrochloric acid (~38% w/w, ≈12 N), a citromolybdic reagent prepared from sodium molybdate and citric acid with nitric acid and quinoline, and acetone (flammable-use under ventilation).

Apparatus:

Fritted glass filter crucible, porosity P10 (pore diameter 4–10 µm).
Laboratory oven adjustable to 250 ± 10 °C.
Standard glassware for reflux and volumetric dilution.

Operating conditions:

Reflux hydrolysis of the sample for a minimum specified time (e.g., 20 minutes in the method).
Precipitation at controlled temperature (approx. 75 ± 5 °C) with a short hold (about 30 s).
Washing regime: multiple decantations and vacuum-assisted washes, then drying the crucible at 250 ± 10 °C for 15 minutes before weighing.

Calculation: The mass of quinoline phosphomolybdate precipitate (sample minus blank) is converted to % P2O5 using a conversion factor cited in the method (0.03207) and accounting for aliquot and sample masses.

Applications and users

Quality control laboratories at phosphate chemical producers, detergent manufacturers and additive suppliers.

Industrial analytical labs verifying P2O5 content in sodium tripolyphosphate (STPP) and sodium pyrophosphate (SPP) raw materials and finished products.

Regulatory and standards organizations requiring a standardized gravimetric reference method for total phosphorus(V) oxide determination.

Related standards

Annexed ISO publications referenced in the standard (useful for broader phosphate analysis):

ISO 2999 - Pyrophosphate (potentiometric evaluation)

ISO/R 859 - Tripolyphosphate: insoluble-in-water and pH methods

ISO 2998 - Orthophosphate (photometric molybdophosphate reduced)

ISO 3358 - Chromatographic separation and assay of phosphate forms

Keywords: ISO 3357:1975, sodium tripolyphosphate, sodium pyrophosphate, total phosphorus(V) oxide, P2O5, quinoline phosphomolybdate, gravimetric method, phosphate analysis, industrial QC.

ISO 3357:1975 PDF

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications and users

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ISO 3358:1976

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