ISO 456:1973

Name: ISO 456:1973 — Surface active agents — Analysis of soaps — Determination of free caustic alkali
SKU: ISO 456:1973
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Surface active agents — Analysis of soaps — Determination of free caustic alkali

Название (английский):

ISO 456:1973

Surface active agents — Analysis of soaps — Determination of free caustic alkali

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 5
Дата публикации:: 1 марта 1973 г.
Издание:: ISO IS 456 edition 1 version 1
ICS:: 71.100.40

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Описание (английский):

The determination may be carried out in two different ways by the ethanol method or the barium chloride method. In the first case the soap is dissolved in neutralized ethanol, and the free caustic alkali is titrated with an ewthanol solution of hydrochloric acid. The second way includes precipitating of soap and carbonate with barium chloride and determining of the residual alkalinity of the solution, representing the alkalinity of the free potassium hydroxide.

Abstract

Похожие стандарты

Другие стандарты ISO

Overview

ISO 456:1973 - "Surface active agents - Analysis of soaps - Determination of free caustic alkali" specifies two validated laboratory methods for measuring free caustic alkali in commercial soaps. The standard covers scope, reagents, apparatus, stepwise procedures and expression of results for the ethanol (Method A) and barium chloride (Method B) techniques. It applies to ordinary commercial soaps (not compounded products) and was published by ISO/TC 91 in 1973.

Key topics and technical requirements

Two alternative methods

Method A (Ethanol method): dissolve soap in neutralized absolute ethanol, remove CO2 by reflux, then titrate free alkali with an ethanolic hydrochloric acid solution. Applicable mainly to sodium soaps of ordinary quality; not suitable for potassium soaps due to potassium carbonate solubility in ethanol.
Method B (Barium chloride method): precipitate soap and carbonate with barium chloride in an ethanol/water medium, then titrate the residual alkalinity (representing free KOH) with hydrochloric acid. Recommended for soft potassium soaps and mixed sodium/potassium soaps.

Reagents and concentrations

Absolute ethanol (ρ = 0.792 g/ml), ethanolic KOH ~0.1 N, ethanolic HCl ~0.1 N, phenolphthalein indicator in ethanol, and a 60% (V/V) ethanol solution for Method B.

Apparatus

Standard laboratory glassware: 500 ml flask (or conical wide-neck flask), reflux condenser, analytical balance.

Procedure highlights

Removal of CO2 by gentle reflux, careful neutralization of ethanol prior to sample dissolution (Method A), controlled precipitation with barium chloride (Method B), and endpoint detection with phenolphthalein/thymol-blue indicator mixtures.

Results and reporting

Results may be expressed as percentage NaOH (for sodium soaps) or KOH (for potassium soaps), or as milliequivalents/kg. Calculations use titrant volume (V), titrant normality (T) and test portion mass (m). Reproducibility: Method A ±0.02 (absolute), Method B ±0.05 (absolute).
Test report must state the method used, results and expression, any unusual observations, and any optional operations performed.

Applications

Quality control in soap manufacturing to quantify residual caustic alkali that affects product safety, skin irritation potential and finished-product quality.

Regulatory compliance and specification verification for sodium and potassium soap products.

Troubleshooting production issues such as incomplete neutralization or saponification.

ISO 456:1973

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications

Who should use this standard

Related standards

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