ISO 684-1974 PDF
Name in English:
St ISO 684-1974
Name in Russian:
Ст ISO 684-1974
Original standard ISO 684-1974 in PDF full version. Additional info + preview on request
Full title and description
ISO 684:1974 — Analysis of soaps — Determination of total free alkali. This International Standard specifies a volumetric titration method for determining the total free alkali content in soap samples by neutralizing free alkali with a known excess of sulphuric acid and back-titrating the excess with ethanolic potassium hydroxide.
Abstract
ISO 684:1974 gives a short, practical procedure for measuring total free alkali in soaps using ethanolic dissolution, neutralization with sulphuric acid and titration of the excess acid with ethanolic KOH. The method is simple and rapid but is not applicable where additives are decomposed by sulphuric acid or where soap colouring interferes with the phenolphthalein end-point.
General information
- Status: Published / Valid (International Standard, confirmed in subsequent reviews).
- Publication date: November 1974 (Edition 1 — 1 November 1974).
- Publisher: International Organization for Standardization (ISO).
- ICS / categories: 71.100.40 — Surface active agents.
- Edition / version: Edition 1 (1974).
- Number of pages: 2 pages (short method standard).
Scope
This standard specifies a volumetric laboratory method for determining the total free alkali in soap products. It applies to plain soaps where the prescribed reagents and phenolphthalein end-point can be used; it excludes soaps containing additives that are decomposed by sulphuric acid in the procedure and coloured soaps for which the indicator end-point is obscured.
Key topics and requirements
- Sample dissolution in an ethanolic medium to ensure the soap is in solution for titration.
- Neutralization of free alkali with a known excess of sulphuric acid.
- Back-titration of excess sulphuric acid with ethanolic potassium hydroxide using phenolphthalein as indicator.
- Calculation method to express results as total free alkali (concentration or percentage by mass).
- Limitations and applicability: not suitable for soaps with acid‑sensitive additives or interfering colours at the phenolphthalein end-point.
Typical use and users
Used by analytical and quality-control laboratories in soap and detergent manufacturers, raw-material suppliers, testing laboratories and regulatory bodies to verify free alkali levels for product quality, safety and compliance with formulation specifications.
Related standards
ISO 684:1974 replaces the earlier ISO/R 684 (1968) reference procedure and sits among other ISO and national standards for surface-active agents and soap testing (standards in the ISO/TC 91 series and national adoptions/identical standards). Users often refer to companion methods in the surface-active agents collection for related determinations.
Keywords
soap analysis; total free alkali; titration; ethanolic titration; sulphuric acid; potassium hydroxide; phenolphthalein; surface-active agents; ISO 684:1974.
FAQ
Q: What is this standard?
A: ISO 684:1974 is an International Standard that defines a laboratory titrimetric method for determining the total free alkali content in soaps.
Q: What does it cover?
A: It covers the sample preparation, reagents and the titration/back‑titration procedure (ethanolic dissolution, neutralization with sulphuric acid and back‑titration with ethanolic KOH using phenolphthalein), plus applicability limits where additives or colours interfere.
Q: Who typically uses it?
A: Quality-control and analytical laboratories in soap and detergent manufacturing, suppliers of raw materials, third‑party testing laboratories and regulators monitoring product composition and safety.
Q: Is it current or superseded?
A: ISO 684:1974 is the published edition (first edition, 1974). The standard record shows it as a published/confirmed ISO standard; users should check national catalogues or ISO for any later revisions or replacements before relying on it as the sole current method.
Q: Is it part of a series?
A: It is part of the body of ISO standards addressing surface‑active agents and related test methods produced by ISO/TC 91; it also follows on from the earlier ISO/R 684 (1968) procedure.
Q: What are the key keywords?
A: Soap analysis, total free alkali, titration, ethanolic KOH, sulphuric acid, phenolphthalein, surface-active agents.