|
Ref. No. : ISO/R 685 -1968 (E)
IS0
I N T ERN AT I O N A L ORGAN I Z AT1 O N FOR STAND AR D 1 ZATI O N
IS0 RECOMMENDATION
R 685
ANALYSIS OF SOAPS
DETERMINATION OF TOTAL ALKALI
1st EDITION
March 1968
-+.-
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore oniy
by the national standards organization of that country, being
a member of ISO.
For each individual country the oniy valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
---------------------- Page: 1 ----------------------
J
---------------------- Page: 2 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 685, Analysis of soaps - Determination of total alkali, was drawn
up by Technical Committee ISO/TC 91, Surface active agents, the Secretariat of which is held by the
Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1963 and led, in 1964, to the
adoption of a Draft IS0 Recommendation.
In December 1965, this Draft IS0 Recommendation (No. 935) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by
the following Member Bodies :
Australia Israel Switzerland
Austria Japan Turkey
Belgium Netherlands U.A.R.
Brazil New Zealand United Kingdom
Canada
Poland Yugoslavia
Chile Portugal
France Romania
Germany South Africa,
Hungary Rep. of
Spain
Ireland
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in March 1968, to accept it as an IS0 RECOMMENDATION.
-3-
---------------------- Page: 3 ----------------------
ISO/R 685 -1968 (E
IS0 Recommendation R 685 March 1968
ANALYSIS OF SOAPS
DETERMINATION OF TOTAL ALKALI
1. SCOPE
This IS0 Recommendation describes the method for the determination of the total alkali in soaps,
excluding compounded products. *
1.1 Field of application
This method allows the simultaneous determination of the total alkali and the total crude fatty
acids.** It is not applicable to coloured soaps, if the colour interferes with the methyl orange
end point.***
2. DENNITION
By total alkali is understood the sum of the alkali bases combined as soap with fatty and rosin acids,
as well as those corresponding to the free caustic or carbonated alkali and to the silicates present (if
any) which can be titrated under the test conditions.
The results are expressed as a percentage of sodium hydroxide (NaOH) or of potassium hydroxide
(KOH), according to whether sodium or potassium soaps are concerned.
3. PRiNCIPLE
Decomposition of the soap by a known amount of acid and titration of the excess of acid.
4. REAGENTS
4.1 Sulphuric acid or hydrochloric acid, standard volumetric solution, approximately N.
4.2 Sodium hydroxide, standard aqueous volumetric solution, approximately N, standardized with
methyl orange.
4.3 Beeswax, paraffin wax or stearic acid, very light in colour (or a mixture of these) designated as
“wax” in the text, free from impurities and previously dried by heating to about 120 OC.
Methyl orange solution, 0.2 per 100 ml in distilled water.
4.4
See also IS0 Recommendation R 684, Analysis of soaps - Determination of total pee alkali.
**
The procedure specifies dissolving
...