INTERNATIONAL ISO
STANDARD 4325
Second edition
1990-04-15
Soaps and detergents - Determination of
chelating agent content - Titrimetric method
iTeh STANDARD
Savons et detergents PREVIEW
- DHermination de Ia teneur en agent
s&questran t - Methode titrimetrique
(standards.iteh.ai)
ISO 4325:1990
https://standards.iteh.ai/catalog/standards/sist/8a12439a-d662-457e-b79f-
15fd7615b233/iso-4325-1990
Reference number
ISO 4325: 199O(E)
ISO 4325:1990(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide
federation of national Standards bodies (ISO member bodies). The work
of preparing international Standards is normaliy carried out through ISO
technical committees. Esch member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardizatlon.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Interna-
tional Standard requires approval by at least 75 % of the member bodies
casting a vote. iTeh STANDARD PREVIEW
ISO/TC 91, Surface active agents.
(standards.iteh.ai)
International Standard ISO 4325 was prepared by Technical Committee
This second edition cancels and replaces the ISO first 4325:1990
edition (ISO
https://standards.iteh.ai/catalog/standards/sist/8a12439a-d662-457e-b79f-
4325:1977), of which it constitutes a minor technical revision.
15fd7615b233/iso-4325-1990
0 ISO 1990
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronie or mechanical, including photocopylng and mlcrofilm, wlthout
Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
INTERNATIONAL STANDARD ISO 4325:1990(E)
Soaps and detergents - Determination of chelating agent
content - Titrimetric method
1 Scope 4 Reagents
This International Standard specifies a method of During the analysis, use only reagents of recognized
analysis for the determination of the chelating agent analytical grade and water of purity grade 3 as de-
content of detergent compositions and soaps con- fined in ISO 3696.
taining not more than 2 % (m/m) of chelating agent.
Ethylenediaminetetraacetic acid (EDTA) is one of the 4.1 Hydrochlorit acid solution, c(HCI) = 5 mol/l.
most widely used chelating agents and the method
iTeh STANDARD PREVIEW
has been designed principally for determining this
compound and its salts. Before determining other 4.2 Acetate buffer solution, pH = 4,65.
chelating agents,
diaminetetraacetic
or (standards.iteh.ai)
determining ethylene-
acid in the presence of other Mix equal volumes of acetic acid solution,
chelating agents, the applicability of the method c(CH,COOH) = 0,4 mol/l, and sodium hydroxide
should be confirmed. ISO 4325:1990
Solution, c(NaOH) = 0,2 mol/l.
https://standards.iteh.ai/catalog/standards/sist/8a12439a-d662-457e-b79f-
15fd7615b233/iso-4325-1990
2 Normative references
4.3 PAN lndlcator, 0,l % (I@I) Solution of
The following Standards contain provisions which, 1-(2-pyrldylazo)-2-naphthol in ethanol.
through reference in this text, constitute provisions DO not keep this Solution longer than 7 days.
of this International Standard. At the time of publi-
cation, the editions indicated were valid. All stand-
ards are subject to revision, and Parties to
agreements based on this International Standard 4.4 Copper(ll) sulfate, Standard volumetric Solution,
are encouraged to investigate the possibility of ap- c(CuSOJ = 0,OlOO mol/l.
plying the most recent editions of the Standards in- Weigh out, to the nearest 1 mg, 2,497 g of copper(ll)
dicated below. Members of IEC and ISO maintain sulfate pentahydrate (CuS0,.5H,O), of minimum pu-
registers of currently valid International Standards. rity 99,5 % (m/m) and dissolve in water.
Quantitatively transfer the Solution obtained to a
ISO 385-1:1984, Laboratory glassware - Burettes - 1000 ml one-mark volumetric flask, dilute to the
Part 1: General requirements. mark and mix.
ISO 607:1980, Surface active agents and detergents
- Methods of Sample division.
5 Apparatus
ISO 3696:1987, Water for analytical laboratory use -
Specification and test methods. Ordinary laboratory apparatus and
3 Principle
5.1 pH-meter, with electrodes and stirrer.
A test portion of the Sample is dissolved in water,
the pH of the Solution adjusted to 4,65 and the sol-
ution titrated against Standard copper(ll) sulfate sol- 5.2 Burette, capacity 50 ml, complying with the re-
ution using 1-(2-pyridylazo)-2-naphthol as indicator. quirements of class A of ISO 385-1.
ISO 4325:199O(E)
6 Sampling V is the volume, in millilitres, of the
copper(ll) sulfate solution (4.4) used for
The Iaboratory Sample of soap or detergent shall be the titration;
prepared and stored in accordance with the in-
C is the actual concentration, expressed in
structions given in ISO 607.
moles of CuSO, per litre, of the copper(ll)
sulfate Solution used;
7 Procedure
m is the mass, in grams, of the test portion
.
7.1 Test Portion (7 .1) 9
292 is the relative molecular mass of
Weigh, to the nearest 0,l g, 10 g of the Iaboratory ethylenediaminetetraacetic acid.
Sample into a beaker or conical flask.
8.2 Preclslon
7.2 Determination
8.2.1 Repeatability
Add 100 ml of water to the test portion, warm and
stir to dissolve. Introduce the electrodes, connected The maximum differente found between the results
to the previously calibrated pH-meter (5.1), and add of two determinations carried out on the Same sam-
hydrochloric acid solution (4.1) until the pH is ple in rapid succession by the Same analyst using
4,6 -+ 0,5. Raise, rinse and remove the electrodes. the Same apparatus should not be more than
0,Ol % (m/m) for EDTA contents up to 2 % (m/m).
NOTE 1 In most cases, there is no interference by other
components of the product, for example fatty acids, but id
necessary the fatty acids of soaps may be removed by 8.2.2 Repraducibility
filtration through a wet filter Paper.
Add 5 ml of
iTeh STANDARD
the acetate buffer Solution (4.2) and
PREVIEW between two results ob-
The maximum differente
tained on the Same Sample, in two different labora-
0,4 ml of the
about 60 “C
(standards.iteh.ai)
PAN indicator Solution (4.3). Heat to
and titrate with the copper(ll) sulfate
tories, should not differ by more than 0,06 % (m/m)
for liquid soaps, for EDTA contents up to
Solution (4.4) until the indicator changes from yellow 2 % (m/m), and by 0,04 % (m/m) for detergents, for
to wine-red. ISO 4325:1990
EDTA contents up to 2 % (m/m).
https://standards.iteh.ai/catalog/standards/sist/8a12439a-d662-457e-b79f-
NOTE 2 The wine-red colour should persist for 15fd7615b233/iso-4325-1990
at least
1 min. A fading end-point suggests that some other
9 Test report
chelating agent is present.
The test report shall include the following informa-
tion:
8 Expression of results
a) all information necessary for the complete iden-
8.1 Calculation tifrcation of the Sample;
The chelating agent content, expressed as a per- W the method used (i.e. a reference to this Interna-
centage by mass of ethylenediaminetetraacetic acid tional Standard);
(EDTA), is given by the following formula:
vc 100 Cl the results and the way in which they have been
3 x 292 x yj-- expressed;
IO
where
d) any operational details which are not specified
in this International Standard or in the Interna-
tional Standards to which reference is made, or
which are regarded as optional, as well as any
incidents liable to have affected the results.
UDC 661 .185/.187:543.24
Descriptors: surfactants, detergents, soaps, Chemical analysis, determination of content, EDTA, volumetric analysis.
Price based on 2 pages
