EN ISO 9963-2:1995

SLOVENSKI STANDARD
01-januar-1998
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Water quality - Determination of alkalinity - Part 2: Determination of carbonate alkalinity
(ISO 9963-2:1994)
Wasserbeschaffenheit - Bestimmung der Alkalinität - Teil 2: Bestimmung der
Carbonatalkalinität (ISO 9963-2:19954)
Qualité de l'eau - Détermination de l'alcalinité - Partie 2: Détermination de l'alcalinité
carbonate (ISO 9663-2:1994)
Ta slovenski standard je istoveten z: EN ISO 9963-2:1995
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
IS0
STANDARD
First edition
1994-l I-1 5
Water quality - Determination of
alkalinity -
Part 2:
Determination of carbonate alkalinity
Qua/it6 de I’eau - 06 termination de I’alcalinit6 -
Partie 2: D6 termha tion de I ‘alcalinit6 carbonate
Reference number
IS0 99632:1994(E)
IS0 9963-2: 1994(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each 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, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 9963-2 was prepared by Technical Committee
lSO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical,
biochemical methods.
IS0 9963 consists of the following parts, under the general title Water
quality - Determination of alkalinity:
- Part 1: Determination of total and composite alkalinity
- Part 2: Determination of carbonate alkalinity
Annexes A and B of this part of IS0 9963 are for information only.
0 IS0 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without 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 0 IS0 IS0 9963-2: 1994(E)
Water quality - Determination of alkalinity -
Part 2:
Determination of carbonate alkalinity
IS0 385-l :1984, Laboratory glassware - Burettes -
1 Scope
Part 1: General requirements.
This part of IS0 9963 specifies a method for the
IS0 3696: 1987, Water for analytical laboratory use -
titrimetric determination of carbonate alkalinity in
Specification and test methods.
natural and drinking water. Using a higher pH value for
than the method specified in
the endpoint
IS0 5667-2:1991, Water quality - Sampling -
IS0 9963-1, the influence of other hydrogen ac-
Part 2: Guidance on sampling techniques.
ceptors, such as anions of humic acids, is reduced by
the procedure.
IS0 6107-2:1989, Water quality - Vocabulary -
Part 2.
The method is intended for samples with a carbonate
alkalinity between 0,Ol mmol/l and 4 mmol/l (as H+
IS0 9963-l :l994, Water quality - Determination of
equivalents). For samples containing higher concen-
alkalinity - Part 1: Determination of total and com-
trations of alkalinity, a smaller test portion can be used
posite alkalinity.
for analysis.
IEC 746-2:1982, Expression of performance of
In this context, carbonate alkalinity is often called total
electrochemical analyzers - Part 2: pH value.
alkalinity and usually has nearly the same numerical
value as methyl orange alkalinity (MO-alkalinity).
The endpoint detection, using a pH-meter is less
3 Definition
prone to interferences than the use of the indicator.
For the purposes of this part of IS0 9963, the follow-
ing definition applies.
3.1 alkalinity (A): The quantitative capacity of
2 Normative references
aqueous media to react with hydrogen ions.
[ISO 6107-21
The following standards contain provisions which,
through reference in this text, constitute provisions
In this method, the endpoint is chosen in such a way
of this part of IS0 9963. At the time of publication, the
as to permit the full neutralization of the carbonate
editions indicated were valid. All standards are subject
system.
to revision, and parties to agreements based on this
part of IS0 9963 are encouraged to investigate the
A = c(HC0,) + 2c(CO;-) + c(OH-) + c(X) - c(H+)
possibility of applying the most recent editions of the
standards indicated below. Members of IEC and IS0 Usually proton acceptors (X) other than the carbonate
maintain registers of currently valid International system are present in low concentrations and can of-
Standards. ten be disregarded. Examples of such buffering sub-
0 IS0
IS0 9963-2: 1994(E)
stances are ammonia, phosphate, and anions of
5 Reagents
humic and other organic acids.
Use only reagents of recognized analytical grade.
Commercially available, ready-made solutions may be
used.
4 Principle
5.1 Water, grade 2 in accordance with IS0 3696,
Alkalinity is determined by titration with hydrochloric
free of interfering concentrations of acid or alkali and
acid, with simultaneous removal of carbon dioxide. In
with a conductivity of less than 0,l mS/m.
this way, a precise endpoint independent of the initial
concentration of alkalinity can be used. The endpoint
preferably needs to be as close to neutrality as poss- 5.2 Gas, free from carbon dioxide, nitrogen or al-
ternatively a gas free from carbon dioxide obtained by
ible but still low enough to allow the removal of car-
passing air through a standing tube filled with soda
bon dioxide produced. In this part of IS0 9963, the
lime or another compound that absorbs carbon diox-
endpoint is set at pH 5,4, since the pH value can
easily be determined with the indicator chosen. The ide. Then pass the gas through a wash bottle con-
induced systematic error is corrected by titrating a taining water and subsequently the gas distribution
blank. tube (see figure 1).
Volume about 75 ml
Glass wool
Poros
Soda lime
or equivalent
Air
Filter funnel
c
Figure 1 - Principle for absorption of carbon dioxide from air

0 IS0 IS0 9963-2: 1994(E)
where
5.3 Mixed indicator pH 5,4.
c(HCI) is the concentration, expressed in
Dissolve 0,040 g + 0,005 g of methyl red and
moles per litre, of the hydrochloric
0,060 g + 0,005 g if bromocresol green in 100 ml of
acid solution (5.5);
ethanol r> 90 % (WV)]. Neutralize the solution with
about 2 ml of 0,l mol/l sodium hydroxide until a
m is the mass, in grams, of sodium
brown colour appears. Check the neutrality of the in-
carbonate taken for the preparation
dicator solution by titration to endpoint of one sample.
of solution 5.4;
If the brown colour does not remain after the addition
of 10 more drops of the indicator, adjust the pH of the
is the volume, in millilitres, of sodium
indicator solution. Stored in an amber glas
...