EN ISO 12779:2013

SLOVENSKI STANDARD
01-september-2013
/DNWR]D'RORþHYDQMHYRGH0HWRGDSR.DUOX)LVFKHUMX,62
Lactose - Determination of water content - Karl Fischer method (ISO 12779:2011)
Lactose - Bestimmung des Wassergehaltes - Karl-Fischer-Verfahren (ISO 12779:2011)
Lactose - Détermination de la teneur en eau - Méthode de Karl Fischer (ISO
12779:2011)
Ta slovenski standard je istoveten z: EN ISO 12779:2013
ICS:
67.100.01 0OHNRLQPOHþQLSURL]YRGLQD Milk and milk products in
VSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 12779
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2013
ICS 67.100.99
English Version
Lactose - Determination of water content - Karl Fischer method
(ISO 12779:2011)
Lactose - Détermination de la teneur en eau - Méthode de Lactose - Bestimmung des Wassergehaltes - Karl-Fischer-
Karl Fischer (ISO 12779:2011) Verfahren (ISO 12779:2011)
This European Standard was approved by CEN on 16 May 2013.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12779:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
The text of ISO 12779:2011 has been prepared by Technical Committee ISO/TC 34 “Food products” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 12779:2013 by
Technical Committee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis” the secretariat
of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2013, and conflicting national standards shall be withdrawn
at the latest by November 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 12779:2011 has been approved by CEN as EN ISO 12779:2013 without any modification.

INTERNATIONAL ISO
STANDARD 12779
IDF
First edition
2011-11-01
Lactose — Determination of water
content — Karl Fischer method
Lactose — Détermination de la teneur en eau — Méthode de Karl
Fischer
Reference numbers
ISO 12779:2011(E)
IDF 227:2011(E)
©
ISO and IDF 2011
ISO 12779:2011(E)
IDF 227:2011(E)
©  ISO and IDF 2011
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 either ISO or IDF at the respective
address below.
ISO copyright office International Dairy Federation
Case postale 56  CH-1211 Geneva 20 Silver Building  Boulevard Auguste Reyers 70/B  B-1030 Brussels
Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88
Fax + 41 22 749 09 47 Fax + 32 2 733 04 13
E-mail copyright@iso.org E-mail info@fil-idf.org
Web www.iso.org Web www.fil-idf.org
Published in Switzerland
ii © ISO and IDF 2011 – All rights reserved

ISO 12779:2011(E)
IDF 227:2011(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 normally carried out through
ISO 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. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12779IDF 227 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and
IDF.
ISO 12779:2011(E)
IDF 227:2011(E)
Foreword
IDF (the International Dairy Federation) is a non-profit organization representing the dairy sector worldwide.
IDF membership comprises National Committees in every member country as well as regional dairy
associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right to
be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in
the development of standard methods of analysis and sampling for milk and milk products.
The main task of Standing Committees is to prepare International Standards. Draft International Standards
adopted by the Standing Committees are circulated to the National Committees for endorsement prior to
publication as an International Standard. Publication as an International Standard requires approval by at least
50 % of IDF National Committees casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. IDF shall not be held responsible for identifying any or all such patent rights.
ISO 12779IDF 227 was prepared by the International Dairy Federation (IDF) and Technical Committee
ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF
and ISO.
All work was carried out by Joint ISO-IDF Project Group (C09), Determination of water content in lactose by
Karl Fischer method of the Standing Committee on Analytical Methods for Composition (SCAMC) under the
aegis of its project leader, Prof. Dr. H.-D. Isengard (DE).

iv © ISO and IDF 2011 – All rights reserved

ISO 12779:2011(E)
INTERNATIONAL STANDARD
IDF 227:2011(E)
Lactose — Determination of water content — Karl Fischer
method
1 Scope
This International Standard specifies a method for the determination of the water content of lactose by
Karl Fischer (KF) titration.
2 Principle
The test sample is directly titrated with a commercially available two-component Karl Fischer reagent. The
water content is calculated from the amount of reagent used.
Titration at a temperature of approximately 40 °C gives shorter titration times and sharper end points. Only at
this or higher temperatures is the use of a one-component Karl Fischer reagent (3.1) recommended.
3 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and only distilled or
demineralized water or water of equivalent purity. Avoid absorption of moisture from the environment.
1)
3.1 Karl Fischer (KF) reagent . The KF reagent is a commercially available pyridine-free two-component
reagent consisting of a titration component (3.2) and a solvent component (3.3). The titration component (3.2)
is a methanolic solution of iodine and the solvent component (3.3) is a methanolic solution of sulfur dioxide
and an appropriate base (e.g. imidazole).
Alternatively, a pyridine-free one-component KF reagent can also be used which only consists of a titration
component. The titration component (3.2) is a solution of iodine, sulfur dioxide and an appropriate base (e.g.
imidazole) in a suitable solvent (e.g. diethylene glycol monoethyl ether). The solvent component (3.3) is
methanol (3.5). This combination of a one-component titration reagent and methanol is only recommended if
the titration is carried out at a temperature of approximately 40 °C or higher.
3.2 Titration component. The titration component of the KF reagent (3.1) shall have a water equivalent of
approximately 2 mg/ml of water.
A KF reagent with a water equivalent of approximately 5 mg/ml of water is also possible if a KF apparatus with
a burette of capacity 5 ml is used (4.1).
3.3 Solvent component. The solvent component of the KF reagent as specified in 3.1.
3.4 Water standard, w(H O) = 10 mg/g.
® ® ® ®
1) Hydranal -Titrant 2/Hydranal -Solvent from Sigma-Aldrich and apura Titrant 2/apura Solvent from Merck are
® ®
examples of commercially available two-component systems. Hydranal -Composite 2 from Sigma-Aldrich and apura
CombiTitrant 2 from Merck are examples of commercially available one-component reagents. This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO and IDF of these products.
ISO 12779:2011(E)
IDF 227:2011(E)
For the determination of the water equivalent of the titration component, use a commercially available liquid
water standard containing 10 mg/g of water.
3.5 Methanol (CH OH), with a mass fraction of water of not more than 0,05 %.
4 Apparatus
Usual laboratory apparatus and, in particular, the following. Equipment shall be completely dry when used.
4.1 Karl Fischer (KF) apparatus. Use an automatic volumetric KF apparatus, preferably with a burette of
capacity 10 ml.
The burette should be of capacity 5 ml if a KF reagent with a water equivalent of approximately 5 mg/ml of
water is used (see 3.2).
For quicker titrations at approximately 40 °C, use a double-jacketed titration vessel with a water inlet and
outlet to carry out the titration.
4.2 Water bath, capable of maintaining a water temperature of 40 °C  5 °C under thermostatic control,
with a pump for heating the double-jacketed titration vessel of the KF apparatus (4.1).
NOTE The use of a water bath with thermostatic control is only necessary if the titrations are carried out at
temperatures above room temperature.
4.3 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg.
4.4 Disposable syringes, of capacity 5 ml or 10 ml, for quantifying the water standard (3.4).
4.5 Glass weighing spoon, for dosing the test sample.
5 Sampling
A representative sample should have been sent to the laboratory. It should not have been damaged or
changed during transport or storage.
Sampling is not part of the method specified in this International Standard. A recommended sampling method
[1]
is given in ISO 707  IDF 50 .
6 Procedure
6.1 KF apparatus drift
6.1.1 Determine the drift of the KF apparatus (4.1) every day and/or when the working conditions change as
follows.
Add to the titration vessel of the KF apparatus (4.1) approximately 30 ml of solvent component (3.3).
Pre-titrate the solvent component. Then carry out a titration over 5 min (without addition of a test sample).
If determinations (6.5) are carried out at 40 °C, heat the vessel and its contents using the water bath (4.2) to
40 °C before pre-titrating the solvent component and carrying out the titration without addition of a test sample.
IMPORTANT — During each titration, the amount of solvent component used shall completely cover
the electrodes of the KF apparatus.
2 © ISO and IDF 2011 – All rights reserved

ISO 12779:2011(E)
IDF 227:2011(E)
6.1.2 Calculate the KF apparatus drift, q , in millilitres per minute, by using Equation (1):
V
V
d
q  (1)
V
t
where
V is the volume, in millilitres, of the titration component (3.2) in the titration (6.1.1);
d
t is the numerical val
...