SIST EN ISO 20483:2007
(Main)Cereals and pulses - Determination of the nitrogen content and calculation of the crude protein content - Kjeldahl method (ISO 20483:2006)
Cereals and pulses - Determination of the nitrogen content and calculation of the crude protein content - Kjeldahl method (ISO 20483:2006)
This International Standard specifies a method for the determination of the nitrogen content of cereals, pulses and derived products, according to the Kjeldahl method, and a method for calculating the crude protein content. The method does not distinguish between protein nitrogen and non-protein nitrogen. If it is important to determine the non-protein nitrogen content, an appropriate method can be applied.
Getreide und Hülsenfrüchte - Bestimmung des Stickstoffgehaltes und Berechnung des Rohproteingehaltes - Kjeldahl-Verfahren (ISO 20483:2006)
Diese Internationale Norm legt ein Verfahren zur Bestimmung des Stickstoffgehalts von Getreide, Hülsen¬früchten und deren Produkten nach dem Kjeldahl-Verfahren und ein Verfahren zur Berechnung des Rohproteingehalts fest.
Das Verfahren unterscheidet nicht zwischen Proteinstickstoff und Nichtproteinstickstoff. Wenn es wichtig ist, den Gehalt an Nichtproteinstickstoff zu bestimmen, kann ein geeignetes Verfahren angewendet werden.
ANMERKUNG In bestimmten Fällen ist eine vollständige Erfassung des in Nitraten und Nitriten vorliegenden Stickstoffs mit diesem Verfahren nicht möglich.
Céréales et légumineuses - Détermination de la teneur en azote et calcul de la teneur en protéines brutes - Méthode de Kjeldahl (ISO 20483:2006)
L'ISO 20483:2006 spécifie une méthode pour la détermination de la teneur en azote des céréales, des légumineuses et des produits dérivés, selon la méthode de Kjeldahl, ainsi qu'une méthode de calcul de la teneur en protéines brutes.
La méthode ne fait pas la distinction entre l'azote protéique et l'azote non protéique. S'il importe de déterminer la teneur en azote non protéique, on peut appliquer une méthode appropriée.
Žito in stročnice - Določevanje dušika in izračun vsebnosti surovih beljakovin - Metoda po Kjeldahlu (ISO 20483:2006)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 20483:2007
01-marec-2007
äLWRLQVWURþQLFH'RORþHYDQMHGXãLNDLQL]UDþXQYVHEQRVWLVXURYLKEHOMDNRYLQ
0HWRGDSR.MHOGDKOX ,62
Cereals and pulses - Determination of the nitrogen content and calculation of the crude
protein content - Kjeldahl method (ISO 20483:2006)
Getreide und Hülsenfrüchte - Bestimmung des Stickstoffgehaltes und Berechnung des
Rohproteingehaltes - Kjeldahl-Verfahren (ISO 20483:2006)
Céréales et légumineuses - Détermination de la teneur en azote et calcul de la teneur en
protéines brutes - Méthode de Kjeldahl (ISO 20483:2006)
Ta slovenski standard je istoveten z: EN ISO 20483:2006
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
SIST EN ISO 20483:2007 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN ISO 20483
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2006
ICS 67.060
English Version
Cereals and pulses - Determination of the nitrogen content and
calculation of the crude protein content - Kjeldahl method (ISO
20483:2006)
Céréales et légumineuses - Détermination de la teneur en Getreide und Hülsenfrüchte - Bestimmung des
azote et calcul de la teneur en protéines brutes - Méthode Stickstoffgehalts und Berechnung des Rohproteingehalts -
de Kjeldahl (ISO 20483:2006) Kjeldahl-Verfahren (ISO 20483:2006)
This European Standard was approved by CEN on 28 October 2006.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20483:2006: E
worldwide for CEN national Members.
---------------------- Page: 2 ----------------------
EN ISO 20483:2006 (E)
Foreword
This document (EN ISO 20483:2006) has been prepared by Technical Committee ISO/TC 34
"Agricultural food products" in collaboration with Technical Committee CEN/TC 338 "Cereal and
cereal products", the secretariat of which is held by AFNOR.
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 May 2007, and conflicting national standards
shall be withdrawn at the latest by May 2007.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 20483:2006 has been approved by CEN as EN ISO 20483:2006 without any
modifications.
2
---------------------- Page: 3 ----------------------
INTERNATIONAL ISO
STANDARD 20483
First edition
2006-11-01
Cereals and pulses — Determination of
the nitrogen content and calculation of
the crude protein content — Kjeldahl
method
Céréales et légumineuses — Détermination de la teneur en azote et
calcul de la teneur en protéines brutes — Méthode de Kjeldahl
Reference number
ISO 20483:2006(E)
©
ISO 2006
---------------------- Page: 4 ----------------------
ISO 20483:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
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 at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
---------------------- Page: 5 ----------------------
ISO 20483:2006(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle. 2
5 Reagents. 2
6 Apparatus . 3
7 Sampling. 3
8 Preparation of test sample. 3
9 Determination of the moisture content. 4
10 Procedure . 4
10.1 General. 4
10.2 Test portion . 4
10.3 Determination. 4
10.4 Blank test. 5
10.5 Test with reference material (Check test) . 5
11 Expression of results . 5
11.1 Nitrogen content . 5
11.2 Crude protein content . 6
12 Precision. 6
12.1 Interlaboratory test . 6
12.2 Repeatability. 6
12.3 Reproducibility. 6
12.4 Critical difference. 7
13 Test report . 7
Annex A (informative) Results of interlaboratory tests. 8
Annex B (informative) Critical difference and practical application of the repeatability and
reproducibility limits to different protein contents . 10
Annex C (informative) Factors for converting nitrogen content to protein content. 12
Bibliography . 13
© ISO 2006 – All rights reserved iii
---------------------- Page: 6 ----------------------
ISO 20483:2006(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 20483 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals
and pulses.
iv © ISO 2006 – All rights reserved
---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO 20483:2006(E)
Cereals and pulses — Determination of the nitrogen content
and calculation of the crude protein content — Kjeldahl method
WARNING — The use of this standard may involve hazardous materials, operations and equipment.
This standard does not purport to address all the safety problems associated with its use. It is the
responsibility of the user of this standard to establish appropriate safety practices and determine the
applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies a method for the determination of the nitrogen content of cereals, pulses
and derived products, according to the Kjeldahl method, and a method for calculating the crude protein
content.
The method does not distinguish between protein nitrogen and non-protein nitrogen. If it is important to
determine the non-protein nitrogen content, an appropriate method can be applied.
NOTE In certain cases, full recovery of the nitrogen in nitrates and nitrites is not possible by this method.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 712, Cereals and cereal products — Determination of moisture content — Routine reference method
ISO 6540, Maize — Determination of moisture content (on milled grains and on whole grains)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
nitrogen content
quantity of nitrogen determined after application of the procedure described in this International Standard
NOTE It is expressed as mass fraction of dry product, in percent.
3.2
crude protein content
quantity of crude protein obtained from the nitrogen content as determined by applying the method described
in this document, calculated by multiplying this content by an appropriate factor depending on the type of
cereal or pulse
NOTE It is expressed as mass fraction of dry product, in percent.
© ISO 2006 – All rights reserved 1
---------------------- Page: 8 ----------------------
ISO 20483:2006(E)
4 Principle
A test portion is digested by sulfuric acid in the presence of a catalyst. The reaction products are made
alkaline then distilled. The liberated ammonia is collected in a boric acid solution, which is titrated with a
sulfuric acid solution, to determine the nitrogen content and calculate the crude protein content.
5 Reagents
Use only nitrogen-free reagents of recognized analytical grade, except for the reference materials, and
distilled or demineralized water or water of equivalent purity.
WARNING — The reagents described in 5.4, 5.8, 5.11 and 5.12 shall be handled with precautions.
5.1 Potassium sulfate (K SO ).
2 4
5.2 Copper(II) sulfate pentahydrate (CuSO ·5H O).
4 2
5.3 Titanium oxide (TiO ).
2
5.4 Sulfuric acid, c(H SO ) = 18 mol/l, ρ (H SO ) = 1,84 g/ml.
2 4 20 2 4
5.5 Paraffin oil.
5.6 Acetanilide (C H NO), having a melting point of 114 °C and nitrogen content of 10,36 g/100 g.
8 9
5.7 Tryptophan (C H N O ), having a melting point of 282 °C and nitrogen content of 13,72 g/100 g.
11 12 2 2
5.8 Phosphorus pentoxide (P O ).
2 5
5.9 Boric acid, aqueous solution, ρ (H BO ) = 40 g/l, or any other concentration recommended for the
20 3 3
apparatus being used.
5.10 Coloured indicator
Add volumes of Solution A (5.10.1) and Solution B (5.10.2) as recommended for the apparatus being used (for
example: 5 volumes of Solution A and 1 volume of Solution B).
NOTE 1 It is possible to use a ready-to-use solution of boric acid containing the coloured indicator (5.9 + 5.10).
NOTE 2 The ratio of Solutions A and B may be adjusted depending on the apparatus.
The titration may also be carried out potentiometrically by the use of pH-electrode, which has to be checked
every day.
5.10.1 Solution A
Bromocresol green (C H Br O S): 200 mg.
21 14 4 5
Ethanol (C H OH), with a volume fraction of 95 %: quantity sufficient for 100 ml solution.
2 5
5.10.2 Solution B
Methyl red (C H N O ): 200 mg.
15 15 3 2
Ethanol (C H OH), with a volume fraction of 95 %: quantity sufficient for 100 ml solution.
2 5
2 © ISO 2006 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 20483:2006(E)
5.11 Sodium hydroxide, aqueous solution (NaOH), with a mass fraction of 33 %, or a mass fraction of 40 %,
with nitrogen content less than or equal to 0,001 %.
Sodium hydroxide of technical grade may also be used when its nitrogen content is less than or equal to
0,001 %.
5.12 Sulfuric acid, standard volumetric solution, c(H SO ) = 0,05 mol/l.
2 4
The use of H SO instead of HCl is recommended because H SO does not have the tendency to produce
2 4 2 4
bubbles in the connecting tubes.
5.13 Ammonium sulfate, standard volumetric solution, c(NH ) SO = 0,05 mol/l.
4 2 4
Alternatively, a salt such as (NH ) Fe(SO ) ·6H O may be used.
4 2 4 2 2
5.14 Pumice stone, granulated, washed in hydrochloric acid and ignited.
5.15 Sucrose (optional), free from nitrogen.
6 Apparatus
6.1 Mechanical grinder.
6.2 Sieve, with aperture size 0,8 mm.
6.3 Analytical balance, capable of weighing to the nearest 0,001 g.
6.4 Digestion, distillation and titration apparatus.
The homogeneous temperature distribution of the digestion unit should be ascertained.
The assessment of temperature homogenei
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.