CEN/TR 16875:2015
(Main)Cereal and cereal products - Technical report of the interlaboratory study for the determination of impurities content in maize (Zea mays, L.) and sorghum (Sorghum bicolor, L.)
Cereal and cereal products - Technical report of the interlaboratory study for the determination of impurities content in maize (Zea mays, L.) and sorghum (Sorghum bicolor, L.)
The term impurities applies to all components of a grain sample that differ from the normal basic cereal. It includes the following groups: broken grains, other cereals, grains damaged by pests, grains overheated during drying, sprouted grains, extraneous seeds, unsound grains, extraneous matter and impurities of animal origin.
The principle of the determination of impurities content is to separate all the groups of impurities from the normal basic cereal grains of unimpaired quality by sieving and manual selection out of a subsample and to quantify them. There are various problems in the determination of impurities:
Firstly, the identification of the different groups of impurities depends strongly on the experience and the knowledge of the investigator.
Also experienced investigators can differ in their characterization of grains.
Finally, one is faced with the fact that grain, even after mixing, is rarely homogenous. In other words, if a sample was divided by a sample divider into a number of portions, the amount of a specific group of impurities in each portion could be different, even if absolutely no human or machine error occurred in each determination.
These problems will result in variation of the results of the determination.
An international interlaboratory test for the determination of impurities, according to this standard and involving 14 laboratories in 4 countries, was carried out with 5 maize and 3 sorghum samples. It was asked to participants to make determination in duplicate.
Ten laboratories reported results for the complete sample set and two only for corns.
The test materials ranged between:
- 0,0 % and 2,7 % for broken grains;
- 0,2 % and 3,5 % for grain impurities;
- 0,0 % and 0,1 % for sprouted grains;
- 0,5 % and 3,3 % for miscellaneous impurities;
- 1,8 % and 8,7 % for total impurities.
The aim of the study is to determine the precision, repeatability and reproducibility of the method of determination of impurities content in maize and sorghum samples.
The analyses were realized in March - April 2011.
It occurs according to the ISO 5725:1994.
Céréales et produits céréaliers - Rapport technique de l'étude interlaboratoires pour la détermination de la teneur en impuretés dans le maïs (Zea mays, L.) et le sorgho (Sorghum bicolor, L.)
Žito in žitni proizvodi - Tehnično poročilo medlaboratorijske študije o določevanju nečistoč v koruzi (Zea mays, L.) in prosu (Sorghum bicolor, L.)
Izraz »nečistoče« se nanaša na vse sestavine vzorca zrnja, ki se razlikujejo od običajnega osnovnega žita. Vključuje naslednje skupine: lomljena zrna, druga žita, zrna, ki so jih poškodovali škodljivci, zrna, ki so se pregrela med sušenjem, nakaljena zrna, tuja semena, nezdrava zrna, tuje snovi in nečistoče živalskega izvora.
Načelo določevanja nečistoč je ločiti vse skupine nečistoč od običajnega osnovnega žita v zrnju neoslabljene kakovosti s sejanjem in ročnim prebiranjem podvzorca ter jih količinsko opredeliti. Pri določevanju nečistoč se pojavljajo različne težave.
Opredelitev različnih skupin nečistoč je na primer zelo odvisna od izkušenj in znanja preiskovalca.
Tudi izkušeni preiskovalci lahko različno določijo lastnosti zrn.
Nenazadnje je treba upoštevati dejstvo, da je zrnje tudi po mešanju redko homogeno. Drugače povedano, če bi se vzorec z razdeljevalnikom vzorca razdelil na več delov, bi se lahko količina določene skupine nečistoč med posameznimi deli razlikovala, čeprav pri posamezni določitvi zagotovo ni bilo človeške ali strojne napake.
Zaradi teh težav bodo rezultati določevanja različni.
Mednarodni medlaboratorijski preskus za določevanje nečistoč, ki je bil izveden v skladu s tem standardom in pri katerem je sodelovalo 14 laboratorijev v 4 državah, je bil izveden s 5 vzorci koruze in 3 vzorci prosa. Sodelujoči laboratoriji so morali vsako določevanje izvesti po dvakrat.
Deset laboratorijev je sporočilo rezultate za celoten sklop vzorcev, dva pa le za koruzo.
Preskusne snovi so zajemale:
– 0,0 % do 2,7 % za lomljena zrna;
– 0,2 % do 3,5 % za nečistoče zrn;
– 0,0 % do 0,1 % za nakaljena zrna;
– 0,5 % do 3,3 % za druge nečistoče;
– 1,8 % do 8,7 % za celotne nečistoče.
Cilj študije je določiti natančnost, ponovljivost in možnost reprodukcije metode za določevanje nečistoč v vzorcih koruze in prosa.
Analize so se izvajale od marca do aprila 2011.
Upoštevan je bil standard ISO 5725:1994.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2015
äLWRLQåLWQLSURL]YRGL7HKQLþQRSRURþLORPHGODERUDWRULMVNHãWXGLMHRGRORþHYDQMX
QHþLVWRþYNRUX]L =HDPD\V/ LQSURVX 6RUJKXPELFRORU/
Cereal and cereal products - Technical report of the interlaboratory study for the
determination of impurities content in maize (Zea mays, L.) and sorghum (Sorghum
bicolor, L.)
Céréales et produits céréaliers - Rapport technique de l'étude interlaboratoires pour la
détermination de la teneur en impuretés dans le maïs (Zea mays, L.) et le sorgho
(Sorghum bicolor, L.)
Ta slovenski standard je istoveten z: CEN/TR 16875:2015
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TR 16875
TECHNICAL REPORT
RAPPORT TECHNIQUE
September 2015
TECHNISCHER BERICHT
ICS 67.060
English Version
Cereal and cereal products - Technical report of the
interlaboratory study for the determination of impurities
content in maize (Zea mays, L.) and sorghum (Sorghum
bicolor, L.)
Céréales et produits céréaliers - Rapport technique de
l'étude interlaboratoires pour la détermination de la
teneur en impuretés dans le maïs (Zea mays, L.) et le
sorgho (Sorghum bicolor, L.)
This Technical Report was approved by CEN on 27 July 2015. It has been drawn up by the Technical Committee CEN/TC 338.
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
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16875:2015 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Design of the study. 6
3.1 Conception and organization . 6
3.1.1 Method . 6
3.1.2 Participants . 6
3.1.3 Design and schedule of the study . 6
3.2 Product . 6
3.3 Fabrication . 6
3.4 Homogeneity and stability . 6
3.5 Form . 6
4 Statistics . 7
4.1 Methodology . 7
4.2 Statistical treatment. 7
5 Results of the interlaboratory study . 7
5.1 Validation of the raw results . 7
5.2 Detection of stragglers and outliers . 7
5.3 Stragglers and outliers detections . 9
5.4 Statistics . 10
5.5 Results . 10
Annex A (informative) Raw results . 16
A.1 Broken grains . 16
A.2 Grains impurities . 17
A.3 Sprouted grains . 18
A.4 Miscellaneous impurities . 19
A.5 Total impurities . 20
European foreword
This document (CEN/TR 16875:2015) has been prepared by Technical Committee CEN/TC 338 “Cereal
and cereal products”, the secretariat of which is held by AFNOR.
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.
Introduction
The principle of the determination of impurities is to separate all the groups of impurities from the
normal basic cereal grains of unimpaired quality by sieving and manual selection out of a subsample
and to quantify them. The amount of impurities and its constituent groups is important for health,
cleaning, milling and further processing aspects. For these reasons impurities content is a part of
contracts in grain trade and also of the grain intervention system of the EU.
At present a European standard for the determination of impurities in maize and sorghum (EN 16378)
has been developed.
An international interlaboratory trial for the determination of impurities in maize and sorghum was
accomplished in order to get information on the intra- and interlaboratory variability of the
determination of impurities content.
The technical report here describes the preparation and evaluation of the results of this interlaboratory
test.
1 Scope
The term impurities applies to all components of a grain sample that differ from the normal basic cereal.
It includes the following groups: broken grains, other cereals, grains damaged by pests, grains
overheated during drying, sprouted grains, extraneous seeds, unsound grains, extraneous matter and
impurities of animal origin.
The principle of the determination of impurities content is to separate all the groups of impurities from
the normal basic cereal grains of unimpaired quality by sieving and manual selection out of a subsample
and to quantify them. There are various problems in the determination of impurities:
Firstly, the identification of the different groups of impurities depends strongly on the experience and
the knowledge of the investigator.
Also experienced investigators can differ in their characterization of grains.
Finally, one is faced with the fact that grain, even after mixing, is rarely homogenous. In other words, if a
sample was divided by a sample divider into a number of portions, the amount of a specific group of
impurities in each portion could be different, even if absolutely no human or machine error occurred in
each determination.
These problems will result in variation of the results of the determination.
An international interlaboratory test for the determination of impurities, according to this standard and
involving 14 laboratories in 4 countries, was carried out with 5 maize and 3 sorghum samples. It was
asked to participants to make determination in duplicate.
Ten laboratories reported results for the complete sample set and two only for corns.
The test materials ranged between:
— 0,0 % and 2,7 % for broken grains;
— 0,2 % and 3,5 % for grain impurities;
— 0,0 % and 0,1 % for sprouted grains;
— 0,5 % and 3,3 % for miscellaneous impurities;
— 1,8 % and 8,7 % for total impurities.
The aim of the study is to determine the precision, repeatability and reproducibility of the method of
determination of impurities content in maize and sorghum samples.
The analyses were realized in March - April 2011.
It occurs according to ISO 5725:1994.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 16378, Cereals - Determination of impurities content in maize (Zea mays, L.) and sorghum (Sorghum
bicolor, L.)
3 Design of the study
3.1 Conception and organization
3.1.1 General
The interlaboratory comparisons of this test were designed according to the wishes of AFNOR and
organized by BIPEA.
3.1.2 Method
The participants made a commitment to apply strictly the described method and to prepare the samples
according to the method provided with the commitment letter for participating to the test: the standard
EN 16378.
3.1.3 Participants
Fourteen laboratories made a commitment to participate to the test. Twelve did answer.
3.1.4 Design and schedule of the study
Each laboratory received eight samples: 5 samples of corn and 3 samples of sorghums, according to a
blind distribution.
In order to take into account the sampling of the laboratory into the precision values, the laboratories
realized two analytical series on two sub-samples from each sample, leading to sixteen determinations
of impurities.
Tests were conducted between March, 1st and April, 26th, 2011.
In order to be as close as possible to repeatability conditions, the two sub-samples analyses has been
realized during a time as short as possible. The repeatability variance is an intra-laboratory variance.
However, in order to be easier to read, it is called repeatability mean in the report.
3.2 Product
In order to cover the scope of the method, the products analysed are maize mixes and sorghum mixes.
3.3 Fabrication
The samples are produced according to the following procedure:
Each batch is homogenized and divided in samples serials. This operation is made with a carousel. The
principle of turning spreading, that involves a progressive filling, ensures the homogeneity of the
product between each sample.
The samples of maize 1, 2 and 4 and the samples of sorgho 1 and 3 were of 500 g in paper bags. The
samples of maize 3 and 5 and the samples of sorgho 2 were of 1 kg in paper bags. The weights were
increased for some samples in order to integer the division step inside the laboratory.
3.4 Homogeneity and stability
On this test, no control was planned. However, homogeneity and stability were considered as sufficient
by the working group for the test, during its conception.
3.5 Form
In addition to final results, expressed in % of impurities, the weights values were requested to the
participants. The form sheet template is in A.2.
4 Statistics
4.1 Methodology
The precision parameters were calculated on the two sub-samples of each impurity category according
to the following plan.
Figure 1
4.2 Statistical treatment
The statistical treatment was carried out according to ISO 5725-2.
5 Results of the interlaboratory study
5.1 Validation of the raw results
The project leader realized the checks of the calculations of impurities contents from the weight values.
A laboratory seems not to have followed the method; it was excluded from the calculations of the
precision parameters (laboratory 7568).
A laboratory did not write correctly his results, it has a lack of traceability of its samples (laboratory
2190). The results of the corn 3 have been reported on the corn 2 form sheets, those of corn 4 on the
form sheet for corn 3 and those of corn 2 on the form sheet of corn 4.
The traceability and the results have been corrected.
5.2 Detection of stragglers and outliers
Stragglers and outliers det
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.