SIST-TS CEN/TS 16861:2015
(Main)Plastics - Recycled plastics - Determination of selected marker compounds in food grade recycled polyethylene terephthalate (PET)
Plastics - Recycled plastics - Determination of selected marker compounds in food grade recycled polyethylene terephthalate (PET)
This Technical Specification specifies an analytical method for testing food grade, recycled polyethylene terephthalate (PET). This analytical method provides / is intended to be used as a quality control check. This test identifies and quantifies certain specified contaminants. Such contaminants are referred to as Marker Compounds.
The analytical method is applicable for use on PET samples and products at all stages in the recycling process and will therefore be useful to recycling companies producing commercial, recycled PET for food contact materials and articles, and the manufacturers of such articles.
This Technical Specification is without prejudice to any existing legislation.
NOTE Marker compounds are known to originate from two sources:
- from the PET material itself (i.e. residual monomers, degradation products or reaction/breakdown products);
- from food products that the PET has contacted during its first use.
WARNING: The use of this Technical Specification may involve hazardous materials, operations and equipment.
Persons using this Technical Specification should be familiar with normal laboratory practise. This document does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practises and to ensure compliance with any national regulatory conditions.
IMPORTANT - It is absolutely essential that tests conducted according to this Technical Specification be carried out by suitably trained staff.
Kunststoffe - Kunststoff-Rezyklate - Bestimmung von Markierungsstoffen in Polyethylenterephthalat (PET)-Rezyklaten für die Lebensmittelindustrie
Diese Technische Spezifikation legt ein Analysenverfahren für die Prüfung von Polyethylen-terephthalat (PET) Rezyklat für die Lebensmittelindustrie fest. Dieses Analysenverfahren bietet eine Überprüfung der Qualitätskontrolle/ist zur Anwendung als eine Überprüfung der Qualitätskontrolle vorgesehen. Mit dieser Prüfung werden bestimmte festgelegte Kontaminanten identifiziert und quantitativ bestimmt. Derartige Kontaminanten werden als Markierungsstoffe bezeichnet.
Das Analysenverfahren gilt für die Anwendung an PET Proben und -Produkten auf allen Stufen des Recyclingprozesses und ist daher für Recyclingunternehmen nützlich, die handelsübliche PET Rezyklate für Materialien und Gegenstände, die mit Lebensmitteln in Berührung kommen, produzieren, sowie für die Hersteller derartiger Gegenstände.
Diese Technische Spezifikation hat keine Verbindlichkeit für die bestehende Gesetzgebung.
ANMERKUNG Die Markierungsstoffe können ihren Ursprung aus zwei Quellen haben:
- aus dem PET Material selbst (d. h. Restmonomere, Abbauprodukte oder Reaktions-/Zerfallsprodukte);
- aus Lebensmitteln, mit denen PET bei seinem Erstgebrauch in Berührung kam.
WARNUNG Die Anwendung dieser Technischen Spezifikation kann den Umgang mit Gefahrstoffen, gefährlichen Tätigkeiten und Apparaturen einschließen.
Die Anwender dieser Technischen Spezifikation sollten mit der üblichen Laborpraxis vertraut sein. Dieses Dokument beabsichtigt nicht, sämtliche mit dessen Anwendung verbundenen Sicherheitsprobleme, soweit solche gegeben sind, anzusprechen. Es liegt in der Verantwortung des Anwenders, geeignete Maßnahmen für Gesundheits- und Arbeitsschutz zu ergreifen und deren Übereinstimmung mit sämtlichen nationalen gesetzlichen Vorschriften sicherzustellen.
WICHTIG : Es ist notwendig, dass Prüfungen nach dieser Technischen Spezifikation von entspre-chend qualifizierten Personen durchgeführt werden.
Plastiques - Plastiques recyclés - Détermination de compositions de traceurs sélectionnés dans les poly(téréphtalate d'éthylène) PET recyclés de qualité alimentaire
Polimerni materiali - Reciklirani polimerni materiali - Določevanje izbranih označevalcev spojin v hrani razreda recikliranega polietilenskega tereftalata (PET)
Ta tehnična specifikacija določa analizno metodo za preskušanje recikliranega polietilenskega tereftalata (PET), primernega za uporabo v prehrani. Ta analizna metoda zagotavlja/je namenjena uporabi v okviru kontrole kakovosti. Ta preskus določa in količinsko opredeljuje nekatera opredeljena onesnaževala. Takim onesnaževalom se reče označevalci spojin.
Analizna metoda je primerna za uporabo pri vzorcih in izdelkih iz PET v vseh fazah procesa recikliranja ter je zato koristna za reciklirna podjetja, ki proizvajajo komercialni reciklirani PET za materiale in izdelke, ki imajo stik z živili, ter za proizvajalce takih izdelkov.
Ta tehnična specifikacija ne posega v nobeno obstoječo zakonodajo.
OPOMBA: Označevalci spojin izhajajo iz dveh virov:
– iz samega materiala PET (tj. ostanki monomerov, razgradni produkti ali reakcijski/razpadni produkti);
– iz prehrambnih proizvodov, s katerimi je PET prišel v stik med prvo uporabo.
POZOR: Pri uporabi te tehnične specifikacije so lahko prisotni nevarni materiali, postopki in oprema.
Osebe, ki uporabljajo to tehnično specifikacijo, bi morale biti seznanjene z običajno laboratorijsko prakso. Ta dokument ne obravnava vseh morebitnih varnostnih težav, ki se nanašajo na njegovo uporabo. Za vzpostavitev ustreznih varnostnih in zdravstvenih praks ter za zagotovitev skladnosti z morebitnimi nacionalnimi regulativnimi pogoji je odgovoren uporabnik.
POMEMBNO: Bistvenega pomena je, da preskuse, ki se izvajajo v skladu s to tehnično specifikacijo, izvaja ustrezno usposobljeno osebje.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 16861:2015
01-september-2015
3ROLPHUQLPDWHULDOL5HFLNOLUDQLSROLPHUQLPDWHULDOL'RORþHYDQMHL]EUDQLK
R]QDþHYDOFHYVSRMLQYKUDQLUD]UHGDUHFLNOLUDQHJDSROLHWLOHQVNHJDWHUHIWDODWD 3(7
Plastics - Recycled plastics - Determination of selected marker compounds in food grade
recycled polyethylene terephthalate (PET)
Kunststoffe - Kunststoff-Rezyklate - Bestimmung von Markierungsstoffen in
Polyethylenterephthalat (PET)-Rezyklaten für die Lebensmittelindustrie
Plastiques - Plastiques recyclés - Détermination de compositions de traceurs
sélectionnés dans les poly(téréphtalate d'éthylène) PET recyclés de qualité alimentaire
Ta slovenski standard je istoveten z: CEN/TS 16861:2015
ICS:
13.030.50 Recikliranje Recycling
83.080.20 Plastomeri Thermoplastic materials
SIST-TS CEN/TS 16861:2015 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN/TS 16861:2015
TECHNICAL SPECIFICATION
CEN/TS 16861
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
June 2015
ICS 13.030.50; 83.080.20
English Version
Plastics - Recycled plastics - Determination of selected marker
compounds in food grade recycled polyethylene terephthalate
(PET)
Plastiques - Plastiques recyclés - Détermination de Kunststoffe - Kunststoff-Rezyklate - Bestimmung von
compositions de traceurs sélectionnés dans les Markierungsstoffen in Polyethylenterephthalat (PET)-
poly(téréphtalate d'éthylène) (PET) recyclés de qualité Rezyklaten für die Lebensmittelindustrie
alimentaire
This Technical Specification (CEN/TS) was approved by CEN on 19 April 2015 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
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/TS 16861:2015 E
worldwide for CEN national Members.
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Contents Page
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviations . 8
5 Principle . 8
6 Reagents . 8
6.1 Carrier gases for gas chromatography . 9
6.2 Solvent . 9
6.3 Standard solutions . 9
7 Apparatus . 9
7.1 Cryogenic mill . 9
7.2 Laboratory glassware . 9
7.3 Headspace gas chromatograph-mass spectrometer . 9
7.4 Capillary column . 9
7.5 Refrigerator and freezer . 9
7.6 Sieves . 10
7.7 Analytical balance . 10
8 Procedures . 10
8.1 Introduction . 10
8.2 Sample conservation . 10
8.3 Grinding of the PET samples. 10
8.3.1 General . 10
8.3.2 Initial preparation . 10
8.3.3 Cleaning of the cryogenic mill prior to use and in-between samples . 10
8.3.4 Cryogenic milling of the samples . 11
8.3.5 Sieving of ground samples . 11
8.4 Preparation of standard solutions . 11
8.4.1 General . 11
8.4.2 Stock solution A . 11
8.4.3 Stock solution B . 12
8.4.4 Spiking solution . 12
8.5 Blank determinations . 13
8.6 Preparation of sample vials . 13
8.7 Gas chromatographic analysis . 13
8.7.1 General . 13
8.7.2 Identification and quantification of analytes using the standard addition method . 13
9 Interference . 15
9.1 Interference during sampling and storage . 15
9.2 Interference due to co-elution . 15
10 Test report . 15
Annex A (informative) Representative chromatograms . 16
A.1 Total ion chromatogram of all six analytes . 16
A.2 Chromatograms of individual analytes in the selected ion monitoring mode . 16
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Annex B (informative) Example of instrument settings . 18
B.1 General . 18
B.2 Headspace sampler conditions . 18
B.3 Gas chromatography - mass spectrometry (GC-MS) – conditions . 19
B.4 Specific ions for selected ion mode (SIM) . 19
Annex C (informative) Performance characteristics . 20
C.1 General . 20
C.2 Limit of detection . 20
C.3 Limit of quantification . 20
C.4 Precision . 21
C.5 Accuracy . 21
C.6 Linearity . 22
C.7 Validation results . 22
Bibliography . 23
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Foreword
This document (CEN/TS 16861:2015) has been prepared by Technical Committee CEN/TC 249
“Plastics”, the secretariat of which is held by NBN.
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 announce this Technical Specification: 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.
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Introduction
In addition to drivers such as the recycling targets in the EU waste packaging Directive (94/62/EC)
and the economic cost of landfill taxes, there is a strong demand for recycled food grade plastic
products from packaging end-users who are concerned about their corporate image and promoting
their environmental responsibilities.
To ensure that recycling systems and plants used for recycling plastics from post-consumer waste for
food contact use are fit for purpose, the EU Commission published Regulation (EC) 282/2008 in
27th March 2008 (Recycled plastic materials and articles intended to come into contact with foods).
Two of the main purposes of Regulation (EC) 282/2008 are to define the conditions under which a
recycling process should be run and managed and how an application to EFSA (European Food
Safety Authority) to have the process authorized can be made. Even when plastics materials and
articles are produced using a recycling process which has been authorized by EFSA, it is essential
that they comply with the applicable food contact regulations, such as the Plastics Regulation (EU)
10/2011.
It can take a long time for validation to approve new recycling processes, and the “Challenge” test to
demonstrate the effectiveness of recycling processes, which is described in Regulation (EC) 282/2008
and ultimately required by EFSA, can be relatively expensive and time consuming. The analytical
method presented in this Technical Specification represents a novel, cost effective and relatively quick
quality assurance tool that would support new process development and assist organisations to
conform to the EC regulations on recycled plastics. Also, because of its flexibility with respect to
sample geometry, and small scale nature, the method can also be used in an ad hoc way to assess
the quality of a wide range of recycled PET samples and products, for example flake, pellets, and
products such as bottles and trays. The chemical compounds (called Marker compounds) for which
the method is validated fall into two categories: those that are representative of the PET plastic (e.g.
residual monomers), and the common flavour compound limonene.
This Technical Specification is intended to serve two main purposes:
— to provide an analytical method to enable recyclers and end users of recycled food grade
poly(ethyleneterephthalate) (PET) to identify and quantify the level of specific chemical
compounds. As such, it provides a means of providing a cost-effective, comparative assessment
of its quality in terms of the presence and level of these chemical contaminants;
— to provide a template for the development of analytical methods for the analysis of specific
“marker compounds” in other types of recycled food contact materials and articles, for example
high density polyethylene (HDPE).
This Technical Specification is intended to complement, but not to replace in any way, the existing
chemical analysis tests, such as the EFSA “Challenge” test, used to assess the efficiency of PET
recycling processes for food grade products, or the EU overall and specific migration tests on food
grade PET materials and articles using food products and/or food simulants. It is not intended to be
used as a pass or fail type method, but to enable changes in the level of specific chemical compounds
to be detected. This information could then be used in a number of ways, depending upon the exact
nature of the samples analysed, such as contributing to the information needed to justify a re-
examination of a recycling process using the EFSA “Challenge” test.
This Technical Specification is based on FP7 Project SupercleanQ.
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1 Scope
This Technical Specification specifies an analytical method for testing food grade, recycled
polyethylene terephthalate (PET). This analytical method provides / is intended to be used as a quality
control check. This test identifies and quantifies certain specified contaminants. Such contaminants
are referred to as Marker Compounds.
The analytical method is applicable for use on PET samples and products at all stages in the recycling
process and will therefore be useful to recycling companies producing commercial, recycled PET for
food contact materials and articles, and the manufacturers of such articles.
This Technical Specification is without prejudice to any existing legislation.
NOTE Marker compounds are known to originate from two sources:
— from the PET material itself (i.e. residual monomers, degradation products or reaction/breakdown
products);
— from food products that the PET has contacted during its “first use”.
WARNING – The use of this Technical Specification might involve hazardous materials,
operations and equipment.
Persons using this Technical Specification should be familiar with normal laboratory practise.
This document does not purport to address all of the safety problems, if any, associated with
its use. It is the responsibility of the user to establish appropriate safety and health practises
and to ensure compliance with any national regulatory conditions.
IMPORTANT – It is absolutely essential that tests conducted according to this Technical
Specification be carried out by suitably trained staff.
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.
CEN/TS 16011, Plastics - Recycled plastics - Sample preparation
EN ISO 472, Plastics - Vocabulary (ISO 472)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 472 and the following
apply.
3.1
analyte
substance to be determined
Note 1 to entry: In the context of this standard 'analyte' refers to the selected marker compounds (3.4) in the
PET sample.
3.2
diagnostic ion
selected fragment ion, molecular ion or other characteristic ion from the mass spectrum of the target
compound, chosen to provide good specificity and sufficient sensitivity
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3.3
laboratory sample
sample or subsample(s) sent to or received by the laboratory
Note 1 to entry: In the context of this standard 'laboratory sample' refers to sample of recycled PET, in the
form or flakes or pellets, or recycled PET food grade products intended to be used for the laboratory tests and
from which the test sample (3.9) will be removed.
Note 2 to entry: When the laboratory sample is further prepared (reduced) by subdividing, cutting, sawing,
coring, or by combinations of these operations, the result is the test sample. When no preparation of the
laboratory sample is required, the laboratory sample is the test sample. A test portion is removed from the test
sample for the performance of the test or for analysis. The laboratory sample is the final sample from the point of
view of sampling but it is the initial sample from the point of view of the laboratory.
Note 3 to entry: Several laboratory samples may be prepared and sent to different laboratories or to the same
laboratory for different purposes. When sent to the same laboratory, the set is generally considered as a single
laboratory sample and is documented as a single sample.
3.4
marker compound
chemical compound that is a typical contaminant present in post-consumer food grade PET and is the
type of species that an approved recycling process is expected to remove to a safe level
Note 1 to entry: The marker compound can originate from either the PET itself or the food products that it has
been in contact with during service.
3.5
recycled food grade PET
recycled PET in the form of flake or pellets from an extruder that has been recycled from post-
consumer food grade PET waste using a recycling process that has passed a “Challenge” test and
meets the requirements of the EU Regulation (EC) 282/2008
Note 1 to entry: Flake dimensions are typically 2 mm to 5 mm.
3.6
recycled food grade PET products
PET products, such as bottles and trays, which are intended for food use and have been
manufactured from recycled PET that meets the requirements of EU Regulation (EC) 282/2008
3.7
selected ion mode, SIM
measuring the intensity of selected diagnostic ions only
3.8
standard solution
solution of accurately known concentration, prepared using standard substances in one or several
ways
Note 1 to entry: In the context of this standard a 'standards solution is a solution containing a set of marker
compounds (analytical standards) prepared at a known concentration.
3.9
test sample
sample, prepared from the laboratory sample, from which test portions are removed for testing or
analysis
Note 1 to entry: In the context of this standard 'test sample' refers to aliquot of cryogenically ground and
sieved laboratory sample (3.3) which will be analysed for the marker compounds.
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4 Symbols and abbreviations
CAS Chemical abstracts service
GC-MS Gas chromatography with mass spectrometric detection
HDPE High density polyethylene
LOD Limit of detection
LOQ Limit of quantification
m/z Mass [m] to charge [z] ratio i.e. modulus of the quotient of the particle mass in u and
the particle charge in units of electronic charge
n Number
PDMS Polydimethyl siloxane
PET Polyethylene terephthalate
RMS Root mean square
RSD Relative standard deviation, in %
2
R The square of the Pearson product moment correlation coefficient through data
points in known y's and known x's
S/N Signal to noise ratio
5 Principle
The recycled PET sample is cryogenically ground using a laboratory-scale mill and sieved to a
prescribed particle size and then accurately weighed into a headspace vial and sealed. The vial is
heated and the headspace analysed by GC-MS using a capillary column of low polarity.
Concentrations of specific analytes (selected marker compounds) are quantified using a standard
addition headspace method. The specific analytes are listed in Table 1.
Table 1 — Selected analytes – i.e. marker compounds
Marker compound CAS-number
Acetaldehyde 75–07–0
2-Methyl-1,3-dioxolane 497–26–7
Ethanol 64–17–5
Ethyl acetate 141–78–6
Hexanal 66–25–1
Limonene 5989–27–5
6 Reagents
All reagents shall be of recognized analytical grade. Verify whether the reagents are applicable for this
specific purpose and free of interfering compounds.
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6.1 Carrier gases for gas chromatography
Carrier gas for gas chromatography shall be helium.
6.2 Solvent
Acetone for preparation of standard solutions (Propan-2-one, CAS 67-64-1).
6.3 Standard solutions
A mixed solution of the set of analytes listed in Table 1 shall be prepared at a known concentration of
4 mg/ml for each compound, in acetone (8.4).
7 Apparatus
7.1 Cryogenic mill
A cryogenically-cooled laboratory mill fitted with a 2 mm trapezoidal ring capable of operating at
16 000 r/min has been found suitable for this purpose.
7.2 Laboratory glassware
All glassware that comes into contact with the sample shall be free of the analytes and any interfering
compounds. The following glassware will be used in practice:
— headspace vials fitted with inert septa;
— volumetric flasks;
— volumetric pipettes;
— inert septum-sealed glass vial – e.g. 7 ml capacity;
— microlitre syringes.
7.3 Headspace gas chromatograph-mass spectrometer
Gas chromatograph shall be equipped with:
— a capillary column (according to 7.4);
— a mass spectrometric detector;
— an automated headspace sampler.
7.4 Capillary column
A capillary column shall be appropriate for sufficient resolution of the analytes in Table 1.
NOTE An example of a capillary column which has been found to be satisfactory for this type of work is one
that is 30 m long, has a diameter of 320 µm, and a 5 % phenyl 95 % PDMS stationary phase with a film thickness
of 3 µm.
7.5 Refrigerator and freezer
A laboratory freezer shall be used capable of maintaining a temperature of −10 °C to −20 °C.
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A laboratory refrigerator shall be used capable of maintaining a temperature of 2 °C to 8 °C.
7.6 Sieves
A fraction from the cryogenically ground PET is isolated for analysis by GC-MS by sieving the PET
through two sieves:
— a sieve having an aperture size of 500 µm;
— a sieve having an aperture size of 1 mm.
7.7 Analytical balance
All sample and reference standard weighing shall be carried out using a calibrated and properly
maintained balance capable of weighing to an accuracy of 0,01 mg.
8 Procedures
8.1 Introduction
The following instructions provide a standard addition sample with 4 µg/g of each marker compound
added.
8.2 Sample conservation
The laboratory and test samples shall be stored in a freezer between −10 °C and −20 °C in a
hermetically sealed container.
NOTE It is essential to store the PET samples in a freezer to maintain the stability and integrity of the
sample. This is particularly important in the case of acetaldehyde due to its volatility.
Samples should be analysed 'as soon as possible' after they have been identified to avoid any loss of
the marker compounds.
8.3 Grinding of the PET samples
8.3.1 General
The laboratory samples shall be cryogenically ground and prepared for the next stage (8.6).
The laboratory sample shall be cut into pieces suitable for the mill before grinding (8.3.2). The
cryogenically mill shall be cleaned before each use to prevent contamination (8.3.3). The grinding
shall take place under controlled conditions (8.3.4). After grinding, the sample shall be sieved (8.3.5)
as preparation for next stage (8.6).
8.3.2 Initial preparation
The laboratory PET samples shall be taken in accordance with CEN/TS 16011.
2
The laboratory PET sample shall be cut into pieces smaller than 100 mm prior to cryogenic milling.
8.3.3 Cleaning of the cryogenic mill prior to use and in-between samples
To avoid contamination of the samples the mill shall be cleaned, before each use, in accordance with
the following instruction:
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Clean at least all interior parts of the mill, in particular the collection pan, the rotor blades, the sieve
ring and any other parts such as the interior seals using a regime that includes both water based
detergents and, finally, organic solvents.
8.3.4 Cryogenic milling of the samples
The interior of the mill shall be cooled down prior to the addition of the sample, which itself shall have
been cooled. The grinding shall be done as follows:
— Take approximately 50 g of the laboratory sample.
— Cool the laboratory sample by immersing into a liquid nitrogen bath for at least 10 min.
— Add the cooled laboratory sample slowly when the mill is up to speed (e.g. 16 000 r/min).
— Keep the mill at cryogenic temperatures during operation.
NOTE 1 Further quantities of liquid nitrogen may be added. However, for safety reasons, it is strongly
advised that the mill is not rotating during addition of further nitrogen.
— Inspect the ground sample. Discard the ground sample if thermal degradation is visually
apparent.
NOTE 2 In case of thermal degradation and when grinding further laboratory samples it is advised to take
extra care to ensure both the sample and mill are sufficiently cooled.
8.3.5 Sieving of ground samples
The ground sample (8.3.4) shall be sieved as follows:
— Sieve the ground sample through a series of laboratory test sieves of 1 mm and 500 µm
apertures.
— Retain the portion with particles between 500 µm to 1 mm for analysis. This is the test sample.
If any storage is necessary prior to further preparation of samples (8.6) then store in accordance with
8.2.
8.4 Preparation of standard solutions
8.4.1 General
A spiking solution of the six analytes at a suitable concentration in acetone shall be prepared.
— First prepare stock solution A (8.4.2). This solution contains all analytes with the exception of
acetaldehyde. To prepare this solution the analytes shall b
...
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