EN 16909:2017

Ambient air - Measurement of elemental carbon (EC) and organic carbon (OC) collected on filters

This European Standard gives guidance on the measurement of elemental carbon (EC) and organic carbon (OC) following the requirement for the networks of all EU member states to measure EC and OC in particulate matter from June 2010 at background sites according to the Council Directive 2008/50/EC on ambient air quality and cleaner air for Europe [1].
This European Standard describes the analytical procedures for determining EC and OC on quartz fibre filters as μg/cm2, and the subsequent calculation of concentrations as µg/m3. Sampling onto filters is to be done in accordance with EN 12341:2014 for PM2,5. The sampling process determines the size fraction of the particulate matter, the retention of semi-volatile material, and uptake/loss of volatile organic compounds on the filter at the time of sampling.
The same analysis method may also be used for smaller size fractions than PM2,5. Any possible additional artefacts for larger particles, e.g. pyrolysis or higher concentrations of carbonates, should be assessed.
The scope includes rural background, urban background, road side and industrial measurement sites, to allow the assessment of additional exposure of people in urban areas as stated in the objectives of the council directive and to achieve coherence in the European approach.
The applicable concentration range of the proposed method is limited by the optical correction and instrument applied in the analysis of EC and OC. This method was validated from 0,2 µg CEC/cm² and 1,8 µg COC/cm² to 38 µg CEC/cm² and 49 µg COC/cm² in the laboratory and to 16 µg CEC/cm² and 45 µg COC/cm² in the field.

Außenluft - Messung von auf Filtern gesammeltem elementarem Kohlenstoff (EC) und organisch gebundenem Kohlenstoff (OC)

Diese Europäischen Norm bietet eine Anleitung zur Messung von elementarem (EC) und organischem Kohlenstoff (OC) in Übereinstimmung mit den Anforderung der Messung von EC und OC in Staub durch die Messnetze aller EU-Mitgliedstaaten vom Juni 2010 an Hintergrundstandorten sowie gemäß der Richtlinie 2008/50/EG des Europäischen Parlaments und des Rates vom 21. Mai 2008 über Luftqualität und saubere Luft für Europa [1].
Die Europäischen Norm beschreibt die Analyseverfahren zur Bestimmung von EC und OC auf Quarzfaserfiltern in μg/cm2 und die anschließende Berechnung der Konzentrationen in µg/m3. Die Probenahme auf den Filtern soll für PM2,5 nach EN 12341:2014 erfolgen. Beim Probenahmeprozess werden die Korngrößenfraktion des Staubs, die Retention von mittelflüchtigem Material sowie die Aufnahme von/der Verlust an flüchtigen organischen Verbindungen auf/von dem Filter zum Zeitpunkt der Probenahme bestimmt.
Das gleiche Analyseverfahren darf auch für kleinere Korngrößenfraktionen als PM2,5 angewendet werden. Jegliche bei größeren Korngrößenfraktionen möglichen zusätzlichen Artefakte, z. B. Pyrolyse oder höhere Konzentrationen an Carbonaten, sollten beurteilt werden.
Der Anwendungsbereich umfasst Messstandorte mit ländlichem und städtischem Hintergrund sowie Messstandorte am Straßenrand und in Industriegebieten, um die Beurteilung der zusätzlichen Exposition von Menschen ín städtischen Gebieten entsprechend den Zielen der Richtlinie des Rates zu ermöglichen und Kohärenz im europäischen Ansatz zu erreichen.
Der anwendbare Konzentrationsbereich des empfohlenen Verfahrens wird durch die optische Korrektur und das zur Analyse des EC und des OC angewendete Gerät beschränkt. Dieses Verfahren wurde im Laboratorium für Werte von 0,2 µg • CEC/cm2 und 1,8 µg • COC/cm2 bis 38 µg • CEC/cm2 und 49 µg • COC/cm2 sowie im Feld für Werte bis 16 µg • CEC/cm2 und 45 µg • COC/cm2 validiert.

Air ambiant - Mesurage du carbone élémentaire (EC) et du carbone organique (OC) prélevés sur filtre

La présente norme donne des préconisations concernant le mesurage du carbone élémentaire (EC) et du carbone organique (OC) dans le cadre de l’application de la Directive 2008/50/CE du Conseil concernant la qualité de l’air ambiant et un air pur pour l’Europe [1], qui exige de tous les réseaux, depuis juin 2010, et pour tous les États membres de l’Union européenne, le mesurage des concentrations en carbone élémentaire et en carbone organique dans la matière particulaire au niveau de sites de fond.
La présente norme décrit les modes opératoires d’analyse pour le dosage, en μg/cm2, du carbone élémentaire et du carbone organique sur des filtres en fibre de quartz et le calcul ultérieur des concentrations, en μg/m3. L’échantillonnage sur filtre doit être effectué conformément à l’EN 12341:2014 pour la PM2,5. Le procédé d’échantillonnage détermine la fraction granulométrique de la matière particulaire, la rétention de la matière semi-volatile et l’absorption/désorption des composés organiques volatils sur le filtre lors de l’échantillonnage.
La même méthode d’analyse peut également être utilisée pour des fractions granulométriques inférieures à celle de la PM2,5. Tout artéfact supplémentaire éventuel de particules de plus grande taille, par exemple dû à la pyrolyse ou à des concentrations significativement élevées en carbonates, doit être évalué.
Le domaine d’application comprend les sites de mesurage dans les zones de fond rurales ou urbaines, les zones de proximité automobile et les zones industrielles, afin de permettre l’évaluation de l’exposition supplémentaire des personnes dans les zones urbaines, conformément à l’énoncé des objectifs de la Directive du Conseil, et dans un souci de cohérence de l’approche européenne.
La gamme de concentration applicable pour la méthode proposée est limitée par le type de correction optique appliquée et par l’instrument utilisé lors de l’analyse du carbone élémentaire et du carbone organique. Cette méthode a été validée pour des gammes allant de 0,2 µgCEC/cm² et 1,8 µgCOC/cm2 à 38 µgCEC/cm2 et 49 µgCOC/cm2 en laboratoire, et pour des gammes montant à 16 µg CEC/cm2 et 45 µg COC/cm2 sur le terrain.

Zunanji zrak - Merjenje elementarnega ogljika (EC) in organskega ogljika (OC), zbranega na filtru

Ta evropski standard podaja smernice glede merjenja elementarnega ogljika (EC) in organskega ogljika (OC), s čimer izpolnjuje zahteve za omrežja vseh držav članic EU glede merjenja elementarnega ogljika in organskega ogljika v delcih od junija 2010 v neizpostavljenih okoljih v skladu z direktivo Sveta 2008/50/ES o kakovosti zunanjega zraka in čistejšem zraku za Evropo [1].
Ta evropski standard opisuje analitične postopke za določanje elementarnega ogljika in organskega ogljika na kremenovih filtrih kot μg/cm2 in posledični izračun koncentracij kot µg/m3. Vzorčenje na filtre se mora opraviti v skladu s standardom EN 12341:2014 za delce PM2,5. Postopek vzorčenja določa velikost delcev, zadrževanje polhlapnega materiala in absorpcijo/izgubo hlapnih organskih spojin na filtru v času vzorčenja.
Enaka metoda analize se lahko uporabi tudi za delce, manjše od delcev PM2,5. Priporočljivo je oceniti vse morebitne dodatne artefakte večjih delcev, npr. piroliza ali višje koncentracije karbonatov.
Na področje uporabe spadajo neizpostavljeno podeželsko in urbano okolje ter obcestna in industrijska merilna mesta, s čimer je omogočena ocena dodatne izpostavljenosti ljudi na urbanih območjih, kot je navedeno v ciljih direktive Sveta, in dosežena usklajenost evropskega pristopa.
Ustrezen razpon koncentracije pri predlagani metodi je omejen z optičnim popravkom in instrumentom, uporabljenim pri analizi elementarnega in organskega ogljika. Ta metoda je bila potrjena od 0,2 µg CEC/cm² in 1,8 µg COC/cm² do 38 µg CEC/cm² in 49 µg COC/cm² v laboratoriju ter do 16 µg CEC/cm² in 45 µg COC/cm² na terenu.

General Information

• Status: Published
• Publication Date: 28-Feb-2017
• Withdrawal Date: 29-Sep-2017
• ICS: 13.040.20 - Ambient atmospheres
• Technical Committee: CEN/TC 264 - Air quality
• Drafting Committee: CEN/TC 264/WG 35 - Standard method for measurement of OC and EC deposited on filters
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 06-Oct-2022
• Completion Date: 23-Sep-2025
• Directive: 1999/30/EC - Limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air
• Directive: 2008/50/EC - Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe
• Mandate: M/503 - Mandate to CEN, CENELEC and ETSI in support of the Implementation of the Ambient Air Quality Legislation
• Ref Project: SIST EN 16909:2017 - Ambient air - Measurement of elemental carbon (EC) and organic carbon (OC) collected on filters

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2017
Zunanji zrak - Merjenje elementarnega ogljika (EC) in organskega ogljika (OC),
zbranega na filtru
Ambient air - Measurement of elemental carbon (EC) and organic carbon (OC) collected
on filters
Außenluft - Messung von auf Filtern abgeschiedenem elementarem Kohlenstoff (EC) und
organisch gebundenem Kohlenstoff (OC)
Air ambiant - Mesurage du carbone élémentaire (EC) et du carbone organique (OC)
prélevés sur filtre
Ta slovenski standard je istoveten z: EN 16909:2017
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 16909
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2017
EUROPÄISCHE NORM
ICS 13.040.20
English Version
Ambient air - Measurement of elemental carbon (EC) and
organic carbon (OC) collected on filters
Air ambiant - Mesurage du carbone élémentaire (EC) et Außenluft - Messung von auf Filtern abgeschiedenem
du carbone organique (OC) prélevés sur filtre elementarem Kohlenstoff (EC) und organisch
gebundenem Kohlenstoff (OC)
This European Standard was approved by CEN on 2 January 2017.

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, Serbia, 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
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16909:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Abbreviations and acronyms . 8
4 Principle . 9
5 Materials and instruments . 9
5.1 Materials . 9
5.1.1 Gases . 9
5.1.2 Standard solution . 9
5.1.3 Other materials . 9
5.2 Instruments . 9
5.2.1 Sampling instruments . 9
5.2.2 Analytical instruments . 9
6 Sampling . 10
6.1 Filter material . 10
6.2 Preheating of filter material and handling . 10
6.3 Sampling duration and frequency. 10
6.4 Field sampling and type of sampler . 11
6.5 Site types . 11
6.6 Filter environment during sampling. 11
7 Transport and storage . 11
7.1 Handling . 11
7.2 Time and temperature limits . 11
8 Analysis . 11
8.1 General . 11
8.2 Thermal protocol . 12
9 Artefacts and interferences . 13
9.1 General . 13
9.2 Sampling . 13
9.3 Transport and storage . 13
9.4 Analysis . 14
10 Quality assurance/quality control (QA/QC) . 14
10.1 QA/QC for sampling parameters . 14
10.2 Field blank determination . 14
10.3 Laboratory blank determination . 15
10.4 Calibration for TC . 15
10.5 Long term stability and repeatability . 15
10.6 Other-QA/QC checks . 15
10.6.1 Use of quality control filters . 15
10.6.2 Calibration gas injections . 16
10.6.3 Calibration and checks on temperature sensors and optical systems . 16
10.6.4 Stability of the laser signal . 16
10.7 Applicable concentration range . 16
11 Calculation of concentrations of EC and OC . 17
12 Data recording . 17
13 Determination of measurement uncertainty . 18
Annex A (informative) Example of a logbook information . 21
Annex B (informative) An example of a standard operating procedure for analysing EC and
OC . 22
B.1 General . 22
B.2 Start-up . 22
B.3 Cleaning the system . 23
B.4 Running the instrument blank . 23
B.5 Running an external calibration standard . 23
B.6 Running an external long term calibration standard . 24
B.7 Running a EC/OC control sample and routine samples . 26
B.8 Shutdown of instrument . 26
Annex C (informative) Methods for the assessment of carbonate carbon . 28
Annex D (informative) Preparation of stock sucrose solutions and calibration standards . 30
Annex E (informative) Example for the determination of measurement uncertainty . 31
Annex F (informative) Statistical analysis of Organic Carbon (OC), Elemental Carbon (EC)
and Total Carbon (TC) concentrations collected on filters from field validation
exercise . 34
F.1 General . 34
F.2 Analysis methodology . 34
F.2.1 General . 34
F.2.2 Calculating between- and within-laboratory variability . 35
F.2.2.1 Notation . 35
F.2.2.2 Data processing . 35
F.2.2.3 Outlier rejection . 35
F.2.2.4 Data normalization . 36
F.2.2.5 Analysis of variance . 37
F.2.2.6 Calculation of standard deviations . 37
F.2.3 Calculating between-sampler variability . 38
F.2.3.1 Notation . 38
F.2.3.2 Data processing . 38
F.2.4 Combined standard uncertainty . 39
F.3 Remarks . 39
F.4 Results . 39
F.4.1 Data set 1 – Between laboratory and internal laboratory variability . 39
F.4.2 Data set 2 – Between sampler variability . 41
F.4.3 Data set 3a – Site specific ranking . 42
F.4.4 Data set 3B - Uncertainty over the measured concentration range. 47
Annex G (informative) Good example for an instrument blank laser signal for EUSAAR2 . 54
Figure G.1 — Good example for an instrument blank laser signal for EUSAAR2
including ± 3 % uncertainty limits . 54
Bibliography . 55

European foreword
This document (EN 16909:2017) has been prepared by Technical Committee CEN/TC 264 “Air quality”,
the secretariat of which is held by DIN.
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 September 2017, and conflicting national standards
shall be withdrawn at the latest by September 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
For air quality across the European Union to be assessed on a consistent basis, Member States need to
employ standard measurement techniques and procedures. The aim of this European Standard is to
present guidance on the measurement procedures to be followed when monitoring elemental carbon
(EC) and organic carbon (OC) collected on filters, following Council Directive 2008/50/EC on ambient
air quality and cleaner air for Europe [1]. This requires the chemical speciation of the sub-2,5 µm size
fraction of suspended particulate matter (PM ) in ambient air, as described in Annex IV.
2,5
The method set out in this European Standard provides operational definitions of the measured
quantities. Currently no traceable primary reference materials are available for EC and OC analysis and
no absolute scientific distinction between EC and OC is possible.
1 Scope
This European Standard is applicable for the measurement of elemental carbon (EC) and organic
carbon (OC) following the requirement for all EU member states to measure EC and OC in particulate
matter from June 2010 at background sites according to the Council Directive 2008/50/EC on ambient
air quality and cleaner air for Europe [1].
This European Standard describes the analytical procedures for determining EC and OC on quartz fibre
2 3
filters as μg/cm , and the subsequent calculation of concentrations as µg/m . Sampling onto filters is to
be done in accordance with EN 12341:2014 for PM . The sampling process determines the size
2,5
fraction of the particulate matter, the retention of semi-volatile material, and uptake/loss of volatile
organic compounds on the filter at the time of sampling.
The same analysis method may also be used for smaller size fractions than PM . Any possible
2,5
additional artefacts for larger particles, e.g. pyrolysis or higher concentrations of carbonates, should be
assessed.
The scope includes rural background and urban background sites. The measurement method can also
be applied to other site types, provided that the measurement range given below is not exceeded. The
use of this standard at all site types allows the assessment of additional exposure of people in urban
areas as stated in the objectives of the council directive and to achieve coherence in the European
approach.
The applicable concentration range of the proposed method is limited by the optical correction and
instrument applied in the analysis of EC and OC. This method was validated from 0,2 µg C /cm and
EC
2 2 2 2
1,8 µg C /cm to 38 µg C /cm and 49 µg C /cm in the laboratory and to 16 µg C /cm and 45 µg
OC EC OC EC
C /cm in the laboratory validation exercise and in the field validation exercise.
OC
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 12341:2014, Ambient air - Standard gravimetric measurement method for the determination of the
PM10 or PM2,5 mass concentration of suspended particulate matter
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms, definitions and abbreviations apply.
3.1 Terms and definitions
3.1.1
total carbon
TC
total quantity of carbon in a PM sample, including EC, OC and IC
Note 1 to entry: The amount of TC released from a PM sample in the specified thermal desorption and oxidation
process may be different from other analytical methods.
3.1.2
inorganic carbon
IC
fraction of carbon belonging to mineral species, including carbonates and other species
3.1.3
carbonate carbon
CC
fraction of carbon belonging to a carbonate compound
Note 1 to entry: Carbonate carbon (mainly CaCO3 and MgCO3) is viewed as the only inorganic carbon fraction
being released within the temperature range used in the thermal protocol.
3.1.4
elemental carbon
EC
fraction of total carbon in a PM sample, characterized by its non-volatility and chemical inertness
according to the specified thermal-optical protocol
Note 1 to entry: EC evolves from the sample by oxidation at elevated temperatures.
3.1.5
organic carbon
OC
fraction of total carbon in a PM sample that is volatilized or pyrolyzed in the non-oxidizing part of the
specified thermal-optical protocol
3.1.6
pyrolytic carbon
PC
fraction of organic carbon transformed by pyrolysis to elemental carbon, which is subsequently
corrected by the specified thermal-optical protocol
3.1.7
sampling artefact
ab(ad)sorption of gaseous species in (on) a PM sampling substrate (positive sampling artefact), and
volatilization of particulate species from a PM sampling substrate (negative sampling artefact)
3.1.8
PM
x
particulate matter suspended in air which passes through a size-selective inlet with a 50 % efficiency
cut-off at x µm aerodynamic diameter
3.2 Abbreviations and acronyms
PM Particulate Matter
AQD Council Directive 2008/50/EC on ambient air quality and cleaner air for Europe [1]
C Carbon determined as elemental carbon (EC)
EC
C Carbon determined as organic carbon (OC)
OC
EUSAAR2 EC/OC thermal optical protocol developed for the European Super-sites for
Atmospheric Aerosol Research
NIOSH US-National Institute for Occupational Safety and Health
IMPROVE US-Interagency Monitoring of Protected Visual Environments
TOT Thermal-Optical Transmittance
4 Principle
The method for measuring EC and OC in ambient PM samples collected on filters is based on the
volatilization and oxidation of carbon-containing PM components, the quantification of the carbon
released, with optical correction for the PC (the thermal-optical method). The general procedure
described is a thermal-optical transmittance (TOT) method.
5 Materials and instruments
5.1 Materials
5.1.1 Gases
— helium at least 99,999 % (% by volume),
— helium/oxygen (98:2 split) mixture with a maximum of impurities of 0,001 % (% by volume),
— helium/methane for internal calibration (e.g. 95:5) grade zero.
5.1.2 Standard solution
Carbon-containing standard solutions (typically sucrose), with an accurately determined concentration
range, e.g. from 0,4 μg C/μl to 5 μg C/μl. Calibrating standard solutions shall be prepared which cover
the concentration range of the samples to be analysed.
5.1.3 Other materials
— precision filter cutter of known area,
— quartz boat for the filter punch,
— stainless steel tweezers for sample handling,
— clean cutting surface (e.g. aluminium foil (uncoated) or quartz fibre filter),
— analytical syringe or pipette for calibration using standard solutions, e.g. 10 µl volume.
5.2 Instruments
5.2.1 Sampling instruments
The performance requirements of the sampling instrument are described in EN 12341:2014.
5.2.2 Analytical instruments
5.2.2.1 General
A thermal-optical analyser that allows EC and OC partitioning based on particulate carbon volatilisation
and oxidation, and optical correction of pyrolysis by using the light transmittance of the sample.
5.2.2.2 Performance requirements of the analytical instrument
Thermal-optical EC and OC analyser,
— the instrument lower detection limit shall be better than 0,2 µg C/cm of filter;
— the accuracy of TC measurements of an external standard (e.g. sucrose solution) shall be ± 10 %
or ± 0,5 µg C/cm (whichever is greater) over a working day (see 10.4).
6 Sampling
6.1 Filter material
Quartz fibre filters without binding materials shall be used.
Filters should be taken from large batches of nominally identical filters. Filters should be uniquely
identified and records kept to allow the identification of each filter with the manufacturer, purchase
date, and where possible, manufacturer’s batch and pack number.
NOTE 1 Any filter impurity may influence the analysis and possibly damage the instrument.
Before field measurements are started, the filter batch(es) shall be assessed for blank levels of EC and
OC using the measurement method to be used for the field samples.
NOTE 2 Typically only OC will be present in detectable quantities.
This assessment shall cover:
— average blank concentrations, and
— blank concentration variability.
Average OC content of the laboratory blanks shall not be above 2 µg C/cm and the standard deviation
of the OC content shall not be above 1 µg C/cm . No EC concentrations above the lower detection limit
shall be measured for the laboratory blank filters. Causes for high blank concentration should be
investigated and an appropriate action to eliminate them shall be taken (see 6.2). Specific causes of
blank variability can be expected, e.g. for the top and bottom filters of the manufacturers’ plastic
containers and they should be discarded.
The details of the assessment of the filter material are not specified further in this European Standard.
The procedure used and results shall be recorded. When the assessment gives cause for concern (as
discussed further below and in Clause 10), either the filters shall be preheated (see below) or
alternative batches of filters shall be obtained. Ongoing requirements for checks on the filter material
are given in Clause 10.
6.2 Preheating of filter material and handling
Preheating of the filters to reduce the OC content, e.g. to fulfil the requirements of 6.1, is permitted. If
preheating is used the blank value of the filters shall be determined according to 6.1. If filters are
preheated they shall be heated at a range of 400 °C to 850 °C for a minimum of 1 h.
NOTE The main reason not to preheat filters is to allow the use of the same filters for other purposes such as
PM2,5 mass measurement since firing can affect the handling and weighing results.
6.3 Sampling duration and frequency
No specific sampling duration or frequency is needed for this standard. In case of use in conjunction
with sampling in accordance with EN 12341:2014 and the AQD the sampling shall be from midnight to
midnight [13]. A sequential sampler (usually with 14 filters and one field blank) is allowed. Other
sampling durations may be chosen as needed for the measurement task.
In the case of measurements for the determination of annual average EC and OC concentrations, the
monitoring frequency set out in the 4th Daughter Directive 2004/107/EC for indicative concentration
measurements can be used.
6.4 Field sampling and type of sampler
The sampling device shall be in accordance with EN 12341:2014. It is acknowledged that the sampling
process determines the size fraction of the particulate matter, the retention of semi-volatile material,
and adherence of volatile organic compounds to the filter at the time of sampling.
6.5 Site types
In accordance to the 2008/50/EC Directive Annex IV and the requirements for EC and OC
measurements set therein, this European Standard is for rural background areas. It is also stated in
Annex IV that “this information is essential to judge the enhanced levels in more polluted areas (such as
urban back-ground, industry related locations or traffic related locations)“. Hence, in view of
consistency and comparability of methods, this standard is also for the use at other types of monitoring
site, including suburban, urban background, roadside and industrial sites, provided that the
measurement range of this method is not exceeded.
6.6 Filter environment during sampling
The sampler can be located either indoors or outdoors. No specific demands on temperature control
beyond those in EN 12341:2014 are given.
7 Transport and storage
7.1 Handling
Filters shall be handled with clean tweezers and clean cutter away from contamination sources (e.g.
cigarette smoke and organic solvent vapours – including solvent based pens).
Transport of filters shall be performed in a clean container. Storage after sampling shall be performed
in individual containers.
7.2 Time and temperature limits
Filters shall not be kept longer than 16 days in the field. Transport and any laboratory storage shall be
at temperatures below 23 °C. Within 28 days after sampling, filters shall either be analysed or
transferred to storage at temperatures below 5 °C. Filters can be stored at this condition for a longer
period.
NOTE OC concentration may change depending on handling. This may lead to different results with PM2,5
concentrations when these come from 2 filters that have been sampled in the same way but handled differently as
different changes of OC may have occurred.
8 Analysis
8.1 General
To quantify the content of EC and OC in an aerosol sample collected on a quartz fibre filter, thermal
volatilisation and oxidation at defined temperatures are used. Optical transmittance through the sample
is used for the correction of pyrolysis of OC occurring during the temperature steps in inert carrier gas.
CC may interfere with the determination of EC and OC (see 9.4). This standard uses the EUSAAR2
thermal optical transmittance protocol [6], the basic principles of which are described below.
A general scheme of the thermal optical analyser is given in Figure 1. The filter punch is placed into the
instrument’s oven, which is purged with helium. In the He mode (inert carrier gas), the oven’s
temperature is increased stepwise up to a first maximum 650 °C. OC either volatilises from the filter, or
chars in/on the filter and forms pyrolytic carbon (PC). In the He/O mode (oxidative carrier gas, 2 % O
2 2
in He), the instrument’s quartz oven is cooled to 500 °C, and a second temperature ramp is initialised.
The final temperature in He/O mode is 850 °C. In the He/O mode, EC and PC oxidize off the filter
2 2
punch. All gases evolved from the filter punch during He mode and He/O mode are carried into a
manganese dioxide oven where organic vapours are oxidized to carbon dioxide (CO ) gas. CO can be
2 2
detected directly (NDIR detector), or subsequently mixed with hydrogen gas (H ) and carried along
with the helium through a heated nickel catalyst which reduces the CO to methane (CH ). The CH is
2 4 4
then measured using a flame ionization detector (FID). Internal (e.g. methane) and external (e.g.
sucrose solution) carbon standards are used for calibration.
The laser transmittance signal (wavelength between 630 nm to 680 nm) shall be used to correct for
pyrolysis of OC to PC, which can take place when OC is heated in the He mode of the analysis. Not
correcting for pyrolysis leads to an underestimation of OC and a corresponding overestimation of EC.
This correction is made by continuously monitoring of the light transmittance through the filter punch.
As pyrolysis takes place (i.e. PC is formed), the transmittance drops, whereas it increases when EC
and/or PC oxidize(s). Hence, the correction determines the amount of carbon oxidized in the He/O
mode that is necessary to return the transmittance back to the initial value before pyrolysis started.
Therefore the split point is defined as the time point when the transmittance returns to the initial value.
This approach assumes either that PC oxidises before the EC originally on the filter, or that the light
transmission per unit mass of PC and EC is the same. These assumptions are unlikely to be met,
therefore causing an inherent uncertainty in the determination of the split point between EC and OC.
NOTE A laser transmittance signal wavelength of approximately 658 nm was used for the validation tests in
this standard.
Figure 1 — Simple scheme of a thermal-optical analyser
8.2 Thermal protocol
The thermal protocol of this standard is EUSAAR2 [6] with pyrolysis correction based on transmittance.
The temperature profile of the instrument shall be regularly calibrated see 10.6.3.
The analytical parameters for this protocol are listed below (Table 1). Instrumental parameters shall be
recorded in a logbook (e.g. as described in Annex A). Detailed exemplary descriptions of the analytical
procedures to be implemented are given as an example in Annex B.
Table 1 — Temperature steps and step durations for EUSAAR2
Mode Step T in °C, duration in s
He He 1 200, 120
He 2 300, 150
He 3 450, 180
He 4 650, 180
He No heating, 30
He/O 1 500, 120
a
He/O He/O 2 550, 120
2 2
He/O 3 700, 70
He/O2 4 850, 80
a
A mixture of 2 % O in He shall be used.
9 Artefacts and interferences
9.1 General
Generally, artefacts and interferences can occur during all steps measuring EC and OC. The most
important ones are:
— loss of semi-volatiles from the sample during sampling,
— additional uptake of OC during sampling,
— chemical reactions leading to losses and/or gains of OC during sampling,
— uptake or losses during transport or storage,
— pyrolysis of OC during analysis,
— carbonates in the sample detected as OC and/or EC,
— catalytic and other reactions during analysis affecting the OC versus EC split.
The first four of these effects are, to a large extent, common to measurements of PM, and shall be seen in
this context. Care should be taken to reduce the above artefacts as far as possible and reasonable.
9.2 Sampling
All sampling artefacts are inherent by convention and part of the EC and OC values according to this
standard. Sampling artefacts are mainly to be expected for OC and they can be significant (Chow et al.
[12]).
9.3 Transport and storage
Some positive (OC uptake by filters during transport and storage) or negative artefacts (OC losses
during transport and storage at elevated temperatures) can occur (Karanasiou et al. [15]).
The field and laboratory blank values (covered in Clause 10) generally show that a certain amount of
organic substance is bound to the quartz fibre filter and may accumulate on a filter by mechanisms
other than the active sampling. To reduce positive artefacts, samples shall be kept and handled away
from any contamination sources, e.g. organic liquids or aerosols.
9.4 Analysis
Known factors which influence the analysis are summarized below:
— Carbonate carbon (CC) will interfere with the organic carbon and/or the elemental carbon fraction.
If the filter punch subjected to analysis is still coloured after the analysis is finished, a significant
inorganic material content (soil/crustal material) can be suspected, and therefore inorganic carbon
interference is possible.
— Possible methods for assessing carbonate carbon are given in Annex C. No recommendations on
how often the CC assessment has to be performed can currently be given. Policies for the frequency
and timing of CC assessment are left to the responsible personnel. The results of the analysis shall
not be subtracted from the EC and/or OC measurement values but recorded to allow the estimation
of possible interferences.
— Light absorbing organic carbon can affect the laser correction as these species are removed from
the filter or pyrolyzed during He mode, causing changes in transmittance.
— Certain elements (e.g. Na and K), which can be present either as contaminants in the filter or as part
of the deposited material, have been shown to catalyse the removal of EC at lower temperatures,
thus affecting the thermal evolution of EC. This interference may be reduced by choosing filters
with low alkali metal contents.
— Oxygen donating species in the samples may interfere with the EC and OC analysis. Filters that
remain coloured after the analysis may be an indication of the presence of FexOy as such species.
10 Quality assurance/quality control (QA/QC)
10.1 QA/QC for sampling parameters
QA/QC for parameters such as sampled volume, size fraction, and losses of semi-volatiles shall be
performed by following the relevant procedures specified in EN 12341:2014, and other procedures
described in Clauses 7 and 8.
10.2 Field blank determination
For every 14 field samples there shall be at least one field blank, a nominally-identical filter to those
being sampled, which is prepared, transported to, stored in the sampler and transported back from the
monitoring site in the same way as the sampled filters. The full details of how the blank filters are
transported and kept at the monitoring site shall be recorded.
The field blanks shall be analysed for EC and OC in the same way as the field samples. The results shall
be recorded together with the field sample results.
In general field blank concentrations are not subtracted.
In cases where field blanks are subtracted a detailed justification should be provided.
NOTE Typical field blank values are up to 4 µg OC/cm .
10.3 Laboratory blank determination
The analysis of laboratory blanks serves two purposes:
— to check that the batches of filters used have low EC and OC content when they are purchased, and
— to check that the laboratory environment and laboratory procedures in use do not introduce
significant OC and/or EC contamination, either from material collected onto the blank filters, or
from contamination within the instrument.
These purposes will generally be addressed in parallel.
The requirement for initially assessing whether a specific filter type is suitable for EC and OC
monitoring is described in 6.1.
Alongside the filter checks given in 6.1, the laboratory procedures and environment will be checked by
analysing laboratory blanks. It is recommended that laboratory blanks are analysed at least once each
working week, or when very high field blank concentrations are found.
Details of the laboratory blank procedures are left to the responsible personnel. These procedures shall
be recorded together with the analytical data for the laboratory blanks.
10.4 Calibration for TC
Because there are no traceable primary reference materials available for atmospheric EC and OC,
calibration is currently limited to TC.
The principal calibration of the analytical system can be conducted via TC values provided by blank
filter samples spiked with calibration solutions of pure organic compounds such as sucrose. Further
information is given in Annex B and in the analytical instrument user’s manual. The instrument shall be
regularly calibrated for TC at least once every 12 months and after any major maintenance or
modification of the system.
The calibration shall be checked at least every measurement day (e.g. by analysis of a control filter – see
10.6.1 and/or sucrose spiked filter) with a quantity of TC relevant to the quantities in the field samples
being analysed. The results shall be within ± 10 % or ± 0,5 µg C/cm of the expected value, whichever is
greater. If not, the reasons have to be investigated (see Annex B) and the result of the investigation shall
be recorded with the other analytical data.
10.5 Long term stability and repeatability
The long term stability of the analytical system shall be determined from control filter measurements
(see 10.6.1) and from the spiked filter calibrations. A TC and OC long term stability of 10 % or ± 0,5 µg
C/cm , whichever is greater, difference from the initial mean of the first ten measurements can be
viewed as sufficient. An EC long term stability of 15 % or ± 0,5 µg C/cm difference, whichever is
greater, from the initial mean of the first ten measurements can be viewed as sufficient.
The repeatability is calculated as the relative standard deviation of ten measurements of the control
filter being conducted during one day. An accepted value for repeatability is 5 % or ± 0,5 µg C/cm
difference, whichever is greater. The instrument shall be regularly assessed for repeatability at least
once every 12 months and after any major maintenance or modification of the system.
10.6 Other-QA/QC checks
10.6.1 Use of quality control filters
A so-called “control filter” is a filter that has sampled ambient air by a high volume sampler, typically for
24 h. Ten punches of this filter are analysed so that a mean TC value and a mean EC/TC ratio are
determined as local reference values. These ten filter punches shall also be used to check for
homogeneous loading of the filter.
Analyses of new punches from the control filter, for example on each measurement day, give valuable
information about both the TC calibration and the consistent operation of the temperature profiles and
optical correction, and hence the EC versus OC split.
10.6.2 Calibration gas injections
Some analytical instruments incorporate an injection of calibration gas (e.g. such as 5 % methane in
helium) after each analytical run for internal calibration (to correct for any drift in the response of the
carbon detector). This provides a calibration of the flame ionization detector.
Other uses of calibration gases can be:
— calibration of the carbon detector,
— check of the efficiency of the catalyst and/or converter.
Action criteria are left to the user.
10.6.3 Calibration and checks on temperature sensors and optical systems
The temperature sensors including the temperature profile of the instrument shall be regularly
calibrated and the optical system checked at least once every 12 months and after any major
maintenance or modification of the system.
10.6.4 Stability of the laser signal
An unstable transmittance laser signal affects the determination of the EC/OC split point and potentially
alters the EC and OC concentrations (Karanasiou et al. [16]). The stability of the transmittance laser
signal shall be monitored during instrument blank analysis. The instrument blank analysis is conducted
by repeating the
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