EN 16913:2017

SLOVENSKI STANDARD
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Ta slovenski standard je istoveten z: EN 16913:2017
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 16913
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2017
EUROPÄISCHE NORM
ICS 13.040.20
English Version
Ambient air - Standard method for measurement of NO₃ˉ,
SO₄²ˉ, Clˉ, NH₄⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ in PM2,5 as deposited
on filters
Air ambiant - Méthode normalisée pour le mesurage de  Außenluft - Messverfahren zur Bestimmung von NO₃ˉ,
NO₃ˉ, SO₄²ˉ, Clˉ, NH₄⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ dans la SO₄²ˉ, Clˉ, NH₄⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ in PM2,5 nach
fraction PM2,5 telle que déposée sur des filtres Abscheidung auf Filtern
This European Standard was approved by CEN on 27 February 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
C OM I TÉ E U R O P É E N D E N OR M A L I S A TI O N

E U R OP ÄI S C H E S K OM I TE E F Ü R N OR M U N G

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 16913:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
4 Symbols and abbreviations . 7
5 Principle . 8
6 Equipment . 8
7 Sampling . 9
8 Transport and storage . 10
9 Analysis . 10
10 Calculation of results . 12
11 Quality control . 14
12 Measurement uncertainty . 17
13 Artefacts and interferences . 18
14 Data recording . 19
Annex A (informative) Statistical analysis of anion and cation concentrations collected on
filters from field validation exercise . 20
A.1 General . 20
A.2 Analysis methodology . 20
A.2.1 General . 20
A.2.2 Calculating between- and within-laboratory variability . 20
A.2.2.1 Notation . 20
A.2.2.2 Data processing . 21
A.2.2.3 Outlier rejection . 21
A.2.2.4 Data normalization . 22
A.2.2.5 Analysis of variance . 22
A.2.2.6 Calculation of standard deviations . 23
A.2.3 Calculating between-sampler variability . 23
A.2.3.1 Notation . 23
A.2.3.2 Data processing . 24
A.2.4 Combined standard uncertainty . 25
A.3 Remarks . 25
A.4 Results . 25
A.4.1 Data set 1 – Between laboratory and internal laboratory variability . 25
A.4.2 Data set 2 – Between sampler variability . 26
A.4.3 Data set 3 – Uncertainty over the measured concentration range . 27
A.4.4 Detection limit . 31
A.4.5 Field Blanks . 31
Annex B (informative) Uncertainty budget . 33
Annex C (informative) Reagents . 36
C.1 General . 36
C.2 Anion determination by ion chromatography . 36
C.3 Cation determination by ion chromatography . 37
C.4 Cation determination by inductively coupled plasma optical emission spectrometry
(ICP-OES) . 38
C.5 Ammonium determination by photometry . 39
Annex D (informative) Other analysis methods used in the validation programme . 41
D.1 Inductively coupled plasma optical emission spectrometer system (ICP-OES). 41
D.2 Conductometry . 41
D.3 Photometry . 42
D.3.1 Equipment . 42
D.3.2 Preparation of calibration curve. 42
D.3.3 Analytical procedure . 42
Annex E (informative) Preparation of stock standard solution . 43
Annex F (informative) Sampling artefacts . 44
F.1 General . 44
F.2 Ammonium nitrate . 44
F.3 Chloride . 45
Bibliography . 46

European foreword
This document (EN 16913:2017) 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 December 2017, and conflicting national standards
shall be withdrawn at the latest by December 2017.
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.
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 organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
This European Standard describes how to measure a specified range of anions and cations in PM as
2,5
deposited on filters.
The EU Air Quality Directive 2008/50/EC [1] on ambient air quality and cleaner air for Europe requests
- 2- - +, + + 2+ 2+
the measurements of concentrations of NO , SO , Cl, NH Na , K , Mg , Ca in PM at rural
3 4 4 2,5
background locations. In Annex IV of the Directive, guidance for these measurements is given.
Measurements of anions and cations in PM are being performed by the EMEP programme, mainly by
using a filterpack with limited particle size selectivity. The cooperative programme for monitoring and
evaluation of long-range transmission of air pollutants in Europe (EMEP) was launched in 1977 as a
response to the growing concern over the effects on the environment caused by acid deposition. EMEP
was organized under the auspices of the United Nations Economic Commission for Europe (UNECE).
Today EMEP is an integral component of the cooperation under the Convention on Long-range
Transboundary Air Pollution.
Directive 2008/50/EC requires that measurements at rural sites, where appropriate, are coordinated
with the monitoring strategy and measurement programme of EMEP. Although, there are different
sampling procedures involved, a common approach is used for the analytical procedure.
In order to keep the agreement between existing EMEP data and data to be produced using this
European Standard as close as possible, the EMEP protocol has been taken as starting point for this
European Standard. This European Standard differs from the EMEP protocol in the sense that
measurement of anions and cations are done in PM , and that a number of critical parameters
2,5
(e.g. choice of filter material) are fixed.
Additional attention is given to harmonizing these critical parameters with elemental carbon/organic
carbon (EC/OC) measurements and with PM measurements as well, as sampling is usually done
2,5
simultaneously.
1 Scope
This European Standard specifies a method for the determination of the mass concentration of water
- 2- - + + +
soluble NO (nitrate), SO (sulphate), Cl (chloride), NH (ammonium), Na (sodium), K (potassium),
3 4 4
2+ 2+
Mg (magnesium), Ca (calcium) in PM as deposited on filters.
2,5
This European Standard describes the analytical procedures for determining anions and cations as part
of the PM particulate phase, sample extraction and analysis of anions and cations by ion
2,5
chromatography. Sampling onto filters will be done in accordance with EN 12341 for PM .
2,5
NOTE 1 Alternatively, cations, excluding ammonium, can be analysed by inductively coupled plasma optical
emission spectrometry (ICP-OES). Ammonium can also be analysed by photometry or conductometry.
This European Standard can be used for the measurements of anions and cations as required by
Directive 2008/50/EC. The method does not take into account the possible losses during sampling due
to evaporation.
- - +
NOTE 2 NO3 , Cl , NH4 are part of the volatile fraction of PM2,5, and the concentrations determined using this
- + -
standard can be used as minimum values for the concentrations of these ions in PM . NO , NH , Cl are usually
2,5 3 4
up to 30 % underestimated due to evaporational losses from the filter during sampling.
This European Standard may be used at rural and urban background sites and road sites that are in
accordance with the siting criteria of Directive 2008/50/EC.
This European Standard is applicable to the measurement of anion/cations in PM samples
2,5
corresponding to PM mass concentrations between approximately 1 μg/m (i.e. the limit of detection
2,5
of the standard measurement method (EN 12341) expressed as its uncertainty) up to 120 μg/m .
The validated range of the anion and cation concentrations based on the field validation measurements
is presented in Table 1.
Table 1 — Validated range of anions and cations
Component Minimum Maximum
3 3
μg/m μg/m
-
Cl 0,001 1,4
-
NO 0,002 29
2-
SO 0,05 13
+
Na 0,003 1,9
+
NH 0,04 11
+
K 0,003 0,49
2+
Mg 0,001 0,38
2+
Ca 0,002 0,72
See Annex A for the statistical analysis of the field validation measurements.
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 and definitions
For the purposes of this document, the terms and definitions given in EN 12341:2014 and the following
apply.
NOTE In particular, the following terms of EN 12341 are used in this document: calibration, combined
standard uncertainty, coverage factor, expanded uncertainty, PM, standard uncertainty, uncertainty (of
x
measurement).
3.1
field filter blank
filter that is taken through the same procedure as a sample, including transport to and from, and
storage in the field, and analysis, but is not used for sampling air
Note 1 to entry: The filter is taken from the same batch as used for sampling.
3.2
laboratory filter blank
unused filter that does not leave the laboratory and is taken through the same procedure as a sample
Note 1 to entry: The filter is taken from the same batch as used for sampling.
3.3
reagent blank
solution that contains all the reagents used during the analysis of the sample, but without the sample
and filter matrix
4 Symbols and abbreviations
For the purposes of this document, the following abbreviations apply.
EMEP Cooperative programme for monitoring and evaluation of long-range transmission of air
pollutants in Europe
CD Conductivity Detector
FEP Fluorinated Ethylene Propylene
HDPE High Density PolyEthylene
HPLC High Performance Liquid Chromatography
ICP-MS Inductively Coupled Plasma Mass Spectrometry
ICP-OES Inductively Coupled Plasma Optical Emission Spectrometry
NIST National Institute for Standards and Technology
PE Polyethylene
PFA Perfluoroalkoxy
PM particulate matter
PP Polypropylene
PTFE Polytetrafluoroethylene
5 Principle
- - 2- + + + 2+
This method allows the determination of anions (Cl , NO and SO ) and cations (Na , NH , K , Mg and
3 4 4
2+
Ca ) in PM collected on filters used for sampling ambient air. The method is divided into two main
2,5
parts: the sampling in the field and the analytical procedure in the laboratory.
During sampling, particles containing anions and cations are collected by drawing a measured volume
of air through a filter mounted in a sampler designed to collect the PM fraction of suspended
2,5
particulate matter. The loaded filter is transported to the laboratory, where the anions and cations are
extracted deionized water by ultrasonic extraction. The extraction solution is analysed separately for
anions and cations by ion chromatography.
NOTE Alternatively, cations, excluding ammonium can be analysed by inductively coupled plasma optical
emission spectrometry (ICP-OES). Ammonium can also be analysed by photometry or conductometry.
6 Equipment
6.1 Sampling equipment
The performance requirements of the sampling instrument are described in EN 12341, including
Annex B.
6.2 Laboratory equipment
6.2.1 General requirements
All surfaces in contact with the sample filters, sample and calibration solutions shall be made of inert
material with respect to the analytes measured. High density polyethylene (HDPE) is normally a
suitable material. However, always check the material with respect to the specific purpose, e.g. for the
storage of standard solutions as well as for the determination of elements at an ultra-trace level,
fluorocarbon polymer materials such as perfluoroalkoxy (PFA) or hexafluoro ethylene propene (FEP)
may be advantageous. If cations are to be analysed, do not use glassware.
Wash all labware thoroughly and rinse with deionized water before use.
NOTE Contaminated labware can be cleaned with hot tap water and alkaline detergent before being taken
through the normal cleaning procedure.
6.2.2 General labware
Ordinary labware like volumetric flasks, pipettes, dispensers, PE vessels for sample extraction, storage
bottles (PE) for standard solutions and test tubes.
6.2.3 Filtration equipment
Use syringe filters (e.g. cellulose acetate or nylon; pore size 0,45 μm) together with single use medical
syringes.
Alternatively, membrane filtration equipment (PE, PP or PTFE) and membrane filters of a median pore
size 0,45 μm can be used.
6.2.4 Ion chromatography system
In general, it consists of the following components:
— eluent reservoir, and a degassing unit;
— metal-free high performance liquid chromatography (HPLC) pump;
— sample injection system, incorporating a sample loop of appropriate volume (e.g. 0,02 ml) or
autosampler device;
— separator column, with the specified separating performance;
— conductivity detector (CD);
— recording device, e.g. a computer with software for data acquisition and evaluation;
— precolumns, if necessary;
— suppressor, if necessary.
7 Sampling
7.1 Filter material.
Quartz fibre filters shall be used for sampling.
It is recommended that filters used should be from a manufacturer who has determined the separation
efficiency of the filter material according to standard methods such as EN 13274-7 [10] or
EN 1822-1 [9].
The anion and cation content of the filter should be as low as possible because it is usually the case that
higher filter blank values lead to higher variability of the blank values.
Brand related restrictions cannot be made, because brand specific qualities are bound to change in time.
1)
+
Currently the use of Whatman® QMA should be discouraged because of the high Na blanks and the
1)
+
uncertainty to what level the water soluble Na per batch may vary. Pallflex® Tissuequartz and
1)
Munktell® MK360 are advised [2].
7.2 Sampling time.
Samples shall be taken for 24 h periods. In case of regulatory measurements filter exchange at midnight
is required in order to obtain a calendar daily basis.
+ - -
Due to evaporational losses, the yield of NH , NO and Cl on the filter is dependent on the start and
4 3
stop time of the 24 h sampling period [2, 3, 4]. With respect to the diurnal variation of temperature, the
lowest yield can be expected when filters are exchanged during relatively high temperature conditions
(afternoon) and the highest yield at cold conditions (early in the morning). Therefore, it is at
least important to have equal daily filter exchange times for sites that measure also PM mass
concentration.
1) Whatman® QMA, Pallflex® Tissuequartz and Munktell® MK360 are examples of suitable products available
commercially. This information is given for the convenience of users of this European Standard and does not
constitute an endorsement by CEN of these products.
NOTE The filter exchange time may differ per application for practical reasons:
— in case of manually operated measurements, which is often the case for EMEP, it is best to synchronize with
other measurement series preferably at a fixed time in the morning, i.e. 8 am;
— in case of PM measurements as part of a scientifically driven study, it is best to exchange filters early in the
morning just after the expected coldest time of the day.
7.3 Field sampling and type of sampler.
The sampling device shall be in accordance with EN 12341. It is acknowledged that the sampling
process determines the size fraction of the particulate matter, the retention of semi-volatile material,
and sorption of inorganic gases to the filter at the time of sampling.
7.4 Site types.
In Directive 2008/50/EC Annex IV the requirement for anions and cations measurements is set to
“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, traffic
related locations)". Hence, in view of consistency and comparability of methods this European Standard
is for the use at rural sites as well as other types of monitoring sites, including suburban, urban
background, urban roadside and industrial sites.
7.5 Filter environment during sampling.
The sampler can be located either indoors or outdoors. At this stage, no specific demands on
temperature control beyond those given in EN 12341 are given.
8 Transport and storage
8.1 Handling
Filters shall be handled with clean tweezers, away from contamination sources.
Transport of filters shall be performed in a clean container. Storage after sampling shall be performed
in individual clean containers.
8.2 Time and temperature limits
Filters shall not be kept longer than 16 days in the field. Transport and any laboratory storage shall be
carried out at temperatures below 23 °C. Within 28 d 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.
9 Analysis
9.1 Reagents
Use only reagents of recognized analytical grade (see Annex C).
Use deionized water with a resistivity equal to or greater than 18 MΩ.cm at 25 °C, filtered to exclude
particles larger than 0,45 µm.
9.2 Filter sub-sampling
For extraction of water-soluble constituents from PM samples, the whole filter can be used or a sub-
2,5
sample, representative of the filter as a whole, may be taken. This can be done by using an appropriate
cutting device to obtain an accurately defined part of the exposed area of the sampled filter.
If sub-samples are to be analysed, perform a homogeneity check at least once for each type of sampler
and for each type of sampling site (e.g. industrial, urban, traffic, rural).
9.3 Sample extraction
The filters are put into a sample tube and deionized water (9.1) is added.
The extraction volume shall be enough to cover completely the sample, typically at least 10 ml, for
47 mm filters.
The sample tubes shall be exposed in an ultrasonic bath for (30 ± 5) min to obtain complete extraction.
Extraction should be performed at room temperature (no heating or cooling).
9.4 Sample preparation
If any filter material is expected to be present in the extract, the extracts shall be filtered or centrifuged
prior to analysis to avoid problems with the analytical instrument.
NOTE To filter the sample solutions use, e.g. a disposable syringe filter (6.2.3).
9.5 Analysis of extracts
For the ion chromatography method, follow EN ISO 10304-1 [11] and EN ISO 14911 [12] for the
- 2- - + + + 2+ 2+
analysis of NO3 , SO4 , Cl , NH4 , Na , K , Mg , and Ca or the procedure described in chapter 4.1 of the
EMEP manual [5]. For other analytical methods, see Annex D.
The injection system of the ion chromatograph is rinsed with sample solution. A small volume of the
sample solution, typically less than 0,05 ml, is then introduced into the injection system of an ion
chromatograph. The sample is mixed with an eluent and pumped through the separation unit and
detection unit of the ion chromatograph, i.e. a precolumn, a separation column, a suppressor device and
a detector.
Match the matrices of the sample solutions, the calibration standard solutions and the reagent blank
solution.
The ion chromatograph shall be calibrated with standard solutions containing known concentrations of
the ions. At least five calibration solutions and one zero standard (reagent blank solution) shall be used
to generate a suitable calibration curve. Prepare calibration solutions with ion concentrations
distributed as evenly as possible over the expected working range.
Examples of the preparation of standard solutions are found in Annex C and Annex E.
NOTE 1 It can be advisable to match the matrix of the sample solutions, the calibration standard solutions and
the reagent blank solution also with the eluent before analysis.
Any other analytical method shown to be equivalent using the EC equivalence procedure may be used
[6].
NOTE 2 Further metal and metalloid constituents, including mineral dust constituents (e.g. Al, Zn, Fe), can be
analysed with ICP–OES after digestion.
10 Calculation of results
10.1 General
It is intended that the following formulae are used for the calculation of results.
10.2 Calculation of anion and cation mass concentration in ambient air
The mass concentration of any ion in ambient PM determined using this standard method may be
2,5
described by the following formula:
m
ion
γ = (1)
amb
V
amb
where
γ is the mass concentration of the ion in ambient air, in μg/m
amb
V is the volume of ambient air sampled, in m
amb
m is the laboratory filter blank corrected mass of the ion measured in the sample, in μg
ion
NOTE It is assumed that sampling is carried out according to EN 12341 and that collected PM is analysed as
received. Therefore, no term is included to account for any loss of volatile material during sampling, or for any
deviation from the sampling of PM by the standard method.
2,5
It is important to note that the ionic content of the laboratory blank filters used to sample the ambient
PM may be significant. It is therefore important that a blank correction is made for this value as shown
in Formula (2). Given that it is not possible to measure the blank content of the individual filters used to
perform sampling, it is important that at least 5 % of the laboratory blank filters from the same batch
are measured in order to obtain a mean blank value and the variability in this value.
Furthermore, assuming that the same sub-sample area is analysed for all laboratory filter blanks, the
laboratory filter blank corrected mass of each ion measured in the sample may be calculated by:
m x
m x
ext,,B ext B
ext,,S ext S ii
mm= −=m − (2)
ion ion, S ion,B
rr
SB
where
m is the mass of the ion in the sample (loaded filter), in μg
ion,S
m is the average mass of the ion in the laboratory filter blank, respectively, in μg
ion B
are the mass of extraction solution for the sample and the laboratory filter
m and m
ext S
ext,B
i
blank i, respectively, in g
are the mass fraction of the ion in the PM extract for the sample and the
x and x
est,S
ext,B
i
laboratory filter blank i, respectively, in μg/g
r and r are the ratio of sub-sampled filter area to the total loaded filter area for the
S B
2 2
sample and the laboratory filter blanks, respectively, in m /m
represents the average mass of the ion in the laboratory filter blank sub-
< m x >
ext,,B ext B
ii
samples, in μg
If filters are not sub-sampled prior to analysis then and will be equal to unity with no uncertainty
r r
S B
and may be neglected.
Furthermore, the mass fraction of each ion in the PM extract may be calculated for the sample and the
laboratory filter blanks by:
I
I
B
S i
and (3)
x = x =
ext,S ext,B
 
i
V V
cal cal
where
I is the peak area on the ion chromatogram for the relevant ion measured on the loaded filter,
S
in μS ⋅ min
is the peak area on the ion chromatogram for the relevant ion measured on a laboratory
I
B
i
blank filter, in μS ⋅min

is the gradient of calibration curve (sensitivity) produced by the ion chromatograph, in
V
cal
μS ⋅ min ⋅ g/μg
The calculation for x is applicable for a linear calibration curve only. Should this not be the case,
ext
suitable software should be used for the fit calculation.
10.3 Method detection limit
The method detection limit, m , expressed in μg, is defined as 3 times the standard deviation of the
MDL
measurements of laboratory blank filters:
n 2
mm−
( )
∑ blk ,i blk
i=1
m 3⋅ (4)
MDL
n−1
where
th
m is the mass expressed in μg of anions or cations measured on the i laboratory blank filter
blk,i
in a set of filters
n
m is the average expressed in μg of n measurements of m
blk blk
A minimum of ten filters is recommended for the calculation of m .
MDL
NOTE 1 This can be converted into a method detection limit in mass concentration terms by dividing m by
MDL
the nominal value of the volume of ambient air sampled during a normal sampling period.
NOTE 2 Alternatively, the method detection limit can be determined according to DIN 32645 [15] from the
calibration curve.
10.4 Repeatability
The repeatability is the closeness of agreement of successive measurements of the same measurand
carried out under the same conditions of measurement. Quantitatively this can be expressed as the
relative standard deviation of a set of repeat measurements, thus:
in= 2
II−
( )
∑ i
i=1
σ = (5)
r
n− 1
I
=
where
is the relative standard deviation of a set of n measurements in %
σ
r
I is the peak area on the ion chromatogram for the relevant ion generated from measurement i
i
is the average of n measurements of I
i
I
A minimum of ten measurements is recommended for the calculation of σ .
r
10.5 Drift in instrument sensitivity

The drift in the sensitivity of the ion chromatograph, ∆V , over a time, t, is given by:
cal

VV−
cal,t 0 cal,t t

∆V = (6)
cal

V
cal,t=0
where

is the measured sensitivity of the instrument at time t = 0
V
cal,t=0

is the measured sensitivity of the instrument at time t
V
cal,t=t

To express this quantity in percentage terms, the value 100 ∆V needs to be calculated.
cal
11 Quality control
11.1 Reagent blank
A reagent blank shall be analysed at least once in every set of samples as a part of normal laboratory
QA/QC programme. The reagent blanks are usually below the detection limits calculated from the
laboratory blank filters (see 10.3). If the reagent blanks are higher than the detection limit, necessary
steps shall be taken to identify the contamination sources and correct the procedure accordingly.
11.2 Field filter blank check
The field filter blank is used only for quality assurance purposes. If the field filter blank exceeds
significantly the average laboratory filter blank, investigate the reasons for this and take corrective
action.
11.3 Analytical repeatability
The relative standard deviation, of the measured analytical response in the centre of the calibration
σ
r
range based on 10 repeat measurements shall conform to the limits given below:
- - 2-
— Cl , NO , SO : σ < 5 %;
3 4
r
+ + + 2+ 2+
— NH , Na , K , Mg , Ca : σ < 5 %.
r
This check shall be performed as a minimum of once a year or every time significant changes are done
to the equipment.
==
11.4 Calibration
The calibration relationship derived from the 5 calibration solutions plus zero point solution shall have
an R coefficient of ≥ 0,99.
The calibration range shall cover the vast majority of the measured sample concentrations, and ideally
shall be centred at about the average measured sample concentration.
11.5 Ion chromatography analysis
Demonstrate that the ion chromatography is able to separate the peak of interest successfully by
ensuring that the peak resolution for successive peaks is greater than 1. The peak resolution may be
calculated thus:
tt−
2 1
R= 2 (7)
w + w
where
R is the peak resolution
t1 is the retention time of the first peak, in s
t is the retention time of the second peak, in s
w is the peak width on the time axis of the first peak, in s
w is the peak width on the time axis of the second peak, in s
NOTE Peak widths are measured at the base of each peak, and are calculated by constructing isosceles
triangles over the Gaussian peak shapes.
11.6 Sub-sample repeatability
If sub-samples are analysed, the relative standard deviation, σ , of the measurements of single
r
extractions of sub-samples from the same filter, as a measure of repeatability shall conform to the limits
given below:
- - 2-
— Cl , NO , SO : σ < 10 %;
3 4
r
+ + + 2+ 2+
— NH , Na , K , Mg , Ca : σ < 10 %.
r
This check shall be performed as a minimum of once a year or every time significant changes are done
to the equipment.
11.7 Method detection limit
Requirements for method detection limits, based on laboratory filter blanks, depend on the range of
concentrations measured. For measurements at rural background sites the method detection limit m
MDL
shall conform to the limits given below:
- - 2-
— Cl , NO , SO : m < 5 µg/filter (for 47 mm filters);
3 4 MDL
+ + + 2+ 2+
— NH , Na , K , Mg , Ca : m < 2 µg/filter (for 47 mm filters).
4 MDL
11.8 Certified reference solutions
Appropriate certified reference solutions shall be analysed to provide continuous validation for the
analysis step of the standard method and shall be prepared independently of the calibration standards.
If the determined concentrations are not within 10 % of the stated value, the source of the problem
shall be identified and rectified. Analysis of these reference solutions shall be performed when new
calibration standards have been prepared and after each calibration (every 20 to 30 samples).
11.9 External quality assessment
If users of this European Standard carry out analysis of anions and cations in particulate matter on a regular basis it is recommended that they
participate in relevant external quality assessment schemes or proficiency testing schemes.
12 Measurement uncertainty
Formula (1), (2) and (3) may be combined to give:

mI
mI
ext,B B

ext,S S ii
γ= − ⋅ (8)

amb

rr
VV⋅

SB
cal amb


An individual laboratory may produce an assessment of the uncertainty of any individual measurement by performing a full ISO GUM treatment
[14] on Formula (8). Assuming the mass of extraction solution m for each laboratory filter blank i is nominally the same (and equal to m ),
ext,B ext,B
i
uy
( )
c amb
this yields a combined relative standard uncertainty in the measured ambient mass concentration, , of:
y
amb
2 2
   
2 ur( ) 2 ur( )
2 2 2 2 2 S 2 22 2 2 B
   
r I um( )++m u ()I m I + r I um( )+ m u (I )+ m I
( ) ( )
B S ext,,S ext S S ext,S S S B ext,B ext,B B ext,B B
 22  
2 2

rr
u (γ ) uV() uV( )
 S   B 
c amb cal amb
++ (9)
2  22
γ
VV
amb
r m I − rm I cal amb
( )
B ext,,S S S ext B B
where
u(xi) is the estimated standard uncertainty in each variable xi in Formula (9).
(x = m , m ,l , r ,r or V )
i ext,S ext,B s s B amb
=
If filters are not sub-sampled prior to analysis then rr 1 and ur( ) ur( ) 0 .
SB SB
If the sub-sample area ( rr r ) and the mass of extraction solution are equal for loaded and
SB
laboratory blank filters ( rr r and mm m ), Formula (9) simplifies to:
SB ext,,S ext B ext
 22  
um() um()
ur() ur()
2 ext 22 2 ext 2 2
   
I ++uI() I + I + u (I )+ I
S S S B BB
 2 2   2 2 
2  2
m rm r
u (γ ) uV() uV( )
 ext   ext 
c amb cal amb
++
2 22

γ
VV
amb
II− cal amb
( )
S B
(10)
and in case II<< , Formula (10) can further be approximated to:
BS
2 2 2 22

u (γ ) u (m )(u I ) uI() uV( )(uV )
ur()
c amb ext S B cal amb
+ ++ + + (11)
2 2 2 2  2 2
γ
m Ir I V V
amb
ext S S cal amb
The relative expanded uncertainty, U , of the measurement result is then calculated by:
r
u ()γ
c amb
U = k (12)
r
γ
amb
where
k is the coverage factor to provide a 95 % level of confidence, usually assumed to be equal to 2

For an exemplar uncertainty budget, see Annex B.
Alternatively, the measurement uncertainty can be determined using the direct approach according to
EN ISO 20988 [13] (i.e. based on co-located measurements).
13 Artefacts and interferences
13.1 Sampling
According to the EMEP protocol, the most accurate measurements of anions and cations can be
obtained using “denuder-filterpack systems”. The use of online automated analysers may also minimize
the influence of sampling artefacts on the data accuracy. See Annex F for sampling artefacts.
13.2 Analysis
Various quartz fibre brands show on average satisfactory blank results. All components result generally
in concentrations below 0,1 µg/m . As the laboratory averaged blank concentration is subtracted from
the sample result, the measurement combined uncertainty is dependent on the standard deviation of
the blank rather than the blank level itself (Formula (12)). The standard deviations of all components
remain usually below 40 ng/m [2].
Any species with a retention time similar to that of the main ions could interfere when ion
-
chromatography is used. With the exception of NO , precipitation and filter extracts do normally not
contain such species. In some systems a negative water dip in the start of the chromatogram may
-
interfere with the Cl determination. This can be avoided by adding a small amount of concentrated
eluent to all samples and calibration standards to match the eluent concentration.
=
=
== ==
==
== ==
NOTE For coastal or marine sites, an interference between sodium and ammonium can occur, so the choice of
chromatographic column is critical.
14 Data recording
The following information shall be recorded:
— concentration of anions and cations in µg/m (referred to the ambient temperature and pressure);
— site type and identification;
— sampling date with start and end time;
— information on any additional treatment, e.g. equilibration for PM mass concentration
measurements;
— date of analysis;
— ambient temperature during sampling;
— place,
...