SIST EN ISO 16017-2:2003

SLOVENSKI STANDARD
01-november-2003
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Indoor, ambient and workplace air - Sampling and analysis of volatile organic
compounds by sorbent tube/thermal desorption/capillary gas chromatography - Part 2:
Diffusive sampling (ISO 16017-2:2003)
Innenraumluft, Außenluft und Luft am Arbeitsplatz - Probenahme und Analyse flüchtiger
organischer Verbindungen durch Sorptionsröhrchen/thermische Desorption/Kapillar-
Gaschromatographie - Teil 2: Probenahme mit Passivsammlern (ISO 16017-2:2003)
Air intérieur, air ambiant et air des lieux de travail - Echantillonnage et analyse des
composés organiques volatils par tube a adsorption/désorption
thermique/chromatographie en phase gazeuse sur capillaire - Partie 2: Echantillonnage
par diffusion (ISO 16017-2:2003)
Ta slovenski standard je istoveten z: EN ISO 16017-2:2003
ICS:
13.040.01 Kakovost zraka na splošno Air quality in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16017-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2003
ICS 13.040.01
English version
Indoor, ambient and workplace air - Sampling and analysis of
volatile organic compounds by sorbent tube/thermal
desorption/capillary gas chromatography - Part 2: Diffusive
sampling (ISO 16017-2:2003)
Air intérieur, air ambiant et air des lieux de travail - Innenraumluft, Außenluft und Luft am Arbeitsplatz -
Echantillonnage et analyse des composés organiques Probenahme und Analyse flüchtiger organischer
volatils par tube à adsorption/désorption Verbindungen durch Sorptionsröhrchen/thermische
thermique/chromatographie en phase gazeuse sur Desorption/Kapillar- Gaschromatographie - Teil 2:
capillaire - Partie 2: Echantillonnage par diffusion (ISO Probenahme mit Passivsammlern (ISO 16017-2:2003)
16017-2:2003)
This European Standard was approved by CEN on 21 March 2003.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16017-2:2003 E
worldwide for CEN national Members.

CORRECTED  2003-07-16
Foreword
This document (EN ISO 16017-2:2003) has been prepared by Technical Committee ISO/TC 146
"Air quality" in collaboration with 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 November 2003, and conflicting national
standards shall be withdrawn at the latest by November 2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and
the United Kingdom.
Endorsement notice
The text of ISO 16017-2:2003 has been approved by CEN as EN ISO 16017-2:2003 without any
modifications.
INTERNATIONAL ISO
STANDARD 16017-2
First edition
2003-05-15
Indoor, ambient and workplace air —
Sampling and analysis of volatile organic
compounds by sorbent tube/thermal
desorption/capillary gas
chromatography —
Part 2:
Diffusive sampling
Air intérieur, air ambiant et air des lieux de travail — Échantillonnage et
analyse des composés organiques volatils par tube à
adsorption/désorption thermique/chromatographie en phase gazeuse
sur capillaire —
Partie 2: Échantillonnage par diffusion

Reference number
ISO 16017-2:2003(E)
©
ISO 2003
ISO 16017-2:2003(E)
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ii © ISO 2003 — All rights reserved

ISO 16017-2:2003(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Principle . 2
4 Reagents and materials. 2
5 Apparatus. 4
6 Sample tube conditioning . 5
7 Sampling . 5
8 Procedure. 6
8.1 Safety precautions . 6
8.2 Desorption and analysis. 6
8.3 Calibration. 8
8.4 Determination of sample concentration . 8
8.5 Determination of desorption efficiency . 8
8.6 Calibration of uptake rate. 8
9 Calculations. 9
9.1 Mass concentration of analyte . 9
9.2 Volume concentration of analyte . 9
9.3 Uptake rates. 10
10 Interferences. 10
11 Performance characteristics. 11
12 Test report. 11
13 Quality control. 11
Annex A (informative) Operating principles of diffusive sampling . 22
Annex B (informative) Description of sorbent types. 28
Annex C (informative) Guidance on sorbent selection. 29
Annex D (informative) Guidance on sorbent use . 30
Annex E (informative) Summary of data on overall uncertainty, precision, bias and storage. 31
Bibliography . 33

ISO 16017-2:2003(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16017-2 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 6, Indoor air.
ISO 16017 consists of the following parts, under the general title Indoor, ambient and workplace air —
Sampling and analysis of volatile organic compounds by sorbent tube/thermal desorption/capillary gas
chromatography:
 Part 1: Pumped sampling
 Part 2: Diffusive sampling
iv © ISO 2003 — All rights reserved

INTERNATIONAL STANDARD ISO 16017-2:2003(E)

Indoor, ambient and workplace air — Sampling and analysis of
volatile organic compounds by sorbent tube/thermal
desorption/capillary gas chromatography —
Part 2:
Diffusive sampling
1 Scope
This part of ISO 16017 gives general guidance for the sampling and analysis of volatile organic compounds
(VOCs) in air. It is applicable to indoor, ambient and workplace air.
This part of ISO 16017 is applicable to a wide range of VOCs, including hydrocarbons, halogenated
1)
hydrocarbons, esters, glycol ethers, ketones and alcohols. A number of sorbents are recommended for the
sampling of these VOCs, each sorbent having a different range of applicability. Very polar compounds
generally require derivatisation; very low boiling compounds are only partially retained by the sorbents and
can only be estimated qualitatively. Semi-volatile compounds are fully retained by the sorbents, but may only
be partially recovered.
This part of ISO 16017 is applicable to the measurement of airborne vapours of VOCs in a mass
3 3
concentration range of approximately 0,002 mg/m to 100 mg/m individual organic for an exposure time of
3 3
8 h, or 0,3 µg/m to 300 µg/m individual organic for an exposure time of four weeks.
The upper limit of the useful range is set by the sorptive capacity of the sorbent used and by the linear
dynamic range of the gas chromatograph column and detector or by the sample splitting capability of the
analytical instrumentation used. The lower limit of the useful range depends on the noise level of the detector
and on blank levels of analyte and/or interfering artefacts on the sorbent tubes. Artefacts are typically sub-
nanogram for well-conditioned Tenax GR and carbonaceous sorbents such as Carbopack/Carbotrap type
materials, carbonized molecular sieves such as Spherocarb and pure charcoals. Artefacts are typically at low
nanogram levels for Tenax TA and at 5 ng to 50 ng levels for other porous polymers such as Chromosorbs
and Porapaks.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 16000-1, Indoor air — Part 1: General aspects of sampling strategy

1) The sorbents listed in Annex B and elsewhere in this part of ISO 16017 are those known to perform as specified under
this part of ISO 16017. Each sorbent or product that is identified by a trademarked name is unique and has a sole
manufacturer; however, they are widely available from many different suppliers. This information is given for the
convenience of users of this part of ISO 16017 and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
ISO 16017-2:2003(E)
3 Principle
The diffusive sampler (or samplers) is exposed to air for a measured time period. The rate of sampling is
determined by prior calibration in a standard atmosphere (see 8.6). The organic vapour migrates down the
tube by diffusion and is collected on the sorbent (see Annex A). The collected vapour (on each tube) is
desorbed by heat and is transferred under inert carrier gas into a gas chromatograph equipped with a capillary
column and a flame ionization detector or other suitable detector, where it is analysed. The analysis is
calibrated by means of liquid or vapour spiking onto a sorbent tube.
Information on possible saturation of the sorbent bed, the effect of transients and the effect of face velocity is
given in Annex A. Annex A also explains the dependence of effective uptake rates on the concentration level
of pollutants and the time of diffusive sampling, for non-ideal sorbents, which results in different values being
given in Tables 1 and 2. Further detailed information on the theory of performance of diffusive samplers is
[1]
given in prEN 13528-3 .
4 Reagents and materials
During the analysis, use only reagents of recognized analytical reagent grade.
Fresh standard solutions should be prepared weekly, or more frequently if evidence is noted of deterioration,
e.g. condensation reactions between alcohols and ketones.
4.1 Volatile organic compounds.
A wide range of VOCs are required as reagents for calibration purposes, using either liquid spiking (4.7 and
4.8) or vapour spiking (4.4 to 4.6) onto sorbent tubes.
4.2 Dilution solvent, for preparing calibration blend solutions for liquid spiking (4.7).
The solvent should be of chromatographic quality. It shall be free from compounds co-eluting with the
compound(s) of interest (4.1).
NOTE Methanol is frequently used. Alternative dilution solvents, e.g. ethyl acetate or cyclohexane, can be used,
particularly if there is no possibility of reaction or chromatographic co-elution.
4.3 Sorbents, preferably of particle size 0,18 mm to 0,25 mm (60 mesh to 80 mesh).
Each sorbent should be preconditioned under a flow of inert gas by heating it overnight at a temperature at
least 25 °C below the published maximum for that sorbent before packing the tubes. They shall be kept in a
clean atmosphere during cooling to room temperature, storage, and loading into the tubes. Wherever possible,
analytical desorption temperatures should be kept below those used for conditioning. Tubes prepacked by the
manufacturer are also available for most sorbents and as such only require conditioning. Care should be
taken with the disposal of the sorbents, using normal laboratory practice.
NOTE A guide for sorbent selection is given in Annex C. Equivalent sorbents may be used. A guide to sorbent
conditioning and analytical desorption parameters is given in Annex D. In most cases the sorbents can be used for indoor
air measurements as well as for ambient air and workplace atmosphere measurements.
4.4 Calibration standards.
Calibration standards are preferably prepared by loading required amounts of the compounds of interest on
sorbent tubes from standard atmospheres (see 4.5 and 4.6), as this procedure most closely resembles the
practical sampling situation.
If this way of preparation is not practicable, standards may be prepared by a liquid spiking procedure (see 4.7
and 4.8) provided that the accuracy of the spiking technique is established by one of the following methods:
a) by using procedures giving spiking levels fully traceable to primary standards of mass and/or volume;
2 © ISO 2003 — All rights reserved

ISO 16017-2:2003(E)
b) confirmed by comparison with reference materials, if available;
c) confirmed by comparison with standards produced using standard atmospheres;
d) confirmed by comparison with results of reference measurement procedures.
4.5 Standard atmospheres, of known concentrations of the compound(s) of interest.
Prepare standard atmospheres by an independent method. Methods described in ISO 6141 and several parts
of ISO 6145 are suitable (see Bibliography). If the procedure is not applied under conditions that allow the
establishment of full traceability of the generated concentrations to primary standards of mass and/or volume,
or if the chemical inertness of the generation system cannot be guaranteed, the concentrations shall be
confirmed using an independent procedure.
4.6 Standard sorbent tubes, loaded by spiking from standard atmospheres.
Prepare loaded sorbent tubes by passing an accurately known volume of the calibration atmosphere through
the sorbent tube, e.g. by means of a pump. The volume of atmosphere sampled shall not exceed the
breakthrough volume of the analyte-sorbent combination. After loading, disconnect and seal the tube. Prepare
fresh standards with each batch of samples. Prepare standard atmospheres of mass concentrations
3 3
equivalent to 10 mg/m and 100 µg/m . For workplace air, load sorbent tubes with 100 ml, 200 ml, 400 ml, 1 l,
2 l, or 4 l of the 10 mg/m atmosphere. For ambient or indoor air load sorbent tubes with 100 ml, 200 ml,
400 ml, 1 l, 2 l, 4 l or 10 l of the 100 µg/m atmosphere.
4.7 Solutions for liquid spiking.
4.7.1 Solution containing approximately 10 mg/ml of each liquid component.
Accurately weigh approximately 1 g of substance or substances of interest into a 100 ml volumetric flask,
starting with the least volatile substance. Make up to 100 ml with dilution solvent (4.2), stopper and shake to
mix.
4.7.2 Solutions containing approximately 1 mg/ml of liquid components.
Introduce 50 ml of dilution solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.7.1 Make up to
100 ml with dilution solvent, stopper and shake to mix.
4.7.3 Solution containing approximately 100 µg/ml of each liquid component.
Accurately weigh approximately 10 mg of substance or substances of interest into a 100 ml volumetric flask,
starting with the least volatile substance. Make up to 100 ml with dilution solvent (4.2), stopper and shake to
mix.
4.7.4 Solution containing approximately 10 µg/ml of liquid components.
Introduce 50 ml of dilution solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.7.3. Make up to
100 ml with dilution solvent, stopper and shake to mix.
4.7.5 Solution containing approximately 1 mg/ml of gas components.
For gases, e.g. ethylene oxide, a high-level calibration solution can be prepared as follows. Obtain gas at
atmospheric pressure by filling a small plastic gas bag from a gas cylinder containing pure gas. Fill a 1 ml gas-
tight syringe with 1 ml of the pure gas and close the valve of the syringe. Using a 2 ml septum vial, add 2 ml
dilution solvent and close with the septum cap. Insert the tip of the syringe needle through the septum cap into
the dilution solvent. Open the valve and withdraw the plunger slightly to allow the dilution solvent to enter the
syringe. The action of the gas dissolving in the dilution solvent creates a vacuum, and the syringe fills with
solvent. Return the solution to the flask. Flush the syringe twice with the solution and return the washings to
the flask. Calculate the mass of gas added using the gas laws, i.e. 1 mole of gas at STP (standard
temperature and pressure: 273,15 K and 1 013,25 hPa) occupies 22,4 litres.
ISO 16017-2:2003(E)
4.7.6 Solution containing approximately 10 µg/ml of gas components
For gases, e.g. ethylene oxide, a low level calibration solution may be prepared as follows. Obtain pure gas at
atmospheric pressure by filling a small plastic gas bag from a gas cylinder. Fill a 10 µl gas-tight syringe with
10 µl of the pure gas and close the valve of the syringe. Using a 2 ml septum vial, add 2 ml dilution solvent
and close with the septum cap. Insert the tip of the syringe needle through the septum cap into the dilution
solvent. Open the valve and withdraw the plunger slightly to allow the dilution solvent to enter the syringe. The
action of the gas dissolving in the dilution solvent creates a vacuum, and the syringe fills with solvent. Return
the solution to the flask. Flush the syringe twice with the solution and return the washings to the flask.
Calculate the mass of gas added using the gas laws, i.e. 1 mole of gas at STP occupies 22,4 litres.
4.8 Standard sorbent tubes loaded by liquid spiking
Loaded sorbent tubes are prepared by injecting aliquots of standard solutions onto clean sorbent tubes as
follows. A sorbent tube is fitted into the injection unit (5.7) through which inert purge gas is passed at
100 ml/min and a 1 µl to 4 µl aliquot of an appropriate standard solution injected through the septum. After
5 min, the tube is then disconnected and sealed. Prepare fresh standards with each batch of samples. For
workplace air, load sorbent tubes with 1 µl to 5 µl of solution 4.7.1, 4.7.2 or 4.7.5. For ambient and indoor air,
load sorbent tubes with 1 µl to 5 µl of solution 4.7.3, 4.7.4 or 4.7.6.
5 Apparatus
Use ordinary laboratory apparatus and the following devices.
5.1 Sorbent tubes.
These tubes shall be compatible with the thermal desorption apparatus to be used (5.6). Typically, but not
exclusively, they are constructed of stainless steel tubing of dimensions 6,3 mm (1/4 in) OD, 5 mm ID and
90 mm long. Tubes of other dimensions may be used, but the uptake rates given in Table 1 are based on
these tube dimensions. For labile analytes, such as sulfur-containing compounds, glass-lined or glass tubes
(typically 4 mm ID) should be used. Mark one end of the tube, for example by a scored ring, about 10 mm
from the (diffusive) sampling end. Pack the tubes with preconditioned sorbents so that the sorbent bed will be
within the desorber heated zone and a consistent gap of about 14 mm is retained at the marked (diffusive)
end of the tube.
Uptake rates in Table 1 are given for tubes with a nominal air gap (between sorbent bed and diffusive end
[2]
cap) of at least 14 mm. In practice, packed tube dimensions vary , and tubes should be rejected where the
air gap (between stainless steel screen retaining the sorbent bed and the end of the tube) is outside the range
14,0 mm to 14,6 mm.
Tubes contain between 200 mg and 1 000 mg sorbent, depending on sorbent density, which is typically about
250 mg porous polymer, or 500 mg carbon molecular sieve or graphitized carbon. The sorbents are retained
by a stainless steel gauze at the diffusion end and an unsilanized glass wool plug and/or a second stainless
gauze at the other end.
5.2 Sorbent tube end caps.
The tubes shall be sealed, e.g. with metal screw cap fittings with PTFE seals.
5.3 Sorbent tube end caps for sampling.
The diffusive end cap is similar to 5.2, but allows the ingress of vapour through a metal gauze, the size of the
opening being the same as the cross-section of the tube.
Some versions of the end cap incorporate a silicone membrane next to the gauze.
4 © ISO 2003 — All rights reserved

ISO 16017-2:2003(E)
5.4 Syringes.
A precision 10 µl liquid syringe readable to 0,1 µl, a precision 10 µl gas-tight syringe readable to 0,1 µl and a
precision 1 ml gas-tight syringe readable to 0,01 ml.
5.5 Gas chromatograph, fitted with a flame ionization detector, photoionization detector, mass
spectrometric or other suitable detector capable of detecting an injection of 0,5 ng toluene with a signal-to-
noise ratio of at least 5 to 1, and including a gas chromatograph capillary column capable of separating the
analytes of interest from other components.
5.6 Thermal desorption apparatus, for the two-stage thermal desorption of the sorbent tubes and transfer
of the desorbed vapours via an inert gas flow into a gas chromatograph.
A typical apparatus contains a mechanism for holding the tubes to be desorbed whilst they are heated and
purged simultaneously with inert carrier gas. The desorption temperature and time is adjustable, as is the
carrier gas flow rate. The apparatus should also incorporate additional features, such as automatic sample
tube loading, leak-testing, and a cold trap in the transfer line to concentrate the desorbed sample (8.2). The
desorbed sample, contained in the purge gas, is routed to the gas chromatograph and capillary column via a
heated transfer line.
5.7 Injection facility for preparing standards by liquid spiking.
A conventional gas chromatographic injection port may be used for preparing sample tube standards. This
can be used in situ, or it can be mounted separately. The carrier gas line to the injector should be retained.
The back of the injection port should be adapted if necessary to fit the sample tube. This can be done
conveniently by means of a compression coupling with an O-ring seal.
6 Sample tube conditioning
Prior to use, tubes should be reconditioned by desorbing them at a temperature at or just above the analytical
desorption temperature (see Annex D) for 10 min with a carrier gas flow of at least 100 ml/min. The carrier gas
flow should be towards the diffusive sampling end to prevent recontamination of the sorbents. Tubes should
then be analysed, using routine analytical parameters, to ensure that the thermal desorption blank is
sufficiently small. If the blank is unacceptable, tubes should be reconditioned by repeating this procedure.
Once a sample has been analysed, the tube may be reused to collect a further sample immediately. However,
it is advisable to check the thermal desorption blank if the tubes are left for an extended period before reuse,
or if sampling for a different analyte is envisaged. Tubes should be sealed with metal screwcaps with
combined PTFE ferrule fittings and stored in an airtight container when not sampling or being conditioned.
NOTE The sorbent tube blank level is acceptable if interfering peaks are no greater than 10 % of the typical areas of
the analytes of interest.
7 Sampling
Select a sorbent tube (or tubes) appropriate for the compound or mixture to be sampled. Guidance on suitable
sorbents is given in Tables 1 and 2 and Annex B.
Immediately before sampling, remove the storage end cap from the marked end of the sample tube and
replace it with a diffusion end cap. Make sure the diffusion cap is properly seated and the other end cap is in
place.
When used for personal sampling, the tube(s) should be mounted in the breathing zone. When used for fixed-
location sampling, choose a suitable site; for indoor air in accordance with ISO 16000-1. For ambient air,
recommendations for site selection and for the protection of samples from adverse environmental conditions
[1]
are given in Annex A and prEN 13528-3 . Attention shall be paid to three main considerations: air velocity,
protection from precipitation, and security. More information is given in the next paragraph, in A.5 and
reference [1].
ISO 16017-2:2003(E)
Expose the sampling tubes only under conditions where the face velocity requirement can be expected to be
satisfied. For the tubes specified in 5.1 with end caps 5.3, wind speed (air velocity) has no influence. Other
devices may have different requirements, including also a minimum wind speed.
Instruments to measure wind speeds as low as 0,007 m/s are not commonly available, so the wind speed may
have to be measured indirectly. The user is also cautioned about the possible influence of very high wind
speeds (above 12 m/s) for which performance characteristics are currently unavailable.
The recommended exposure time for the VOCs covered by this part of ISO 16017 is 8 h for workplace
monitoring and four weeks for ambient and indoor air monitoring. Sampling over shorter periods is possible,
down to 30 minutes for workplace monitoring and one week for ambient and indoor air monitoring, but the
monitored concentration range will be changed accordingly. For example, for a 4-h sampling period, the
3 3
working range is approximately 0,004 mg/m to 200 mg/m .
NOTE  The working ranges specified in the Scope (see Clause 1) for 8 h and 4 weeks are not equivalent because they
depend on the choice of sorbent, different diffusive uptake rates and different practical applications.
Note and record the times, temperature and the barometric pressure at the start of the sampling period. At the
end of the sampling period, again note and record the time, temperature and barometric pressure.
Replace the diffusion end cap with a storage end cap and tighten the seal securely. The tubes should be
uniquely labeled. Solvent containing paints and markers or adhesive labels should not be used to label the
tubes.
If samples are not to be analysed within 8 h, place them in a clean, uncoated, sealed metal or glass container.
Record air temperature and barometric pressure periodically during sampling, if it is desired to express
concentrations reduced to specific conditions (9.1).
Field blanks should be prepared by using tubes identical to those used for sampling and subjecting them to
the same handling procedure as the sample tubes except for the actual period of sampling. For the field
blanks end caps are used instead of diffusion caps. Label these as blanks.
8 Procedure
8.1 Safety precautions
This part of ISO 16017 does not purport to address all of the safety concerns, if any, associated with its use. It
is the responsibility of the user of this part of ISO 16017 to establish appropriate health and safety practices
and determine the applicability of regulatory limitations prior to use.
8.2 Desorption and analysis
8.2.1 Desorption
The sorbent tube is placed in a compatible thermal desorption apparatus. Air is purged from the tube to avoid
chromatographic artefacts arising from the thermal oxidation of the sorbent or gas chromatographic stationary
phase. The tube is then heated to displace the organic vapours which are passed to the gas chromatograph
by means of a carrier gas stream. The gas flow at this stage shall be towards the diffusive sampling end, i.e.
the marked end of the tube should be nearest the gas chromatograph column inlet. The gas flowrate through
the tube should be on the order of 30 ml/min to 50 ml/min for optimum desorption efficiency. During the purge
period, care should be taken to minimize heating of the tube.
NOTE 1 For the initial air purge, it is usually necessary to use 10 × the tube volume (i.e. 20 ml to 30 ml) of inert gas to
completely displace the volume of air (2 ml to 3 ml) in the tube. However, if strongly hydrophilic sorbents are needed, it
may be necessary to employ a larger purge to reduce sorbed air and water to prevent ice formation blocking the cold trap.
6 © ISO 2003 — All rights reserved

ISO 16017-2:2003(E)
The desorbed sample occupies a volume of several millilitres of gas, so that pre-concentration is essential
prior to capillary GC analysis. This may be achieved using a small, cooled, secondary sorbent trap, which can
be desorbed sufficiently rapidly at low flowrates (< 5 ml/min) to minimize band broadening, and produce
capillary-compatible peaks. Alternatively, an empty secondary trap, or one containing an inert material such as
glass beads, may be used to preconcentrate the sample, but such traps typically require cooling to below
− 100 °C. Alternatively, the desorbed sample can be passed directly to the gas chromatograph (single-stage
desorption) where it shall be refocused. This typically requires a high phase ratio column (e.g. 5 µm film
thickness, 0,2 mm to 0,32 mm ID) and a sub-ambient starting temperature.
If a secondary sorbent cold trap is not available and if sub-zero capillary cryofocusing temperatures are used
to preconcentrate the analytes, water should be completely eliminated from the sample tube prior to
desorption in order to prevent ice formation which can block the capillary tubing and stop the thermal
desorption process.
NOTE 2 If a secondary cold trap is not available and optimum sample tube desorption flowrates of 30 ml/min to
50 ml/min are used, a minimum split ratio of 30:1 to 50:1 is typically required for operation with high-resolution capillary
columns. Single-stage thermal desorption may thus limit sensitivity.
Desorption conditions should be chosen such that desorption from the sample tube is complete, and no
sample loss occurs in the secondary trap, if used. Typical parameters are:
Desorption temp 250 °C to 325 °C
Desorption time 5 min to 15 min
Desorption flow rate 30 ml/min to 50 ml/min
Cold trap low + 20 °C to − 180 °C, depending on type of cold trap
Cold trap high 250 °C to 350 °C
Cold trap sorbent typically same as tubes, 40 mg to 100 mg, if used
Carrier gas helium
Split ratios Split ratios between the sample tube and secondary trap and between the secondary
trap and analytical column (if applicable) should be selected dependent on expected
atmospheric concentration. (See guidance from respective manufacturers of the
thermal desorption apparatus.)
NOTE 3 The desorption temperature depends on the analyte and the sorbent used. Recommendations for maximum
desorption temperatures for particular sorbents are given in Annexes A and C. Due to their potential thermal instability,
secondary and tertiary volatile amines and some polyhalogenated compounds having one or two carbon atoms specially
brominated compounds may suffer some thermal degradation.
8.2.2 Analysis
Set the sample flowpath temperature (transfer line temperature) high enough to prevent analyte condensation
but not so high as to cause degradation. Analytes sufficiently volatile to be present in the vapour phase in air
at ambient temperature do not usually require flowpath temperatures above 150 °C. However, some types of
apparatus may require higher temperatures.
Set up the gas chromatograph for the analysis of volatile organic compounds. A variety of chromatographic
columns may be used for the analysis of these compounds. The choice depends largely on which compounds,
if any, are present that might interfere in the chromatographic analysis. Typical examples are 50 m × 0,22 mm
fused silica columns with thick-film (1 µm to 5 µm) dimethylsiloxane or a 50 m 7 % cyanopropyl, 7 % phenyl,
86 % methyl siloxane stationary phase. Typical operating conditions for these columns are a temperature
programme from 50 °C to 250 °C at 5 °C/min, with an initial hold time of 10 min at 50 °C.
ISO 16017-2:2003(E)
The capillary column, or preferably a length of uncoated, deactivated fused silica, should be threaded back
through the transfer line from the thermal desorption apparatus to the gas chromatograph such that it reaches
as close as possible to the sorbent in the cold trap, or as close as possible to the tube in a single-stage
desorber. Internal tubing shall be inert and dead volumes shall be minimized. A split valve(s) is conveniently
placed at the inlet and/or outlet of the secondary trap. The split valve on the outlet of the secondary trap may
be located either at the inlet or the outlet of the transfer line. Split ratios depend on the application.
NOTE Lower split ratios are suitable for ambient (typically 1:1 to 10:1) and indoor air measurements (typically 1:1 to
20:1); higher split ratios for workplace air measurements (typically 100:1 to 1000:1).
Correspondence of retention times on a single column should not be regarded as proof of identity.
8.3 Calibration
Analyse each sorbent tube standard (4.6 or 4.8) by thermal desorption and gas chromatography.
Prepare a calibration graph by plotting the base-ten logarithm of the areas of the analyte peaks corrected for

blank levels on the vertical scale against the base-ten logarithm of the mass of the analyte, in micrograms, on

the sorbent tube standard corresponding to the solutions in 4.7 or atmospheres in 4.5.
8.4 Determination of sample concentration
Analyse the samples and sample blanks as described for the calibration standards in 8.3. Determine the peak
[3]
area and read from the calibration graph the mass of the analyte in the desorbed sample .
8.5 Determination of desorption efficiency
The efficiency of desorption should be checked by comparing the chromatographic response of a sorbent tube
standard (8.3) with that obtained by injecting aliquots of the standard solutions or the atmosphere directly into
the gas chromatograph. Thus, prepare a second calibration graph of peak area against mass of analyte as in
8.3, but using solutions 4.7 or atmosphere 4.6. This calibration should be the same, or nearly the same, as
that in 8.3. The desorption efficiency is the response of a tube standard divided by that of the corresponding
liquid standard injected directly. If the desorption efficiency is less than 95 %, change the desorption
parameters accordingly.
Some makes of thermal desorber do not have a direct liquid injection facility. In these cases, and when loaded
tubes are prepared from a calibration blend atmosphere, desorption efficiency should be checked by
comparing the calibration graph of the substance of interest (4.1) with that of n-hexane. The ratio of the slope
of the calibration graph of the substance of interest relative to that of n-hexane should be the same as the
relative response factor for that compound. Response factors for other compounds may be calculated
[1]
approximately from effective carbon numbers . If the ratio of the slopes of the calibration graphs do not agree
with the relative response factor within 10 %, change the desorption parameters accordingly.
8.6 Calibration of uptake rate
The uptake rates given in Tables 1 and 2 are for tubes with the dimensions given in 5.1 without a membrane
[4]
in the diffusion end cap (5.3). For other specifications, it may be necessary to follow EN 838 or
[5]
EN 13528-2 to determine the uptake rate.
[1]
NOTE Diffusive uptake rate is sometimes dependent on the choice of sorbent (see prEN 13528-3 ).
8 © ISO 2003 — All rights reserved

ISO 16017-2:2003(E)
9 Calculations
9.1 Mass concentration of analyte
Calculate the mass concentration of the analyte in the sampled air, in micrograms per cubic metre (µg/m ), by
means of Equation (1):
mm−
ab
ρ=×10 (1)
qt⋅
V
where
ρ is the mass concentration of analyte in the air sampled, in micrograms per cubic metre;
m is the mass of analyte present in the actual sample as found in 8.4, in micrograms;
a
m is the mass of analyte present in the blank tube, in micrograms;
b
q is the diffusive uptake rate, in cubic centimetres per minute (Table 1 or 8.6);
V
t is the exposure time, in minutes.
NOTE 1 If m and m are expressed in milligrams, the resultant mass concentration ρ will be in milligrams per cubic
a b
metre.
NOTE 2 If it is desired to express mass concentrations reduced to specified conditions, e.g. 25 °C and 101 kPa, then:
101 T + 273
ρρ=⋅ ⋅ (2)
c
p 298
where
ρ is the mass concentration of the analyte in air sampled, reduced to specified conditions, in
c
micrograms per cubic metre;
p is the actual pressure of the air sampled, in kilopascals;
T is the actual temperature of the air sampled, in degrees Celsius.
9.2 Volume fraction of analyte
Alternatively, calculate the content (volume fraction) of the analyte in air, in microlitres per cubic metre, by
means of the following equation:
mm−
ab 6
ϕ=×10 (3)
qt⋅
′
V
where
ϕ is the volume fraction of the analyte in air, in microlitres per cubic metre;
−1 −1 2)
q is the diffusive uptake rate in ng⋅(µl/l) ⋅min (Table 1 or 8.5) ;
V ′
−6
2) µl/l is often expressed in the non-ISO units ppm (= 10 ).
ISO 16017-2:2003(E)
t is the exposure time, in minutes.
NOTE If m and m are expressed in milligrams, the
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