Workplace air quality - Sampling and analysis of volatile organic compounds by solvent desorption/gas chromatography - Part 2: Diffusive sampling method

This part of ISO 16200 gives general guidance for the sampling and analysis of volatile organic compounds (VOCs)
in air.
This part of ISO 16200 is applicable to a wide range of VOCs, including hydrocarbons, halogenated hydrocarbons,
esters, glycol ethers, ketones and alcohols. A number of devices and sorbents are recommended for the sampling
of these VOCs, each sorbent having a different range of applicability.
NOTE Activated coconut shell charcoal is frequently used. Very polar compounds may require derivatization; very low
boiling compounds will only be partially retained by the sorbents and can only be estimated qualitatively. Semi-volatile
compounds will be fully retained by the sorbents, but may only be partially recovered.
This part of ISO 16200 is valid for the measurement of airborne vapours of VOCs in a concentration range of
approximately 1 mg/m3 to 1000 mg/m3 individual organic for an exposure time of 8 h.
The upper limit of the useful range is set by the sorptive capacity of the sorbent used and, subject to dilution of the
analysed solution, 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 sampling devices or in the
desorption solvent. Artefacts are typically sub-nanogram for activated charcoal, but higher levels of aromatic
hydrocarbons have been noted in some batches.

Qualité de l'air des lieux de travail - Échantillonnage et analyse des composés organiques volatils par désorption au solvant/chromatographie en phase gazeuse - Partie 2: Méthode d'échantillonnage par diffusion

Kakovost zraka na delovnem mestu - Vzorčenje in analiza hlapnih organskih spojin z desorpcijo s topilom in s plinsko kromatografijo - 2. del: Difuzijska metoda vzorčenja

General Information

Status
Published
Publication Date
30-Apr-2002
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-May-2002
Due Date
01-May-2002
Completion Date
01-May-2002

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INTERNATIONAL ISO
STANDARD 16200-2
First edition
2000-06-15
Workplace air quality — Sampling and
analysis of volatile organic compounds
by solvent desorption/gas
chromatography —
Part 2:
Diffusive sampling method
Qualité de l'air des lieux de travail — Échantillonnage et analyse des
composés organiques volatils par désorption au solvant/chromatographie
en phase gazeuse —
Partie 2: Méthode d'échantillonnage par diffusion
Reference number
ISO 16200-2:2000(E)
ISO 2000
---------------------- Page: 1 ----------------------
ISO 16200-2:2000(E)
PDF disclaimer

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be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this

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© ISO 2000

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic

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ii © ISO 2000 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 16200-2:2000(E)
Contents Page

1 Scope ..............................................................................................................................................................1

2 Normative references ....................................................................................................................................1

3 Principle..........................................................................................................................................................1

4 Reagents and materials ................................................................................................................................2

5 Apparatus .......................................................................................................................................................4

6 Sampling.........................................................................................................................................................5

7 Procedure .......................................................................................................................................................6

7.1 Desorption......................................................................................................................................................6

7.2 Analysis ..........................................................................................................................................................6

7.3 Determination of desorption efficiency.......................................................................................................6

7.4 Calibration of uptake rate .............................................................................................................................7

8 Calculations....................................................................................................................................................8

8.1 General............................................................................................................................................................8

8.2 Mass concentration of analyte .....................................................................................................................8

8.3 Volume concentration of analyte .................................................................................................................9

8.4 Uptake rates ...................................................................................................................................................9

9 Interferences ..................................................................................................................................................9

10 Precision and bias .........................................................................................................................................9

11 Storage and transport .................................................................................................................................10

12 Test report ....................................................................................................................................................10

13 Quality control..............................................................................................................................................10

Annex A (informative) Description of sorbent types .............................................................................................11

Annex B (informative) Diffusive sampling rates (cm /min)....................................................................................12

Annex C (informative) Equivalence of gas chromatographic stationary phases ...............................................20

Annex D (informative) Suppliers of charcoal-based organic vapour diffusive samplers..................................21

Annex E (informative) Specific information on sampler type A ...........................................................................22

Annex F (informative) Specific information on sampler type B ...........................................................................23

Annex G (informative) Specific information on sampler type C...........................................................................24

Annex H (informative) Specific information on sampler type D ...........................................................................25

Annex I (informative) Specific information on sampler type E.............................................................................26

Annex J (informative) Retention indices of selected VOCS on BP-1 and BP-10 phases...................................27

Bibliography..............................................................................................................................................................31

© ISO 2000 – All rights reserved iii
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ISO 16200-2:2000(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 3.

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 part of ISO 16200 may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

International Standard ISO 16200-2 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee

SC 2, Workplace atmospheres.

ISO 16200 consists of the following parts, under the general title Workplace air quality — Sampling and analysis of

volatile organic compounds by solvent desorption/gas chromatography:
� Part 1: Pumped sampling method
� Part 2: Diffusive sampling method
Annexes A to J of this part of ISO 16200 are for information only.
iv © ISO 2000 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 16200-2:2000(E)
Workplace air quality — Sampling and analysis of volatile organic
compounds by solvent desorption/gas chromatography —
Part 2:
Diffusive sampling method
1 Scope

This part of ISO 16200 gives general guidance for the sampling and analysis of volatile organic compounds (VOCs)

in air.

This part of ISO 16200 is applicable to a wide range of VOCs, including hydrocarbons, halogenated hydrocarbons,

esters, glycol ethers, ketones and alcohols. A number of devices and sorbents are recommended for the sampling

of these VOCs, each sorbent having a different range of applicability.

NOTE Activated coconut shell charcoal is frequently used. Very polar compounds may require derivatization; very low

boiling compounds will only be partially retained by the sorbents and can only be estimated qualitatively. Semi-volatile

compounds will be fully retained by the sorbents, but may only be partially recovered.

This part of ISO 16200 is valid for the measurement of airborne vapours of VOCs in a concentration range of

3 3

approximately 1 mg/m to 1000 mg/m individual organic for an exposure time of 8 h.

The upper limit of the useful range is set by the sorptive capacity of the sorbent used and, subject to dilution of the

analysed solution, 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 sampling devices or in the

desorption solvent. Artefacts are typically sub-nanogram for activated charcoal, but higher levels of aromatic

hydrocarbons have been noted in some batches.
2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of

this part of ISO 16200. For dated references, subsequent amendments to, or revisions of, any of these publications

do not apply. However, parties to agreements based on this part of ISO 16200 are encouraged to investigate the

possibility of applying the most recent editions of the normative documents indicated below. For undated

references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain

registers of currently valid International Standards.

EN 838:1995, Workplace atmospheres — Diffusive samplers for the determination of gases and vapours —

Requirements and test methods.
EN 1540, Workplace atmospheres — Terminology.
3Principle

Diffusive samplers consist of a sorbent separated from ambient air by some form of diffusion resistance, commonly

a controlled air gap and draught shield. The diffusive sampler (or samplers) is exposed to air for a measured time

© ISO 2000 – All rights reserved 1
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ISO 16200-2:2000(E)

period. The rate of sampling is determined by prior calibration in a standard atmosphere (see 7.4). Volatile organic

compounds migrate into the sampler by diffusion and are collected on the sorbent, normally activated carbon. The

collected vapour is desorbed by a solvent, typically carbon disulfide, and the solution is analysed with a gas

chromatograph equipped with a flame ionization detector, mass spectrometer or other selective detector.

4 Reagents and materials
During the analysis, use only reagents of recognized analytical reagent grade.
4.1 Volatile organic compounds
A wide range of VOCs are required as reagents for calibration purposes.
4.2 Desorption solvent

The desorption solvent, commonly carbon disulfide, should be of chromatographic quality. It shall be free from

compounds co-eluting with the substances of interest. Check the purity of each new batch of solvent.

NOTE Carbon disulfide is normally recommended for the desorption of non-polar compounds from activated carbon. For

polar compounds and mixtures of polar and non-polar compounds, there is no ideal universal desorption solvent.

Dichloromethane, methanol, higher alcohols, dimethylformamide and acetonitrile have been used as eluants, either singly or

mixed with each other or carbon disulfide. Dichloromethane may cause corrosion in the flame ionization detector.

The use of carbon disulfide desorption solvent can result in problems when polar analytes are collected from humid

atmospheres. Polar analytes may be soluble in a water phase which forms following desorption with carbon

disulfide when sufficient water is collected with the sample. A desorption solvent modifier shall be present at a

sufficient concentration to result in a homogeneous solution in desorbed samples; dimethylformamide may be

suitable for this purpose.
4.3 Sorbents
4.3.1 Activated charcoal

A particle size of 0,35 mm to 0,85 mm is recommended. Before packing the samplers, the charcoal shall be heated

in an inert atmosphere, e.g. high-purity nitrogen, at approximately 600 °C for 1 h. To prevent recontamination of the

charcoal, it shall be kept in a clean atmosphere during cooling to room temperature, storage and loading into the

samplers. Samplers prepacked by the manufacturer with pre-conditioned charcoal are also available and require

no further conditioning.

NOTE 1 Activated charcoal is usually processed from coconut shells. Some manufacturers recommend synthetic carbons as

alternatives to charcoal of biological origin (see annexes A and B).

NOTE 2 The sorptive capacity and desorption efficiency of different batches of activated charcoal may vary. Commercial

samplers, if used, should be purchased from the same batch and in sufficient number to provide consistent performance for a

definite period of time.
4.3.2 Other sorbents
Sorbents other than charcoal may be used for certain applications (see annex B).

NOTE A description of sorbent types is given in annex A. Equivalent sorbents may be used.

4.4 Calibration standards
4.4.1 General

Calibration blend solutions are required in order to compare the concentrations of desorbed solutions (7.2) with

those calibration standards in the gas chromatographic analysis. Such solutions should be prepared in a way that

is traceable to national standards.
2 © ISO 2000 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 16200-2:2000(E)

An internal standard, for example trifluorotoluene or 3-bromofluorobenzene, is optional. If used, it should not

interfere with the compounds of interest and it should not be removed from the elution solvent by the sorbent. In the

context of this method, the purpose of the internal standard is to correct for small variations in the injection volume.

The use of an internal standard as a surrogate to correct for desorption efficiency (e.g. n-propyl acetate in the

analysis of n-butyl acetate) is not recommended. Desorption efficiency should be determined directly with the

compounds of interest (7.3).

Storage times for calibration solutions vary according to application. Typically, carbon disulfide dilutions should be

prepared fresh weekly, or more frequently if evidence is noted of decomposition or evaporation.

NOTE In the analysis of complex mixtures, calibration blends of the pure compounds may be prepared before dilution with

the elution solvent. Examples of three calibration blends are listed here. These have been used in the analysis of mixed

solvents in paints, thinners, adhesives, cleaning fluids and miscellaneous commercial products. The components are arranged

to give resolved peaks on both BP-1 and BP-10 phases . Other blends may be more appropriate on different columns or in

other applications.

a) Blend 1 consists of: n-hexane, n-heptane, n-octane, n-decane, n-undecane, n-dodecane, benzene, toluene, o-xylene, p-

xylene, n-propylbenzene, isopropylbenzene, o-ethyltoluene, m-ethyltoluene, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,3,5-

trimethylbenzene, n-propyl acetate, n-butyl acetate, isobutyl acetate, butoxyethyl acetate.

b) Blend 2 consists of: isopropanol, isobutanol, n-butanol, 1-methoxy-2-propanol, butoxyethanol, toluene, ethylbenzene,

1,2,3-trimethylbenzene, ethyl acetate, ethoxyethyl acetate.

c) Blend 3 consists of: acetone, 2-butanone, 4-methylpentan-2-one, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclo-

hexanone, 4-methylcyclohexanone, isopropyl acetate, n-nonane, toluene.

In the above examples, calibration blends 1-3 are stable for at least one year when stored in dark glass bottles with

polytetrafluoroethylene (PTFE)-lined screw-caps at less than 4 °C.
4.4.2 Solution containing approximately 10 mg/ml of each liquid component

Weigh 1 g of the substance or substances of interest into a 100 ml volumetric flask, starting with the least volatile

substance. Make up to 100 ml with desorption solvent (4.2), stopper and shake to mix.

4.4.3 Solution containing approximately 1 mg/ml of liquid components

Introduce 50 ml of desorption solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.4.2. Make up to 100 ml

with desorption solvent, stopper and shake to mix.
4.4.4 Solution containing approximately 100����g/ml of each liquid component.

Weigh 10 mg of the substance or substances of interest into a 100 ml volumetric flask, starting with the least

volatile substance. Make up to 100 ml with desorption solvent (4.2), stopper and shake to mix.

4.4.5 Solution containing approximately 10����g/ml of liquid components

Introduce 50 ml of desorption solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.4.4. Make up to 100 ml

with desorption solvent, stopper and shake to mix.
4.4.6 Solution containing approximately 1 mg/ml of gas components

For gases, e.g. ethylene oxide, a high 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 precision 1 ml gas-tight syringe

BP-1 and BP-10 are examples of suitable products available commercially. This information is given for the convenience of

users of this part of ISO 16200 and does not constitute endorsement by ISO of these product. Equivalent products may be used

if they can be shown to lead to the same results. Annex C gives a non-exclusive list of products that are believed to be

equivalent.
© ISO 2000 – All rights reserved 3
---------------------- Page: 7 ----------------------
ISO 16200-2:2000(E)

(5.5) with 1 ml of the pure gas and close the valve of the syringe. Using a septum vial of suitable capacity, add 2 ml

desorption solvent and close with the septum cap. Insert the tip of the syringe needle through the septum cap into

the desorption solvent. Open the valve and withdraw the plunger slightly to allow the desorption solvent to enter the

syringe. The action of the gas dissolving in the desorption 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 l.

4.4.7 Solution containing approximately 10��g/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 precision 10 �l gas-tight syringe

(5.5) with 10 �l of the pure gas and close the valve of the syringe. Using a septum vial of suitable capacity, add

2 ml desorption solvent and close with the septum cap. Insert the tip of the syringe needle through the septum cap

into the desorption solvent. Open the valve and withdraw the plunger slightly to allow the desorption solvent to

enter the syringe. The action of the gas dissolving in the desorption 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 l.

4.5 Calibration blend atmospheres (for 4.6 and 7.4)

Prepare standard atmospheres of known concentrations of the compound(s) of interest by a recognized method.

See for example ISO 6141, ISO 6145 and ISO 6349 [1-3]. If the procedure is not applied under conditions that will

allow the establishment of full traceability of the generated concentrations to primary standards, confirm the

delivered concentrations using an independent procedure .
4.6 Standards for desorption efficiency (for 7.3)

Prepare standards by exposure of the samplers to the standard atmosphere (4.5) for an accurately known time.

After exposure, remove and seal the samplers.

If the generation of standard atmospheres is not practicable, the standards may be prepared by a liquid spiking

procedure, provided that the accuracy of the spiking technique is established by using procedures giving spiking

levels traceable to primary standards of mass and/or volume, or is confirmed by an independent procedure. This is

the procedure usually recommended by manufacturers; follow the manufacturer’s guidance for specific instructions.

These will vary significantly with the sampler type, and some examples are given in annexes E to J. In principle,

load the devices by injecting aliquots of standard solutions (4.4) of accurately known mass or volume at three or

more levels onto clean samplers, seal the samplers and leave to equilibrate.
5 Apparatus
Ordinary laboratory apparatus and the following.
5.1 Diffusive samplers.

A number of solvent-desorption diffusive samplers are available commercially. Information on available devices is

given in annex D and information of available sorbent types in given in annex A. Manufacturer-supplied data on the

characteristics of some typical sampler types are given in annexes E to J.

NOTE Self-packed samplers should not be used unless they can be shown to have reproducible and constant sampling

rates.

The desorption efficiency (D) for each batch of samplers shall be checked by one of the methods described in 4.6

and 7.3.

Some diffusive samplers have a back-up section, which can be used as a check on overload of the sampling

section.
4 © ISO 2000 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 16200-2:2000(E)

5.2 Gas chromatograph, fitted with a flame ionization (FID), 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

5:1.
NOTE Dichloromethane may cause corrosion in the FID of some instruments.

The gas chromatograph column shall be capable of separating the analytes of interest from other components.

Examples of suitable choices are 50 m x 0,22 mm fused silica columns with BP-1 or BP-10 stationary phases. A

typical film thickness is in the range 0,5�mto 2,0�m. Typical operating conditions for these columns might be

temperature programming from 50 °C to 200 °C at 5 °C/min with a carrier gas flowrate of 0,7 ml/min to 0,8 ml/min

helium. Annex C gives a list of equivalent phases.
5.3 Autosampler.

Autosamplers are commercially available with liquid-chilled sample trays, suitable for the analysis of volatile

solvents.
5.4 Volumetric glassware.

Precision volumetric flasks of an accurately known volume, to be used for the preparation of calibration blend

solutions (4.4). These should be obtained from suppliers issuing certificates of calibration traceable to primary

standards or be traceably calibrated in the laboratory by weighing of the solvent(s) applied.

5.5 Syringes (for 4.4.6 and 4.4.7).

Precision gas-tight syringes of accurately known volumes of 1,0 ml and 10�l, readable to 0,01 ml and 0,1�l

respectively.
6 Sampling

Select a diffusive sampler appropriate for the compound or mixture to be sampled. Guidance on the availability of

suitable samplers is given in 5.1. Annex B gives information on the availability of manufacturer-supplied diffusive

uptake rates for a range of VOCs and, where appropriate, any special conditions, e.g. a variation from the basic

device design. If a device is not listed for a particular VOC, it will be necessary to calibrate the device according to

7.4.

Follow the manufacturer’s guidance for specific sampling instructions. These will vary significantly with the sampler

type, and some examples are given in annexes E to J. In principle, any protective cover is removed before the

diffusive sampler is exposed to the target atmosphere, and the sampler is re-sealed again at the end.

When intended for personal sampling, mount the sampler in the breathing zone as defined in accordance with

EN 1540. When used for fixed-location sampling, choose a suitable sampling site. In either case, the sampler

should have unrestricted access to the sampled atmosphere, i.e. it should not be obscured by the wearer’s clothing

or other objects.

NOTE Some designs of diffusive sampler are affected by air velocity. See 7.4 for details.

The exposure time recommended for the VOCs covered by this part of ISO 16200 is normally 8 h for workplace

monitoring. If the maximum exposure time recommended is less than 8 h, this is indicated in annex B. Sampling

over shorter periods is possible, down to 30 min for workplace monitoring, but the limits of the measurable

concentration range increase accordingly. For example, for a 4-h sampling period, the concentration range is

3 3
approximately 2 mg/m to 2 000 mg/m .

Samplers should be uniquely labelled. Solvent-containing paints and markers or adhesive labels should not be

used to label the samplers.

Record air temperature and barometric pressure periodically during sampling if it is desired either to express

concentrations reduced to specific conditions (8.2) or to express concentrations as volume fractions (8.3).

© ISO 2000 – All rights reserved 5
---------------------- Page: 9 ----------------------
ISO 16200-2:2000(E)

Field blanks should be prepared by using samplers identical to those used for sampling and subjecting them to the

same handling procedure as the samples except for the actual period of sampling. Label these as blanks.

7 Procedure

CAUTION — This part of ISO 16200 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 16200 to establish appropriate

health and safety practices and determine the applicability of regulatory limitations prior to use.

7.1 Desorption

If samples are not to be analysed within 8 h, they shall be placed in a clean, uncoated, sealed metal or glass

container.

In each case, carry out the desorption in a clean atmosphere in a fume hood. Desorb the sample blanks in the

same way as the samples.

Follow the manufacturer’s guidance for specific desorption instructions. These will vary significantly with the

sampler type, and some examples are given in annexes D to H. In principle, the collected VOC is extracted from

the sorbent (4.3) with a suitable solvent (4.2). In some cases, the desorption is done without disassembling the

device; in others, the sorbent is removed and desorbed in a separate vessel.
If there is a back-up section of sorbent, this should be desorbed separately.

NOTE In some circumstances, a higher D may be obtained with ultrasonic extraction as opposed to mechanical shaking.

7.2 Analysis

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 (see 5.2). The choice will depend largely on which

compounds, if any, are present that might interfere in the chromatographic analysis.

Inject a known fixed volume (1 μl to 5 μl) of each standard solution (4.4) into the gas chromatograph. A

standardized injection technique should be used so that repeatable peak heights or areas are obtained. Typically,

for a series of replicate injections, the relative standard deviation should be better than ± 2 %.

NOTE Autosamplers normally achieve better than ± 1 %.

Inject the same fixed volume of solution from the desorbed sample into the gas chromatograph. Read from the

calibration graph the concentration of the analyte in the desorbed sample. Analyse the sample blank and the

samples used to determine desorption efficiency in the same way.

Correspondence of retention time on a single column should not be regarded as proof of identity. The retention

indices of about 160 VOCs on BP-1 and BP-10 phases are given in annex K. They are a useful guide to elution

order on these phases or their near equivalent, but are not definitive, since exact values depend on temperature

programme, carrier flowrate and other factors.

If a back-up section contains more than 10 % of the sample, discard the sample as unreliable.

7.3 Determination of desorption efficiency

The desorption efficiencies (D) of VOCs can vary with the type and batch of sorbent used. Thus it is necessary for

each type of sorbent and for each analyte to determine D over the sample concentration range. Samples are

prepared as described in 4.6 and analysed as described in 7.2. Prepare at least three samples at each load level.

...

SLOVENSKI STANDARD
SIST ISO 16200-2:2002
01-maj-2002
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Workplace air quality - Sampling and analysis of volatile organic compounds by solvent

desorption/gas chromatography - Part 2: Diffusive sampling method
Qualité de l'air des lieux de travail - Échantillonnage et analyse des composés
organiques volatils par désorption au solvant/chromatographie en phase gazeuse -
Partie 2: Méthode d'échantillonnage par diffusion
Ta slovenski standard je istoveten z: ISO 16200-2:2000
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
SIST ISO 16200-2:2002 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 16200-2:2002
---------------------- Page: 2 ----------------------
SIST ISO 16200-2:2002
INTERNATIONAL ISO
STANDARD 16200-2
First edition
2000-06-15
Workplace air quality — Sampling and
analysis of volatile organic compounds
by solvent desorption/gas
chromatography —
Part 2:
Diffusive sampling method
Qualité de l'air des lieux de travail — Échantillonnage et analyse des
composés organiques volatils par désorption au solvant/chromatographie
en phase gazeuse —
Partie 2: Méthode d'échantillonnage par diffusion
Reference number
ISO 16200-2:2000(E)
ISO 2000
---------------------- Page: 3 ----------------------
SIST ISO 16200-2:2002
ISO 16200-2:2000(E)
PDF disclaimer

This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not

be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this

file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this

area.
Adobe is a trademark of Adobe Systems Incorporated.

Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters

were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event

that a problem relating to it is found, please inform the Central Secretariat at the address given below.

© ISO 2000

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SIST ISO 16200-2:2002
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Contents Page

1 Scope ..............................................................................................................................................................1

2 Normative references ....................................................................................................................................1

3 Principle..........................................................................................................................................................1

4 Reagents and materials ................................................................................................................................2

5 Apparatus .......................................................................................................................................................4

6 Sampling.........................................................................................................................................................5

7 Procedure .......................................................................................................................................................6

7.1 Desorption......................................................................................................................................................6

7.2 Analysis ..........................................................................................................................................................6

7.3 Determination of desorption efficiency.......................................................................................................6

7.4 Calibration of uptake rate .............................................................................................................................7

8 Calculations....................................................................................................................................................8

8.1 General............................................................................................................................................................8

8.2 Mass concentration of analyte .....................................................................................................................8

8.3 Volume concentration of analyte .................................................................................................................9

8.4 Uptake rates ...................................................................................................................................................9

9 Interferences ..................................................................................................................................................9

10 Precision and bias .........................................................................................................................................9

11 Storage and transport .................................................................................................................................10

12 Test report ....................................................................................................................................................10

13 Quality control..............................................................................................................................................10

Annex A (informative) Description of sorbent types .............................................................................................11

Annex B (informative) Diffusive sampling rates (cm /min)....................................................................................12

Annex C (informative) Equivalence of gas chromatographic stationary phases ...............................................20

Annex D (informative) Suppliers of charcoal-based organic vapour diffusive samplers..................................21

Annex E (informative) Specific information on sampler type A ...........................................................................22

Annex F (informative) Specific information on sampler type B ...........................................................................23

Annex G (informative) Specific information on sampler type C...........................................................................24

Annex H (informative) Specific information on sampler type D ...........................................................................25

Annex I (informative) Specific information on sampler type E.............................................................................26

Annex J (informative) Retention indices of selected VOCS on BP-1 and BP-10 phases...................................27

Bibliography..............................................................................................................................................................31

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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 3.

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 part of ISO 16200 may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

International Standard ISO 16200-2 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee

SC 2, Workplace atmospheres.

ISO 16200 consists of the following parts, under the general title Workplace air quality — Sampling and analysis of

volatile organic compounds by solvent desorption/gas chromatography:
� Part 1: Pumped sampling method
� Part 2: Diffusive sampling method
Annexes A to J of this part of ISO 16200 are for information only.
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SIST ISO 16200-2:2002
INTERNATIONAL STANDARD ISO 16200-2:2000(E)
Workplace air quality — Sampling and analysis of volatile organic
compounds by solvent desorption/gas chromatography —
Part 2:
Diffusive sampling method
1 Scope

This part of ISO 16200 gives general guidance for the sampling and analysis of volatile organic compounds (VOCs)

in air.

This part of ISO 16200 is applicable to a wide range of VOCs, including hydrocarbons, halogenated hydrocarbons,

esters, glycol ethers, ketones and alcohols. A number of devices and sorbents are recommended for the sampling

of these VOCs, each sorbent having a different range of applicability.

NOTE Activated coconut shell charcoal is frequently used. Very polar compounds may require derivatization; very low

boiling compounds will only be partially retained by the sorbents and can only be estimated qualitatively. Semi-volatile

compounds will be fully retained by the sorbents, but may only be partially recovered.

This part of ISO 16200 is valid for the measurement of airborne vapours of VOCs in a concentration range of

3 3

approximately 1 mg/m to 1000 mg/m individual organic for an exposure time of 8 h.

The upper limit of the useful range is set by the sorptive capacity of the sorbent used and, subject to dilution of the

analysed solution, 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 sampling devices or in the

desorption solvent. Artefacts are typically sub-nanogram for activated charcoal, but higher levels of aromatic

hydrocarbons have been noted in some batches.
2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of

this part of ISO 16200. For dated references, subsequent amendments to, or revisions of, any of these publications

do not apply. However, parties to agreements based on this part of ISO 16200 are encouraged to investigate the

possibility of applying the most recent editions of the normative documents indicated below. For undated

references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain

registers of currently valid International Standards.

EN 838:1995, Workplace atmospheres — Diffusive samplers for the determination of gases and vapours —

Requirements and test methods.
EN 1540, Workplace atmospheres — Terminology.
3Principle

Diffusive samplers consist of a sorbent separated from ambient air by some form of diffusion resistance, commonly

a controlled air gap and draught shield. The diffusive sampler (or samplers) is exposed to air for a measured time

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period. The rate of sampling is determined by prior calibration in a standard atmosphere (see 7.4). Volatile organic

compounds migrate into the sampler by diffusion and are collected on the sorbent, normally activated carbon. The

collected vapour is desorbed by a solvent, typically carbon disulfide, and the solution is analysed with a gas

chromatograph equipped with a flame ionization detector, mass spectrometer or other selective detector.

4 Reagents and materials
During the analysis, use only reagents of recognized analytical reagent grade.
4.1 Volatile organic compounds
A wide range of VOCs are required as reagents for calibration purposes.
4.2 Desorption solvent

The desorption solvent, commonly carbon disulfide, should be of chromatographic quality. It shall be free from

compounds co-eluting with the substances of interest. Check the purity of each new batch of solvent.

NOTE Carbon disulfide is normally recommended for the desorption of non-polar compounds from activated carbon. For

polar compounds and mixtures of polar and non-polar compounds, there is no ideal universal desorption solvent.

Dichloromethane, methanol, higher alcohols, dimethylformamide and acetonitrile have been used as eluants, either singly or

mixed with each other or carbon disulfide. Dichloromethane may cause corrosion in the flame ionization detector.

The use of carbon disulfide desorption solvent can result in problems when polar analytes are collected from humid

atmospheres. Polar analytes may be soluble in a water phase which forms following desorption with carbon

disulfide when sufficient water is collected with the sample. A desorption solvent modifier shall be present at a

sufficient concentration to result in a homogeneous solution in desorbed samples; dimethylformamide may be

suitable for this purpose.
4.3 Sorbents
4.3.1 Activated charcoal

A particle size of 0,35 mm to 0,85 mm is recommended. Before packing the samplers, the charcoal shall be heated

in an inert atmosphere, e.g. high-purity nitrogen, at approximately 600 °C for 1 h. To prevent recontamination of the

charcoal, it shall be kept in a clean atmosphere during cooling to room temperature, storage and loading into the

samplers. Samplers prepacked by the manufacturer with pre-conditioned charcoal are also available and require

no further conditioning.

NOTE 1 Activated charcoal is usually processed from coconut shells. Some manufacturers recommend synthetic carbons as

alternatives to charcoal of biological origin (see annexes A and B).

NOTE 2 The sorptive capacity and desorption efficiency of different batches of activated charcoal may vary. Commercial

samplers, if used, should be purchased from the same batch and in sufficient number to provide consistent performance for a

definite period of time.
4.3.2 Other sorbents
Sorbents other than charcoal may be used for certain applications (see annex B).

NOTE A description of sorbent types is given in annex A. Equivalent sorbents may be used.

4.4 Calibration standards
4.4.1 General

Calibration blend solutions are required in order to compare the concentrations of desorbed solutions (7.2) with

those calibration standards in the gas chromatographic analysis. Such solutions should be prepared in a way that

is traceable to national standards.
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An internal standard, for example trifluorotoluene or 3-bromofluorobenzene, is optional. If used, it should not

interfere with the compounds of interest and it should not be removed from the elution solvent by the sorbent. In the

context of this method, the purpose of the internal standard is to correct for small variations in the injection volume.

The use of an internal standard as a surrogate to correct for desorption efficiency (e.g. n-propyl acetate in the

analysis of n-butyl acetate) is not recommended. Desorption efficiency should be determined directly with the

compounds of interest (7.3).

Storage times for calibration solutions vary according to application. Typically, carbon disulfide dilutions should be

prepared fresh weekly, or more frequently if evidence is noted of decomposition or evaporation.

NOTE In the analysis of complex mixtures, calibration blends of the pure compounds may be prepared before dilution with

the elution solvent. Examples of three calibration blends are listed here. These have been used in the analysis of mixed

solvents in paints, thinners, adhesives, cleaning fluids and miscellaneous commercial products. The components are arranged

to give resolved peaks on both BP-1 and BP-10 phases . Other blends may be more appropriate on different columns or in

other applications.

a) Blend 1 consists of: n-hexane, n-heptane, n-octane, n-decane, n-undecane, n-dodecane, benzene, toluene, o-xylene, p-

xylene, n-propylbenzene, isopropylbenzene, o-ethyltoluene, m-ethyltoluene, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,3,5-

trimethylbenzene, n-propyl acetate, n-butyl acetate, isobutyl acetate, butoxyethyl acetate.

b) Blend 2 consists of: isopropanol, isobutanol, n-butanol, 1-methoxy-2-propanol, butoxyethanol, toluene, ethylbenzene,

1,2,3-trimethylbenzene, ethyl acetate, ethoxyethyl acetate.

c) Blend 3 consists of: acetone, 2-butanone, 4-methylpentan-2-one, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclo-

hexanone, 4-methylcyclohexanone, isopropyl acetate, n-nonane, toluene.

In the above examples, calibration blends 1-3 are stable for at least one year when stored in dark glass bottles with

polytetrafluoroethylene (PTFE)-lined screw-caps at less than 4 °C.
4.4.2 Solution containing approximately 10 mg/ml of each liquid component

Weigh 1 g of the substance or substances of interest into a 100 ml volumetric flask, starting with the least volatile

substance. Make up to 100 ml with desorption solvent (4.2), stopper and shake to mix.

4.4.3 Solution containing approximately 1 mg/ml of liquid components

Introduce 50 ml of desorption solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.4.2. Make up to 100 ml

with desorption solvent, stopper and shake to mix.
4.4.4 Solution containing approximately 100����g/ml of each liquid component.

Weigh 10 mg of the substance or substances of interest into a 100 ml volumetric flask, starting with the least

volatile substance. Make up to 100 ml with desorption solvent (4.2), stopper and shake to mix.

4.4.5 Solution containing approximately 10����g/ml of liquid components

Introduce 50 ml of desorption solvent into a 100 ml volumetric flask. Add 10 ml of solution 4.4.4. Make up to 100 ml

with desorption solvent, stopper and shake to mix.
4.4.6 Solution containing approximately 1 mg/ml of gas components

For gases, e.g. ethylene oxide, a high 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 precision 1 ml gas-tight syringe

BP-1 and BP-10 are examples of suitable products available commercially. This information is given for the convenience of

users of this part of ISO 16200 and does not constitute endorsement by ISO of these product. Equivalent products may be used

if they can be shown to lead to the same results. Annex C gives a non-exclusive list of products that are believed to be

equivalent.
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(5.5) with 1 ml of the pure gas and close the valve of the syringe. Using a septum vial of suitable capacity, add 2 ml

desorption solvent and close with the septum cap. Insert the tip of the syringe needle through the septum cap into

the desorption solvent. Open the valve and withdraw the plunger slightly to allow the desorption solvent to enter the

syringe. The action of the gas dissolving in the desorption 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 l.

4.4.7 Solution containing approximately 10��g/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 precision 10 �l gas-tight syringe

(5.5) with 10 �l of the pure gas and close the valve of the syringe. Using a septum vial of suitable capacity, add

2 ml desorption solvent and close with the septum cap. Insert the tip of the syringe needle through the septum cap

into the desorption solvent. Open the valve and withdraw the plunger slightly to allow the desorption solvent to

enter the syringe. The action of the gas dissolving in the desorption 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 l.

4.5 Calibration blend atmospheres (for 4.6 and 7.4)

Prepare standard atmospheres of known concentrations of the compound(s) of interest by a recognized method.

See for example ISO 6141, ISO 6145 and ISO 6349 [1-3]. If the procedure is not applied under conditions that will

allow the establishment of full traceability of the generated concentrations to primary standards, confirm the

delivered concentrations using an independent procedure .
4.6 Standards for desorption efficiency (for 7.3)

Prepare standards by exposure of the samplers to the standard atmosphere (4.5) for an accurately known time.

After exposure, remove and seal the samplers.

If the generation of standard atmospheres is not practicable, the standards may be prepared by a liquid spiking

procedure, provided that the accuracy of the spiking technique is established by using procedures giving spiking

levels traceable to primary standards of mass and/or volume, or is confirmed by an independent procedure. This is

the procedure usually recommended by manufacturers; follow the manufacturer’s guidance for specific instructions.

These will vary significantly with the sampler type, and some examples are given in annexes E to J. In principle,

load the devices by injecting aliquots of standard solutions (4.4) of accurately known mass or volume at three or

more levels onto clean samplers, seal the samplers and leave to equilibrate.
5 Apparatus
Ordinary laboratory apparatus and the following.
5.1 Diffusive samplers.

A number of solvent-desorption diffusive samplers are available commercially. Information on available devices is

given in annex D and information of available sorbent types in given in annex A. Manufacturer-supplied data on the

characteristics of some typical sampler types are given in annexes E to J.

NOTE Self-packed samplers should not be used unless they can be shown to have reproducible and constant sampling

rates.

The desorption efficiency (D) for each batch of samplers shall be checked by one of the methods described in 4.6

and 7.3.

Some diffusive samplers have a back-up section, which can be used as a check on overload of the sampling

section.
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5.2 Gas chromatograph, fitted with a flame ionization (FID), 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

5:1.
NOTE Dichloromethane may cause corrosion in the FID of some instruments.

The gas chromatograph column shall be capable of separating the analytes of interest from other components.

Examples of suitable choices are 50 m x 0,22 mm fused silica columns with BP-1 or BP-10 stationary phases. A

typical film thickness is in the range 0,5�mto 2,0�m. Typical operating conditions for these columns might be

temperature programming from 50 °C to 200 °C at 5 °C/min with a carrier gas flowrate of 0,7 ml/min to 0,8 ml/min

helium. Annex C gives a list of equivalent phases.
5.3 Autosampler.

Autosamplers are commercially available with liquid-chilled sample trays, suitable for the analysis of volatile

solvents.
5.4 Volumetric glassware.

Precision volumetric flasks of an accurately known volume, to be used for the preparation of calibration blend

solutions (4.4). These should be obtained from suppliers issuing certificates of calibration traceable to primary

standards or be traceably calibrated in the laboratory by weighing of the solvent(s) applied.

5.5 Syringes (for 4.4.6 and 4.4.7).

Precision gas-tight syringes of accurately known volumes of 1,0 ml and 10�l, readable to 0,01 ml and 0,1�l

respectively.
6 Sampling

Select a diffusive sampler appropriate for the compound or mixture to be sampled. Guidance on the availability of

suitable samplers is given in 5.1. Annex B gives information on the availability of manufacturer-supplied diffusive

uptake rates for a range of VOCs and, where appropriate, any special conditions, e.g. a variation from the basic

device design. If a device is not listed for a particular VOC, it will be necessary to calibrate the device according to

7.4.

Follow the manufacturer’s guidance for specific sampling instructions. These will vary significantly with the sampler

type, and some examples are given in annexes E to J. In principle, any protective cover is removed before the

diffusive sampler is exposed to the target atmosphere, and the sampler is re-sealed again at the end.

When intended for personal sampling, mount the sampler in the breathing zone as defined in accordance with

EN 1540. When used for fixed-location sampling, choose a suitable sampling site. In either case, the sampler

should have unrestricted access to the sampled atmosphere, i.e. it should not be obscured by the wearer’s clothing

or other objects.

NOTE Some designs of diffusive sampler are affected by air velocity. See 7.4 for details.

The exposure time recommended for the VOCs covered by this part of ISO 16200 is normally 8 h for workplace

monitoring. If the maximum exposure time recommended is less than 8 h, this is indicated in annex B. Sampling

over shorter periods is possible, down to 30 min for workplace monitoring, but the limits of the measurable

concentration range increase accordingly. For example, for a 4-h sampling period, the concentration range is

3 3
approximately 2 mg/m to 2 000 mg/m .

Samplers should be uniquely labelled. Solvent-containing paints and markers or adhesive labels should not be

used to label the samplers.

Record air temperature and barometric pressure periodically during sampling if it is desired either to express

concentrations reduced to specific conditions (8.2) or to express concentrations as volume fractions (8.3).

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Field blanks should be prepared by using samplers identical to those used for sampling and subjecting them to the

same handling procedure as the samples except for the actual period of sampling. Label these as blanks.

7 Procedure

CAUTION — This part of ISO 16200 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 16200 to establish appropriate

health and safety practices and determine the applicability of regulatory limitations prior to use.

7.1 Desorption

If samples are not to be analysed within 8 h, they shall be placed in a clean, uncoated, sealed metal or glass

container.

In each case, carry out the desorption in a clean atmosphere in a fume hood. Desorb the sample blanks in the

same way as the samples.

Follow the manufacturer’s guidance for specific desorption instructions. These will vary significantly with the

sampler type, and some examples are given in annexes D to H. In principle, the collected VOC is extracted from

the sorbent (4.3) with a suitable solvent (4.2). In some cases, the desorption is done without disassembling the

device; in others, the sorbent is removed and desorbed in a separate vessel.
If there is a back-up section of sorbent, this should be desorbed separately.

NOTE In some circumstances, a higher D may be obtained with ultrasonic extraction as opposed to mechanical shaking.

7.2 Analysis

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 (see 5.2). The choice will depend largely on which

compounds, if any, are present that might interfere in the chromatographic analysis.

Inject a known fixed volume (1 μl to 5 μl) of each standard solution (4.4) into the gas chromatograph. A

standardized injection technique should be used so that repeatable peak heights or areas are obtained. Typically,

for a series of replicate injections, the relative stand
...

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