ISO 17736:2010

INTERNATIONAL ISO
STANDARD 17736
First edition
2010-12-15
Workplace air quality — Determination of
isocyanate in air using a double-filter
sampling device and analysis by high
pressure liquid chromatography
Qualité de l'air des lieux de travail — Dosage des isocyanates dans l'air
au moyen d'un dispositif d'échantillonnage à filtre double et par analyse
par chromatographie liquide à haute performance

Reference number
©
ISO 2010
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ii © ISO 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Principle.1
4 Reagents and materials .2
5 Apparatus.3
6 Air sampling.4
6.1 Calibration of sampling system .4
6.2 Preparation of sampling equipment.4
6.3 Preparation of MAMA-impregnated filter .4
6.4 Collection of samples .4
6.5 Blanks.5
7 Procedure.5
7.1 Safety precautions .5
7.2 Calibration standard.5
8 Sample processing.6
8.1 Vapour analysis .6
8.2 Aerosol analysis .6
9 HPLC conditions.7
9.1 General .7
9.2 HPLC conditions — vapour isocyanates .7
9.3 HPLC conditions — aerosol isocyanates .7
10 Analysis.8
10.1 Calibration curve .8
10.2 Quality control .8
10.3 Sample quantification .8
11 Interference .9
12 Determination of performance characteristics .10
12.1 Introduction.10
12.2 Relevant uncertainty contributions and criteria .10
12.3 Assessment of performance characteristics, following the detailed approach in
[5]
ISO/IEC Guide 98-3 .11
Annex A (informative) Performance characteristics .18
Annex B (informative) Sample chromatograms.20
Bibliography.27

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 17736 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace
atmospheres.
iv © ISO 2010 – All rights reserved

Introduction
Isocyanates are commercially available chemicals used in the polyurethane industry. They are known to
cause health problems, such as asthma, contact dermatitis and hypersensitivity pneumonitis, in workers even
at very low levels in occupational environments.
Since isocyanates are highly reactive compounds and exposure limits are very low, the sampling and the
analysis of these substances are critical.
This method is based on the standard method developed by the Institut de Recherche en Santé et en Sécurité
du Travail [Occupational Health and Safety Research Institute] (IRSST) of Quebec. It has been in use for
more than 18 years as the standard government method in that province of Canada. Since 1996, it has been
introduced into the marketplace in the USA, Brazil, and the UK. After a year’s study (Reference [10]), the
method was adopted in 1998-11 by the US Air Force as an acceptable alternative to NIOSH Method 5521 for
monomeric isocyanates (now withdrawn).
The method is now routinely used in the Canadian provinces of Alberta, British Columbia, and Ontario, and in
the US state of Washington, which has validated the method for TDI. Thirteen laboratories have been
schooled in this analytical method, three in Canada, eight in the USA and Mexico, one in Brazil, and one in the
UK. This method has been in use in several countries for many years and 13 laboratories participate in round
robin testing on a regular basis in order to maintain their proficiency.
The double-filter method has been validated for different applications of isocyanates such as spray-painting
(Reference [11]) and foam manufacturing. It has also been compared with other established methods and
demonstrated equivalent results (Reference [10]).
[7] [8] [9]
Double-filter methods are also available in ASTM D6561 and ASTM D6562 for HDI, and ASTM D5932
for TDI.
ISO draws attention to the fact that it is claimed that compliance with this document may involve the use of a
patent concerning the double-filter sampling device for isocyanates.
INTERNATIONAL STANDARD ISO 17736:2010(E)

Workplace air quality — Determination of isocyanate in air
using a double-filter sampling device and analysis by high
pressure liquid chromatography
1 Scope
This International Standard gives general guidelines for the sampling and analysis of airborne isocyanates in
workplace air. This International Standard is appropriate for organic compounds containing free isocyanate
functional groups and is specific for the quantification of monomers, polymers and prepolymers, vapours and
aerosols. Differential air sampling is performed with a segregating device which can show the physical state of
the isocyanates analysed as found in the field. This capacity, however, may show limitations for given
situations, e.g. when aerosols collected on the first filter contain free monomer that migrates to the second
filter and is then quantified as vapour phase isocyanate. The determination of aromatic monomers includes
toluene diisocyanate (TDI) and 4,4'-diisocyanato-diphenylmethane (MDI). Aliphatic monomers include
isophorone diisocyanate (IPDI), 4,4'-methylene bis-(cyclohexyl isocyanate) (HMDI) and 1,6-hexamethylene
diisocyanate (HDI). Isocyanate oligomers and prepolymers can also be determined using this method.
The double-filter method is designed to determine short-term (15 min) exposure concentrations of organic
isocyanates in a workplace environment by personal monitoring or by fixed location monitoring. However, if
the exposure is expected to be in vapour form only, then sampling time can be extended to 8 h. Since the filter
is derivatized in the field immediately after sampling, loss of isocyanate aerosol because of its reaction with
other chemicals is negligible except for very fast-reacting isocyanate systems such as foam spraying of MDI in
polyurethane applications. The method is suitable for the measurement of airborne organic isocyanates in the
NCO equivalent concentration range of 0,01 µg/sample to 2,1 µg/sample, corresponding to approximately
3 3
0,67 µg/m to 140 µg/m for a 15 l sample volume. This range brackets about eight times the current
established threshold limit value (TLV) of 5 ppb for monomers set by many national authorities.
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 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
EN 1232, Workplace atmospheres — Pumps for personal sampling of chemical agents — Requirements and
test methods
3 Principle
A measured volume of air is drawn through a double-filter sampling device in which the first filter made of
polytetrafluoroethylene (PTFE) collects the aerosols and then the isocyanate vapour is absorbed on a glass
fibre (GF) filter impregnated with 9-(methylaminomethyl)anthracene (MAMA). The isocyanate present as an
aerosol is collected on the PTFE filter and derivatized immediately after sampling, in a 5 ml solution of
1-(2-methoxyphenyl)piperazine (MP), 0,1 mg/ml in toluene.
Both isocyanate monomer and oligomer urea derivatives solutions are separated using reversed phase high
performance liquid chromatography (HPLC). Vapour monomers are analysed by HPLC using an
ultraviolet (UV) and fluorescence (FL) detector. Fluo
...