Workplace atmospheres — Determination of total isocyanate groups in air using 1-(9-anthracenylmethyl)piperazine (MAP) reagent and liquid chromatography

This document specifies a method for the sampling and analysis of airborne organic isocyanates in workplace air. This document is applicable to a wide range of organic compounds containing isocyanate groups, including monofunctional isocyanates (e.g. phenyl isocyanate), diisocyanate monomers [e.g. 1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), and isophorone diisocyanate (IPDI)], prepolymers (e.g. the biuret and isocyanurate of HDI), as well as chromatographable intermediate products formed during production or thermal breakdown of polyurethane. In mixed systems of HDI and IPDI products, it is impossible to identify and quantify low levels of IPDI monomer using this document, due to coelution of IPDI monomer with HDI-uretidinedione. It is known that the method underestimates the oligomer in MDI-based products. Total isocyanate group (NCO) is underestimated in MDI-based products by about 35 % as compared to dibutylamine titration. The method has been successfully modified to be used with LC-MS-MS for TDI monomer using an isocratic 70 % acetonitrile/30 % 10 mM ammonium formate mobile phase. The useful range of the method, expressed in moles of isocyanate group per species per sample, is approximately 1 × 10−10 to 2 × 10−7. The instrumental detection limit for the monomers using both ultraviolet (UV) detection and fluorescence (FL) detection is about 2 ng monomer per sample. The useful limit of detection for the method using reagent impregnated filters is about 10 ng to 20 ng monomer per sample for both UV and FL detection. For a 15 l sample, this corresponds to 0,7 µg/m−3 to 1,4 µg/m−3. For impinger samples, which require solid phase extraction, experience has shown that the useful limit of detection is about 30 ng to 80 ng monomer per sample.

Air des lieux de travail — Dosage des groupements isocyanates totaux dans l'air par réaction avec la 1-(9-anthracénylméthyl)pipérazine (MAP) et par chromatographie en phase liquide

Zrak na delovnem mestu - Določevanje skupin izocianatov v zraku z reagentom 1-(9-antracenilmetil)piperazin (MAP) in s tekočinsko kromatografijo

Ta dokument določa metodo za vzorčenje in analizo organskih izocianatnih spojin v
zraku na delovnem mestu.
Ta dokument se uporablja za širok nabor organskih spojin, ki vsebujejo skupine izocianatov, vključno z monofunkcijskimi izocianati (npr. fenil izocianat), monomeri diizocianata [npr.
1,6-heksametilen diizocianat (HDI), toluen diizocianat (TDI), difenilmetan-4,4’-diizocianat (MDI) in izoforon diizocianat (IPDI)], prepolimeri (npr. biuret in izocianurat HDI) ter za vmesne proizvode, ki so primerni za kromatografijo in oblikovani med proizvodnjo ali toplotno razgradnjo poliuretana.
V mešanih sistemih izdelkov HDI in IPDI je mogoče s tem dokumentom določiti in količinsko opredeliti nizke ravni monomera IPDI zaradi koelucije monomera IPDI z uretidindionom HDI. Znano je, da metoda podcenjuje oligomer v izdelkih iz MDI. Celotna skupina izocianatov (NCO) je v izdelkih iz MDI podcenjena za približno 35 % v primerjavi s titracijo
dibutilamina.
Metoda je bila uspešno prilagojena za določevanje monomera TDI z uporabo tekočinske kromatografije s tandemsko masno spektrometrijo (LC-MS-MS) pri
izokratski mobilni fazi, sestavljeni iz 70 % acetonitrila in 30 % amonijevega formata 10 mM.
Uporabno območje metode, izraženo v molih skupine izocianatov na zvrst na vzorec, je
približno 1 × 10−10 do 2 × 10−7. Meja detekcije instrumentov za monomere je pri
ultravijoličnem (UV) in fluorescentnem (FL) zaznavanju v obeh primerih približno 2 ng monomera na vzorec. Uporabna
meja zaznavanja za metodo z uporabo filtrov, prepojenih z reagenti, je približno od 10 ng do 20 ng monomera na vzorec za UV- in FL-zaznavanje. Pri 15-litrskem vzorcu to ustreza od 0,7 μg/m−3 do 1,4 μg/m−3. Pri vzorcih za kinetični vzorčevalnik, za katerega je potrebna ekstrakcija v trdni fazi, izkušnje kažejo, da je uporabna meja zaznavanja od približno 30 ng do 80 ng monomera na vzorec.

General Information

Status
Published
Publication Date
31-Mar-2019
Current Stage
6060 - International Standard published
Start Date
01-Apr-2019
Completion Date
01-Apr-2019

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INTERNATIONAL ISO
STANDARD 17735
Second edition
2019-04
Workplace atmospheres —
Determination of total
isocyanate groups in air using
1-(9-anthracenylmethyl)piperazine
(MAP) reagent and liquid
chromatography
Air des lieux de travail — Dosage des groupements isocyanates totaux
dans l'air par réaction avec la 1-(9-anthracénylméthyl)pipérazine
(MAP) et par chromatographie en phase liquide
Reference number
ISO 17735:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 17735:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 17735:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Reagents and materials ................................................................................................................................................................................. 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 MAP reagent .............................................................................................................................................................................................. 4

5.3 Reagent solutions ................................................................................................................................................................................. 5

5.3.1 Impinger solution ...................................................................... ...................................................................................... 5

5.3.2 Solution for filter impregnation .......................................................................................................................... 6

5.3.3 Filter extraction solution .......................................................................................................................................... 6

5.3.4 Stability of reagent solutions ................................................................................................................................ 6

5.4 Standard matching solutions ...................................................................................................................................................... 6

5.4.1 General...................................................................................................................................................................................... 6

5.4.2 Preparation of monomer derivatives ............................................................................................................. 7

5.4.3 Preparation of standard solutions of monomer derivatives for HPLC analysis ........ 7

5.4.4 Preparation of monomer derivatives for solid-phase extraction (SPE) ........................... 7

5.4.5 Preparation of derivative solutions of bulk isocyanate products .......................................... 8

5.5 HPLC mobile phase.............................................................................................................................................................................. 8

5.5.1 General...................................................................................................................................................................................... 8

5.5.2 Mobile phase buffer solutions .............................................................................................................................. 8

5.5.3 Primary mobile phases ........................................................................................................................................... .... 8

5.5.4 Post-column acid mobile phase .......................................................................................................................... 9

6 Apparatus ..................................................................................................................................................................................................................... 9

6.1 General ........................................................................................................................................................................................................... 9

6.2 Sampler .......................................................................................................................................................................................................... 9

6.2.1 General...................................................................................................................................................................................... 9

6.2.2 Filters ......................................................................................................................................................................................... 9

6.2.3 Midget impingers ............................................................................................................................................................ 9

6.3 Sampling pump ....................................................................................................................................................................................10

6.4 Tubing ..........................................................................................................................................................................................................10

6.5 Flowmeter ................................................................................................................................................................................................10

6.6 Filtration and solid-phase extraction equipment ..................................................................................................10

6.7 Liquid chromatographic system ...........................................................................................................................................10

6.7.1 Autosampler .....................................................................................................................................................................10

6.7.2 Pumping system ............................................................................................................................................................10

6.7.3 Analytical column .........................................................................................................................................................10

6.7.4 Column oven .....................................................................................................................................................................11

6.7.5 Post-column acid delivery pump ....................................................................................................................11

6.7.6 Detectors ..............................................................................................................................................................................11

7 Air sampling ...........................................................................................................................................................................................................11

7.1 Pre-sampling laboratory preparation ..............................................................................................................................11

7.1.1 Cleaning of sampling equipment ....................................................................................................................11

7.1.2 Preparation of MAP-coated filter samplers ...........................................................................................11

7.1.3 Preparation of extraction solution jars......................................................................................................11

7.2 Pre-sampling field preparation ..............................................................................................................................................11

7.2.1 Calibration of pump ...................................................................................................................................................11

7.2.2 Preparation of samplers .........................................................................................................................................12

7.3 Collection of air samples .............................................................................................................................................................12

7.3.1 Filter sampling ................................................................................................................................................................12

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 17735:2019(E)

7.3.2 Impinger sampling ......................................................................................................................................................12

7.3.3 Sampling with an impinger followed by a filter .................................................................................12

7.4 Blanks and negative controls ...................................................................................................................................................12

7.5 Bulk products ........................................................................................................................................................................................13

7.6 Shipment of samples .......................................................................................................................................................................13

7.7 Filter test samples .............................................................................................................................................................................13

7.8 Impinger test samples ...................................................................................................................................................................13

8 HPLC analysis ........................................................................................................................................................................................................14

8.1 Instrumental settings .....................................................................................................................................................................14

8.2 HPLC programme...............................................................................................................................................................................14

9 Data handling ........................................................................................................................................................................................................15

9.1 Monomer measurement ..............................................................................................................................................................15

9.2 Oligomer measurement (total detectable isocyanate) ......................................................................................16

10 Calibration and quality control ..........................................................................................................................................................16

10.1 Standard matching solutions ...................................................................................................................................................16

10.2 Calibration curves .............................................................................................................................................................................16

10.3 Blank tests ................................................................................................................................................................................................17

10.4 Bulk products ........................................................................................................................................................................................17

10.5 Quality control spikes ....................................................................................................................................................................17

11 Calculations.............................................................................................................................................................................................................17

11.1 Monomer ...................................................................................................................................................................................................17

11.2 Oligomers (total detectable isocyanate) ........................................................................................................................18

12 Interferences .........................................................................................................................................................................................................18

13 Determination of performance characteristics.................................................................................................................19

13.1 General ........................................................................................................................................................................................................19

13.2 Assessment of performance characteristics ...............................................................................................................20

13.2.1 Collection efficiency relative to particle size distribution.........................................................20

13.2.2 Air sampling ......................................................................................................................................................................20

13.2.3 Analysis .................................................................................................................................................................................21

13.2.4 Mass of compound in sample blank .............................................................................................................25

13.2.5 Between-laboratory uncertainty contributions ................................................................................26

13.2.6 Combined uncertainty .............................................................................................................................................26

13.2.7 Expanded uncertainty ..............................................................................................................................................26

13.2.8 Uncertainty from performance criteria ....................................................................................................26

Annex A (informative) Performance characteristics ........................................................................................................................27

Bibliography .............................................................................................................................................................................................................................29

iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 17735:2019(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2,

Workplace atmospheres.

This second edition cancels and replaces the first edition (ISO 17735:2009), which has been technically

revised. The main changes compared to the previous edition are as follows.
— Additional limit of detection information has been provided (Clause 1).

— The method has been used in high air concentrations successfully with a higher reagent concentration

in an impinger (5.3.1).

— During processing of impinger samples, rinsing the SPE cartridge with 6 ml dichloromethane has

been changed to rinsing with two consecutive 3 ml aliquots. This is more effective in removing all

of the butyl benzoate impinger solvent (7.8).

— The liquid chromatographic system has been adapted to use a smaller diameter analytical column

(6.7.3).

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
© ISO 2019 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 17735:2019(E)
Introduction

This document specifies the use of 1-(9-anthracenylmethyl)piperazine (MAP) to measure monomeric

and oligomeric isocyanate species in workplace atmospheres. MAP was designed to improve the

reliability of identification of isocyanate species in sample chromatograms and to improve the

accuracy of quantification of these species relative to established reagents. The high performance

liquid chromatography (HPLC) analysis uses a pH gradient to selectively accelerate the elution of

MAP derivatives of oligomeric isocyanates that might be unobservable in an isocratic analysis. The

[8]

performance of MAP has been compared to other reagents used for total isocyanate analysis , MAP has

been found to react with phenyl isocyanate (used as a model isocyanate) as fast as or faster than other

reagents commonly used for isocyanate analysis. The UV response of MAP derivatives is comparable

to that of 9-(methylaminomethyl)anthracene (MAMA) derivatives and considerably greater than other

commonly used reagents [approximately three times greater than 1-(2-methoxyphenyl)piperazine

(1-2MP) derivatives of aromatic isocyanates and 14 times greater than 1-2MP derivatives of aliphatic

isocyanates]. The compound-to-compound variability of UV response per isocyanate group for MAP

derivatives is smaller than the variability of any other commonly used reagent/detector combination

(the coefficient of variation is 3,5 % for five model isocyanates). This results in more accurate

quantification of detectable non-monomeric isocyanate species based on a calibration curve generated

from analysing standards of monomeric species. The monomeric species used for calibration is generally

the one associated with the product being analysed, but others could be used due to the very small

compound-to-compound response variability of the MAP derivatives. The intensity of fluorescence

response of MAP derivatives is comparable to that of MAMA derivatives and considerably greater

than other reagents (e.g. approximately 30 times more intense than that of tryptamine derivatives).

The compound-to-compound variability in fluorescence response has been found to be smaller than

that of MAMA derivatives but larger than that of tryptamine derivatives (MAMA = 59 % coefficient

of variation, MAP = 33 % coefficient of variation, and tryptamine = 16 % coefficient of variation for

5 model isocyanates). The compound-to-compound fluorescence variability of MAP derivatives is

considered too great for accurate quantification of non-monomeric isocyanate species based on

calibration with monomer standards. However, the sensitivity of the fluorescence detection makes

it especially suitable for quantification of low levels of monomer, and the selectivity is very useful to

designate an unidentified HPLC peak as a MAP derivative. MAP derivatives also give a strong response

by electrochemical detection. The pH gradient used in the HPLC analysis selectively accelerates the

elution of amines (MAP derivatives are amines) and is very strong (it accelerates MDI more than

100-fold). Re-equilibration to initial conditions is almost immediate. Many oligomeric species can be

measured in the 30 min MAP analysis that may be unobservable in a much longer isocratic analysis.

MAP has been used in several studies comparing it side-by-side with other methods. Reference [9]

found MAP impingers and NIOSH 5521 impingers (comparable to MDHS 25) to give comparable

results in spray painting environments. Reference [9] used MAP reagent, but the pH gradient was not

employed. Reference [10] compared MAP impingers with several other impinger methods (NIOSH 5521

and NIOSH 5522) and the double filter method. The average MAP oligomer value was substantially

higher than the other impinger methods and slightly higher than the double filter method. The pH

gradient was used in these MAP analyses. Reference [11] found that the MAP oligomer results compared

favourably against several other methods for measurement of oligomeric isocyanates in the collision

repair industry, and agreed well with the reference values.
[12]

The MAP method is currently available as NIOSH Method 5525 . The performance characteristics of

the method have been evaluated in Reference [13].
vi © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 17735:2019(E)
Workplace atmospheres — Determination of total
isocyanate groups in air using 1-(9-anthracenylmethyl)
piperazine (MAP) reagent and liquid chromatography
1 Scope

This document specifies a method for the sampling and analysis of airborne organic isocyanates in

workplace air.

This document is applicable to a wide range of organic compounds containing isocyanate groups,

including monofunctional isocyanates (e.g. phenyl isocyanate), diisocyanate monomers [e.g.

1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate

(MDI), and isophorone diisocyanate (IPDI)], prepolymers (e.g. the biuret and isocyanurate of HDI), as

well as chromatographable intermediate products formed during production or thermal breakdown of

polyurethane.

In mixed systems of HDI and IPDI products, it is impossible to identify and quantify low levels of IPDI

monomer using this document, due to coelution of IPDI monomer with HDI-uretidinedione.

It is known that the method underestimates the oligomer in MDI-based products. Total isocyanate

group (NCO) is underestimated in MDI-based products by about 35 % as compared to dibutylamine

titration.

The method has been successfully modified to be used with LC-MS-MS for TDI monomer using an

isocratic 70 % acetonitrile/30 % 10 mM ammonium formate mobile phase.

The useful range of the method, expressed in moles of isocyanate group per species per sample, is

−10 −7

approximately 1 × 10 to 2 × 10 . The instrumental detection limit for the monomers using both

ultraviolet (UV) detection and fluorescence (FL) detection is about 2 ng monomer per sample. The

useful limit of detection for the method using reagent impregnated filters is about 10 ng to 20 ng

monomer per sample for both UV and FL detection. For a 15 l sample, this corresponds to 0,7 µg/m to

1,4 µg/m . For impinger samples, which require solid phase extraction, experience has shown that the

useful limit of detection is about 30 ng to 80 ng monomer per sample.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

EN 1232, Workplace atmospheres — Pumps for personal sampling of chemical agents — Requirements and

test methods
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
© ISO 2019 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 17735:2019(E)
4 Principle

A measured volume of air is drawn through either an impinger containing a solution of

1-(9-anthracenylmethyl)piperazine (MAP), a filter impregnated with MAP, or a sampling train

consisting of an impinger followed by an impregnated filter. The choice of sampler depends on the

chemical and physical characteristics of the airborne isocyanate[14]. If an impinger is used, the

solution is subjected to solid-phase extraction (SPE) and the eluate is concentrated and analysed by

reverse phase high performance liquid chromatography (HPLC) with ultraviolet (UV) absorbance

and fluorescence (FL) detection in series. If an impregnated filter is used for sampling, it is extracted

with solvent either in the field after completion of sampling or in the laboratory. Waiting to extract

the filter until after the sample has been received by the analytical laboratory is acceptable only for

analysis of isocyanates collected as vapour. This solution is filtered and analysed by HPLC/UV/FL.

Isocyanate-derived peaks are identified based on their UV and FL responses and by comparison with

the chromatogram of a derivatized bulk isocyanate product if available. Quantification of compounds

for which analytical standards are available (generally monomers) is achieved by comparison of the FL

peak height of the sample peak with the FL peak height of standard matching solutions. Quantification

of compounds for which analytical standards are not available is achieved by comparison of the UV

area of the sample peak with the UV area of the appropriate monomer standard (i.e. the monomer from

which the isocyanate product is derived).
Structures of some common diisocyanate monomers are shown in Figure 1.
2 © ISO 2019 – All ri
...

SLOVENSKI STANDARD
SIST ISO 17735:2019
01-september-2019
Zrak na delovnem mestu - Določevanje skupin izocianatov v zraku z reagentom 1-
(9-antracenilmetil)piperazin (MAP) in s tekočinsko kromatografijo

Workplace atmospheres - Determination of total isocyanate groups in air using 1-(9-

anthracenylmethyl)piperazine (MAP) reagent and liquid chromatography

Air des lieux de travail - Dosage des groupements isocyanates totaux dans l'air par

réaction avec la 1-(9-anthracénylméthyl)pipérazine (MAP) et par chromatographie en

phase liquide
Ta slovenski standard je istoveten z: ISO 17735:2019
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
SIST ISO 17735:2019 en

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

---------------------- Page: 1 ----------------------
SIST ISO 17735:2019
---------------------- Page: 2 ----------------------
SIST ISO 17735:2019
INTERNATIONAL ISO
STANDARD 17735
Second edition
2019-04
Workplace atmospheres —
Determination of total
isocyanate groups in air using
1-(9-anthracenylmethyl)piperazine
(MAP) reagent and liquid
chromatography
Air des lieux de travail — Dosage des groupements isocyanates totaux
dans l'air par réaction avec la 1-(9-anthracénylméthyl)pipérazine
(MAP) et par chromatographie en phase liquide
Reference number
ISO 17735:2019(E)
ISO 2019
---------------------- Page: 3 ----------------------
SIST ISO 17735:2019
ISO 17735:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 17735:2019
ISO 17735:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Reagents and materials ................................................................................................................................................................................. 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 MAP reagent .............................................................................................................................................................................................. 4

5.3 Reagent solutions ................................................................................................................................................................................. 5

5.3.1 Impinger solution ...................................................................... ...................................................................................... 5

5.3.2 Solution for filter impregnation .......................................................................................................................... 6

5.3.3 Filter extraction solution .......................................................................................................................................... 6

5.3.4 Stability of reagent solutions ................................................................................................................................ 6

5.4 Standard matching solutions ...................................................................................................................................................... 6

5.4.1 General...................................................................................................................................................................................... 6

5.4.2 Preparation of monomer derivatives ............................................................................................................. 7

5.4.3 Preparation of standard solutions of monomer derivatives for HPLC analysis ........ 7

5.4.4 Preparation of monomer derivatives for solid-phase extraction (SPE) ........................... 7

5.4.5 Preparation of derivative solutions of bulk isocyanate products .......................................... 8

5.5 HPLC mobile phase.............................................................................................................................................................................. 8

5.5.1 General...................................................................................................................................................................................... 8

5.5.2 Mobile phase buffer solutions .............................................................................................................................. 8

5.5.3 Primary mobile phases ........................................................................................................................................... .... 8

5.5.4 Post-column acid mobile phase .......................................................................................................................... 9

6 Apparatus ..................................................................................................................................................................................................................... 9

6.1 General ........................................................................................................................................................................................................... 9

6.2 Sampler .......................................................................................................................................................................................................... 9

6.2.1 General...................................................................................................................................................................................... 9

6.2.2 Filters ......................................................................................................................................................................................... 9

6.2.3 Midget impingers ............................................................................................................................................................ 9

6.3 Sampling pump ....................................................................................................................................................................................10

6.4 Tubing ..........................................................................................................................................................................................................10

6.5 Flowmeter ................................................................................................................................................................................................10

6.6 Filtration and solid-phase extraction equipment ..................................................................................................10

6.7 Liquid chromatographic system ...........................................................................................................................................10

6.7.1 Autosampler .....................................................................................................................................................................10

6.7.2 Pumping system ............................................................................................................................................................10

6.7.3 Analytical column .........................................................................................................................................................10

6.7.4 Column oven .....................................................................................................................................................................11

6.7.5 Post-column acid delivery pump ....................................................................................................................11

6.7.6 Detectors ..............................................................................................................................................................................11

7 Air sampling ...........................................................................................................................................................................................................11

7.1 Pre-sampling laboratory preparation ..............................................................................................................................11

7.1.1 Cleaning of sampling equipment ....................................................................................................................11

7.1.2 Preparation of MAP-coated filter samplers ...........................................................................................11

7.1.3 Preparation of extraction solution jars......................................................................................................11

7.2 Pre-sampling field preparation ..............................................................................................................................................11

7.2.1 Calibration of pump ...................................................................................................................................................11

7.2.2 Preparation of samplers .........................................................................................................................................12

7.3 Collection of air samples .............................................................................................................................................................12

7.3.1 Filter sampling ................................................................................................................................................................12

© ISO 2019 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 17735:2019
ISO 17735:2019(E)

7.3.2 Impinger sampling ......................................................................................................................................................12

7.3.3 Sampling with an impinger followed by a filter .................................................................................12

7.4 Blanks and negative controls ...................................................................................................................................................12

7.5 Bulk products ........................................................................................................................................................................................13

7.6 Shipment of samples .......................................................................................................................................................................13

7.7 Filter test samples .............................................................................................................................................................................13

7.8 Impinger test samples ...................................................................................................................................................................13

8 HPLC analysis ........................................................................................................................................................................................................14

8.1 Instrumental settings .....................................................................................................................................................................14

8.2 HPLC programme...............................................................................................................................................................................14

9 Data handling ........................................................................................................................................................................................................15

9.1 Monomer measurement ..............................................................................................................................................................15

9.2 Oligomer measurement (total detectable isocyanate) ......................................................................................16

10 Calibration and quality control ..........................................................................................................................................................16

10.1 Standard matching solutions ...................................................................................................................................................16

10.2 Calibration curves .............................................................................................................................................................................16

10.3 Blank tests ................................................................................................................................................................................................17

10.4 Bulk products ........................................................................................................................................................................................17

10.5 Quality control spikes ....................................................................................................................................................................17

11 Calculations.............................................................................................................................................................................................................17

11.1 Monomer ...................................................................................................................................................................................................17

11.2 Oligomers (total detectable isocyanate) ........................................................................................................................18

12 Interferences .........................................................................................................................................................................................................18

13 Determination of performance characteristics.................................................................................................................19

13.1 General ........................................................................................................................................................................................................19

13.2 Assessment of performance characteristics ...............................................................................................................20

13.2.1 Collection efficiency relative to particle size distribution.........................................................20

13.2.2 Air sampling ......................................................................................................................................................................20

13.2.3 Analysis .................................................................................................................................................................................21

13.2.4 Mass of compound in sample blank .............................................................................................................25

13.2.5 Between-laboratory uncertainty contributions ................................................................................26

13.2.6 Combined uncertainty .............................................................................................................................................26

13.2.7 Expanded uncertainty ..............................................................................................................................................26

13.2.8 Uncertainty from performance criteria ....................................................................................................26

Annex A (informative) Performance characteristics ........................................................................................................................27

Bibliography .............................................................................................................................................................................................................................29

iv © ISO 2019 – All rights reserved
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SIST ISO 17735:2019
ISO 17735:2019(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2,

Workplace atmospheres.

This second edition cancels and replaces the first edition (ISO 17735:2009), which has been technically

revised. The main changes compared to the previous edition are as follows.
— Additional limit of detection information has been provided (Clause 1).

— The method has been used in high air concentrations successfully with a higher reagent concentration

in an impinger (5.3.1).

— During processing of impinger samples, rinsing the SPE cartridge with 6 ml dichloromethane has

been changed to rinsing with two consecutive 3 ml aliquots. This is more effective in removing all

of the butyl benzoate impinger solvent (7.8).

— The liquid chromatographic system has been adapted to use a smaller diameter analytical column

(6.7.3).

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
© ISO 2019 – All rights reserved v
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SIST ISO 17735:2019
ISO 17735:2019(E)
Introduction

This document specifies the use of 1-(9-anthracenylmethyl)piperazine (MAP) to measure monomeric

and oligomeric isocyanate species in workplace atmospheres. MAP was designed to improve the

reliability of identification of isocyanate species in sample chromatograms and to improve the

accuracy of quantification of these species relative to established reagents. The high performance

liquid chromatography (HPLC) analysis uses a pH gradient to selectively accelerate the elution of

MAP derivatives of oligomeric isocyanates that might be unobservable in an isocratic analysis. The

[8]

performance of MAP has been compared to other reagents used for total isocyanate analysis , MAP has

been found to react with phenyl isocyanate (used as a model isocyanate) as fast as or faster than other

reagents commonly used for isocyanate analysis. The UV response of MAP derivatives is comparable

to that of 9-(methylaminomethyl)anthracene (MAMA) derivatives and considerably greater than other

commonly used reagents [approximately three times greater than 1-(2-methoxyphenyl)piperazine

(1-2MP) derivatives of aromatic isocyanates and 14 times greater than 1-2MP derivatives of aliphatic

isocyanates]. The compound-to-compound variability of UV response per isocyanate group for MAP

derivatives is smaller than the variability of any other commonly used reagent/detector combination

(the coefficient of variation is 3,5 % for five model isocyanates). This results in more accurate

quantification of detectable non-monomeric isocyanate species based on a calibration curve generated

from analysing standards of monomeric species. The monomeric species used for calibration is generally

the one associated with the product being analysed, but others could be used due to the very small

compound-to-compound response variability of the MAP derivatives. The intensity of fluorescence

response of MAP derivatives is comparable to that of MAMA derivatives and considerably greater

than other reagents (e.g. approximately 30 times more intense than that of tryptamine derivatives).

The compound-to-compound variability in fluorescence response has been found to be smaller than

that of MAMA derivatives but larger than that of tryptamine derivatives (MAMA = 59 % coefficient

of variation, MAP = 33 % coefficient of variation, and tryptamine = 16 % coefficient of variation for

5 model isocyanates). The compound-to-compound fluorescence variability of MAP derivatives is

considered too great for accurate quantification of non-monomeric isocyanate species based on

calibration with monomer standards. However, the sensitivity of the fluorescence detection makes

it especially suitable for quantification of low levels of monomer, and the selectivity is very useful to

designate an unidentified HPLC peak as a MAP derivative. MAP derivatives also give a strong response

by electrochemical detection. The pH gradient used in the HPLC analysis selectively accelerates the

elution of amines (MAP derivatives are amines) and is very strong (it accelerates MDI more than

100-fold). Re-equilibration to initial conditions is almost immediate. Many oligomeric species can be

measured in the 30 min MAP analysis that may be unobservable in a much longer isocratic analysis.

MAP has been used in several studies comparing it side-by-side with other methods. Reference [9]

found MAP impingers and NIOSH 5521 impingers (comparable to MDHS 25) to give comparable

results in spray painting environments. Reference [9] used MAP reagent, but the pH gradient was not

employed. Reference [10] compared MAP impingers with several other impinger methods (NIOSH 5521

and NIOSH 5522) and the double filter method. The average MAP oligomer value was substantially

higher than the other impinger methods and slightly higher than the double filter method. The pH

gradient was used in these MAP analyses. Reference [11] found that the MAP oligomer results compared

favourably against several other methods for measurement of oligomeric isocyanates in the collision

repair industry, and agreed well with the reference values.
[12]

The MAP method is currently available as NIOSH Method 5525 . The performance characteristics of

the method have been evaluated in Reference [13].
vi © ISO 2019 – All rights reserved
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SIST ISO 17735:2019
INTERNATIONAL STANDARD ISO 17735:2019(E)
Workplace atmospheres — Determination of total
isocyanate groups in air using 1-(9-anthracenylmethyl)
piperazine (MAP) reagent and liquid chromatography
1 Scope

This document specifies a method for the sampling and analysis of airborne organic isocyanates in

workplace air.

This document is applicable to a wide range of organic compounds containing isocyanate groups,

including monofunctional isocyanates (e.g. phenyl isocyanate), diisocyanate monomers [e.g.

1,6-hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate

(MDI), and isophorone diisocyanate (IPDI)], prepolymers (e.g. the biuret and isocyanurate of HDI), as

well as chromatographable intermediate products formed during production or thermal breakdown of

polyurethane.

In mixed systems of HDI and IPDI products, it is impossible to identify and quantify low levels of IPDI

monomer using this document, due to coelution of IPDI monomer with HDI-uretidinedione.

It is known that the method underestimates the oligomer in MDI-based products. Total isocyanate

group (NCO) is underestimated in MDI-based products by about 35 % as compared to dibutylamine

titration.

The method has been successfully modified to be used with LC-MS-MS for TDI monomer using an

isocratic 70 % acetonitrile/30 % 10 mM ammonium formate mobile phase.

The useful range of the method, expressed in moles of isocyanate group per species per sample, is

−10 −7

approximately 1 × 10 to 2 × 10 . The instrumental detection limit for the monomers using both

ultraviolet (UV) detection and fluorescence (FL) detection is about 2 ng monomer per sample. The

useful limit of detection for the method using reagent impregnated filters is about 10 ng to 20 ng

monomer per sample for both UV and FL detection. For a 15 l sample, this corresponds to 0,7 µg/m to

1,4 µg/m . For impinger samples, which require solid phase extraction, experience has shown that the

useful limit of detection is about 30 ng to 80 ng monomer per sample.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

EN 1232, Workplace atmospheres — Pumps for personal sampling of chemical agents — Requirements and

test methods
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
© ISO 2019 – All rights reserved 1
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SIST ISO 17735:2019
ISO 17735:2019(E)
4 Principle

A measured volume of air is drawn through either an impinger containing a solution of

1-(9-anthracenylmethyl)piperazine (MAP), a filter impregnated with MAP, or a sampling train

consisting of an impinger followed by an impregnated filter. The choice of sampler depends on the

chemical and physical characteristics of the airborne isocyanate[14]. If an impinger is used, the

solution is subjected to solid-phase extraction (SPE) and the eluate is concentrated and analysed by

reverse phase high performance liquid chromatography (HPLC) with ultraviolet (UV) absorbance

and fluorescence (FL) detection in series. If an i
...

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