SIST ISO 17734-2:2015

SLOVENSKI STANDARD
01-marec-2015
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SIST ISO 17734-2:2013
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Determination of organonitrogen compounds in air using liquid chromatography and
mass spectrometry - Part 2: Amines and aminoisocyanates using dibutylamine and ethyl
chloroformate derivatives
Détermination des composés organiques azotés dans l'air par chromatographie liquide
et spectrométrie de masse - Partie 2: Amines et aminoisocyanates par les dérivés de la
dibutylamine et du chloroformate d'éthyle
Ta slovenski standard je istoveten z: ISO 17734-2:2013
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 17734-2
Second edition
2013-12-01
Determination of organonitrogen
compounds in air using liquid
chromatography and mass
spectrometry —
Part 2:
Amines and aminoisocyanates
using dibutylamine and ethyl
chloroformate derivatives
Détermination des composés organiques azotés dans l’air par
chromatographie liquide et spectrométrie de masse —
Partie 2: Amines et aminoisocyanates par les dérivés de la
dibutylamine et du chloroformate d’éthyle
Reference number
©
ISO 2013
© ISO 2013
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Published in Switzerland
ii © ISO 2013 – 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 Standard solutions. 3
5.1 Reference compounds . 3
5.2 Amine and deuterium-labelled amine derivatives . 3
5.3 Aminoisocyanate derivatives . 4
5.4 Thermal decomposition products of polyurethane (PUR). 4
5.5 Stability of the amine and aminoisocyanate derivatives . 4
6 Apparatus . 5
7 Air sampling . 7
7.1 Pre-sampling laboratory preparation . 7
7.2 Pre-sampling field preparations . 7
7.3 Collection of air samples . 7
7.4 Blanks . . 8
7.5 Raw material . 8
7.6 Shipment of samples . 8
8 Laboratory sample preparation . 9
8.1 Sample sequence . 9
8.2 Work-up procedure .10
9 Instrumental settings .10
9.1 HPLC program (LC-MS) .10
9.2 HPLC program [LC-chemiluminescent nitrogen detector (LC-CLND)] .10
9.3 Mass spectrometer .10
10 Data handling .11
10.1 Identification .11
10.2 Calibration curves .11
10.3 Quantification .11
11 Determination of performance characteristics.11
11.1 General .11
11.2 Relevant uncertainty contributions and criteria .12
11.3 Assessment of performance characteristics (following the detailed approach in Reference
[12]) .12
Annex A (informative) Performance characteristics
........................................................................................................................20
Annex B (informative) Examples .22
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.
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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 2,
Workplace atmospheres.
This second edition of ISO 17734-2 cancels and replaces ISO 17734-2:2006, which has been
technically revised.
ISO 17734 consists of the following parts, under the general title Determination of organonitrogen
compounds in air using liquid chromatography and mass spectrometry:
— Part 1: Isocyanates using dibutylamine derivatives
— Part 2: Amines and aminoisocyanates using dibutylamine and ethyl chloroformate derivatives
iv © ISO 2013 – All rights reserved

Introduction
In many applications, when considering isocyanates as a workplace contaminant, there is also a need to
investigate the presence of aminoisocyanates and amines. During thermal decomposition of polyurethane
[1][2][3][4][5][6]
(PUR), not only isocyanates, but also amines and aminoisocyanates, are formed.
The determination of isocyanates in the work environment using DBA as a reagent has been
demonstrated to be a robust method (see ISO 17734-1). Using the DBA method and derivatization with
ethyl chloroformate in the following work-up procedure makes simultaneous determination of amines,
[6][7]
aminoisocyanates, and isocyanates possible.
For quantification of amine and aminoisocyanate derivatives, reference compounds are necessary,
but are only available for a few diamines. Aminoisocyanates cannot be analysed directly because they
react with themselves. In this method, a nitrogen-specific detector has been used for quantification of
amine and aminoisocyanate derivatives in reference solutions. This technique has been demonstrated
to be a useful tool, together with MS characterization, in greatly facilitating the production of reference
[6]
solutions.
INTERNATIONAL STANDARD ISO 17734-2:2013(E)
Determination of organonitrogen compounds in air using
liquid chromatography and mass spectrometry —
Part 2:
Amines and aminoisocyanates using dibutylamine and
ethyl chloroformate derivatives
1 Scope
This part of ISO 17734 gives general guidance for the sampling and analysis of airborne amines and
aminoisocyanates in workplace air. It is strongly recommended that the determination of amines and
aminoisocyanates is made together with the determination of isocyanates in air, using DBA as a reagent
(see ISO 17734-1).
The method can be used for simultaneous determinations of amines, such as 4,4’-methylenediphenyldiamine
(4,4’-MDA), 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA), and 1,6-hexamethylenediamine (1,6-
HDA), and compounds containing both isocyanate and amine groups, such as 4,4’-methylenediphenyl
aminoisocyanate (4,4’-MAI), 2,4-, 4,2-, and 2,6-toluene aminoisocyanate (2,4-, 4,2-, and 2,6-TAI), and
1,6-hexamethylene aminoisocyanate (1,6-HAI). The method is suitable for collecting amines and
aminoisocyanates in both the gas and particle phases. The instrumental detection limit for the amines
is about 5 nmol/sample and for the aminoisocyanate, it is about 0,3 nmol/sample. For a 15 l air sample,
–3 –3
this corresponds to 0,4 ng⋅m for TDA and 0,03 ng⋅m for TAI.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 16200-1, Workplace air quality — Sampling and analysis of volatile organic compounds by solvent
desorption/gas chromatography — Part 1: Pumped sampling method
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
3 Principle
The method permits the simultaneous sampling and analysis of amines, aminoisocyanates, and
isocyanates. Only amines and aminoisocyanates are discussed in this part of ISO 17734, because
isocyanates are considered in ISO 17734-1.
Samples are collected by drawing a known volume of air through a midget impinger flask followed by a
–1
filter. The impinger contains 10 ml of 0,01 mol⋅l of di-n-butylamine (DBA) in toluene, and the filter is a
glass fibre filter with no binder. After sampling, deuterium-labelled amine-ethyl chloroformate (ET) and
isocyanate-DBA derivatives (used as internal standard) are added to the sample solutions. The excess
reagent and solvent are evaporated, and the samples are dissolved in acetonitrile. The samples are
analysed using reversed-phase liquid chromatography (LC) and electrospray (ESP) mass spectrometric
(MS) detection, monitoring positive ions. Quantification is made by quantifying selected ions.
Quantification and qualitative determinations can be performed using different LC-MS techniques. LC-
CLND (chemiluminescent nitrogen detection) or, for aromatic isocyanates, aminoisocyanates, and amines,
LC-UV (ultraviolet detection) can be used for the determination of higher concentrations. Reference
materials can be characterized using LC-MS/CLND. For characterization of volatile compounds, a GC-
thermoionic specific detector (TSD) can also be used.

Gas phase and large particles (>1,5
Sampling
µ m ) are collected in the impinger
with impinger and filter flask. Small particles (0,01 µm
to 1,5 µm) are collected . on the filter
Standard solution:
Calibration curve Transfer of sample solution Isocyanate-DBA, amine-ET and
aminoisocyanate-DBA-ET
from standard solution and filter to test tube
derivatives
Internal standard, IS:
- Similar in retention time
- Similar in molecular structure
Addition of IS
i.e. aromatic or aliphatic
- Preferably deuterium-labelled
derivative
-Extraction of analytes on the filter
-Derivatisation of the amine groups
with ET in a two phase
Work-up procedure
derivatisation procedure
- Change of solution media
- Enrichment of the analytes
+
- SIM of molecular ion [ MH ]
Analysis with LC-MS
of analytes and IS
- Calculation of the area ratio of the
analyte and IS
Evaluation of data
- Comparison between area ratio of
the air sample and calibration plot
Figure 1 — Principle of the described method
4 Reagents and materials
4.1 DBA reagent.
Analytical grade di-n-butylamine is commercially available.
4.2 Ethyl chloroformate reagent.
Analytical grade ethyl chloroformate is commercially available.
2 © ISO 2013 – All rights reserved

4.3 Reagent solution.
In a 1 l volumetric flask, dilute 1,69 ml of DBA in toluene and make up to the mark. The solution is stable
and no special care during storage is necessary.
–1
4.4 Sodium hydroxide, 5 mol⋅l .
Dissolve 200 g of NaOH in water in a beaker, then transfer the solution to a 1 l volumetric flask and make
up to the mark.
4.5 Pyridine, analytical grade.
4.6 Solvents.
The reagent solvent, typically toluene, and other solvents, such as acetonitrile and methanol, should be
of liquid chromatographic quality.
4.7 Formic acid, concentrated formic acid, analytical grade.
4.8 Ethanol, absolute, extra pure 99,5 %.
4.9 HPLC mobile phases.
4.9.1 LC-MS.
The weak mobile phase (mobile phase A) consists of water/acetonitrile (95/5 volume fraction) and
0,05 % formic acid. The strong mobile phase (mobile phase B) consists of water/acetonitrile/methanol
(5/70/25 volume fraction) and 0,05 % formic acid. The mobile phases are degassed prior to use.
4.9.2 LC-CLND.
The weak mobile phase (mobile phase C) consists of water/methanol (95/5 volume fraction) and 0,05 %
formic acid. The strong mobile phase (mobile phase D) consists of water/methanol (5/95 volume fraction)
and 0,05 % formic acid. The mobile phases are degassed prior to use.
5 Standard solutions
5.1 Reference compounds
Reference compounds are necessary for LC-MS determination. For the commercially available amines,
the ethyl chloroformate (ET) derivatives are easily prepared by direct derivatization with ET for
use as calibration standards. The aminoisocyanate derivatives are prepared by reacting one of the
isocyanate groups with DBA and the other group with ethanol. The mixed derivatives formed shall be
characterized before use as calibration standards. Isocyanate, aminoisocyanate, and amine derivatives
for compounds that are not commercially available can be made from the bulk material or from the
thermal decomposition of PUR. Alternatively, standard solutions can be purchased.
5.2 Amine and deuterium-labelled amine derivatives
Calibration standards are made by spiking accurately weighed amounts (ca 0,1 mmol) of amines in
–1
100 ml of toluene. The solution is further diluted to ca 0,01 µmol⋅ml . 5 ml toluene solutions are spiked
with volumes of the amine solutions appropriate for the construction of a calibration curve. The work-
up procedure is then performed; this is described in 8.2.
The procedure for the synthesis of derivatives is as follows.
1) Dissolve a 10 mmol aliquot of the amines and the deuterium-labelled amines in 20 ml of toluene.
–1
Thereafter, add 150 µl pyridine and 40 ml of 5 mol⋅l NaOH. Then add 1,5 ml of ET dropwise under
continuous stirring.
2) After 10 min, separate the toluene phase.
3) Evaporate the reaction mixture to dryness in a rotating evaporator, and dry the residue under vacuum.
5.3 Aminoisocyanate derivatives
5.3.1 Preparation
Two procedures, A and B, are used to enrich different mixed aminoisocyanate derivatives. The isocyanate
groups in, for example, 2,4-TDI have different reactivity and two different derivatives can be formed.
In procedure A: Dissolve 0,5 mmol of the isocyanates (HDI, 2,4- and 2,6-TDI, and 4,4’-MDI) in 50 ml
isooctane. Add 0,5 mmol of DBA dissolved in isooctane under continuous stirring to the isocyanate
solutions. After 30 min, add excess ethanol to the solutions. Allow the mixtures to react for 16 h.
Evaporate the solutions to dryness and dissolve in methanol.
In procedure B: Dissolve 0,5 mmol of the isocyanate (2,4-TDI) in 50 ml of isooctane; 0,5 mmol of ethanol
dissolved in isooctane is added under continuous stirring to the isocyanate solution. After 16 h, excess
DBA dissolved in isooctane is added to the solution. The solution is allowed to react for 1 h. The solution
is evaporated under a gentle stream of nitrogen. The residue is dissolved in methanol.
The solutions are characterized as described in 5.3.2.
5.3.2 Characterization
Dilute the solutions in methanol to appropriate concentrations and characterize them on the LC-MS
and quantify them on the LC-CLND. This technique is nitrogen specific and any nitrogen-containing
compound (e.g. caffeine) can be used as external standard. The technique is used in several applications.
[8][9][10]
5.4 Thermal decomposition products of polyurethane (PUR)
5.4.1 Preparation of mixed isocyanate, amine, and aminoisocyanate derivatives
During the thermal decomposition of PUR, isocyanates, aminoisocyanates, and amines are formed
that are not commercially available. PUR-based material can be thermally decomposed at appropriate
temperatures. Collect emitted degradation products in impinger flasks (filters in series) containing
–1
0,5 mol⋅l DBA and follow this by the work-up procedure described in 7.2. The solution is characterized
as described in 5.4.2.
5.4.2 Characterization
Qualitative data are obtained with LC-MS. The obtained structural data together with the LC-CLND
data make it possible to calculate the concentrations of different components in the solution. The
characterized and diluted sample solution is used as a calibration standard for LC-MS.
5.5 Stability of the amine and aminoisocyanate derivatives
Solutions of amine-ET and ET-DBA-aminoisocyanate derivatives (MDA, 2,4- and 2,6-TDA, HDA, MAI,
2,4-, 4,2-, and 2,6-TAI, and HAI) have been found stable in toluene, acetonitrile, and methanol for 6 mo
(stored in a dark fridge).
4 © ISO 2013 – All rights reserved

6 Apparatus
6.1 Sampler.
Sample the air with an impinger flask followed by a filter.
6.1.1 Filter.
Use a 13 mm glass fibre filter (binder free) with a pore size of 0,3 µm.
6.1.2 Filter holder.
Use a 13 mm polypropylene filter holder with luer-lock connections.
6.1.3 Midget impingers.
A midget impinger consists of a tapered inlet tube. Match the two parts so that the distance between the
inlet and the receiver bottom is 1 mm to 2 mm. The filter holder is attached to the outlet of the impinger,
by using an impinger with a luer-lock fitting on the outlet. Alternatively, the filter holder is attached to
the outlet of the impinger by flexible tubing.
6.1.4 Sampling pump, complying to the requirements of ISO 13137, capable of maintaining the flow rate
–1 –1
at 1 l⋅min for impinger-filter sampling and 0,2 l⋅min for solvent-free sampling during the sampling time.
6.1.5 Tubing.
Use rubber tubing of suitable length and of appropriate diameter to ensure a leak-proof fit to both the
pump and the sampler outlet.
6.1.6 Vapour trap.
Use a vapour trap with an internal diameter of 17 mm and a length of 140 mm filled with charcoal (with
a median particle size <3 mm) between the sampler and the sampling pump.
6.2 Flow meter.
Use a portable flow meter capable of measuring the appropriate flow rate with acceptable accuracy.
6.3 Liquid chromatographic system.
In this method, a micro-LC system is used in order to improve the sensitivity, to minimize the maintenance
on the MS, and to minimize the consumption of the mobile phase. The micro-LC system is described in
the following paragraphs. If desired, this system can be replaced by a conventional LC system.
6.3.1 Autosampler.
6.3.1.1 LC-MS.
On-column focusing is performed by partially filled loops (typically 10 µl total volume) of 2 µl loop
injections between 4+4 µl of 50/30/20 water/acetonitrile/methanol. Any commercially available
autosampler capable of making partially filled loop injections and making sample injections of acceptable
accuracy and precision can be used.
6.3.1.2 LC-CLND.
On-column focusing is performed by partially filled loops (typically 10 µl total volume) of 2 µl loop
injections between 4+4 µl of 50/50 methanol/water. Any commercially available autosampler capable
of making partially filled loop injections and making sample injections of acceptable accuracy and
precision can be used.
6.3.2 Pumping system (LC-MS and LC-CLND).
–1
An HPLC pump capable of gradient elution with a flow rate of 100 µl⋅min is required.
6.3.3 Analytical column (LC-MS and LC-CLND).
An HPLC column capable of separating the different analytes is required.
1) ®
EXAMPLE An example of a suitable column is a PepMap C (50 mm × 1,0 mm with 3 µm particles).
6.3.4 Tubing.
Use short (<40 cm) tubing with a small internal diameter (typically ID <0,1 mm).
6.3.5 Detectors.
6.3.5.1 LC-MS.
Any modern MS equipped with a robust and stable electrospray interface will have the necessary
performance. The MS detection is performed with atmospheric pressure ionization, monitoring positive
ions. For quantification, selected ions are monitored. Full spectra are obtained using continuous scans
(typically 50 amu to 1 500 amu) for identification of unknown analytes. If wanted, a UV detector can be
used in series, prior to the MS. The UV detector needs to be equipped with a micro flow cell (typically
300 nl) to minimize peak band broadening.
6.3.5.2 LC-CLND.
Use a detector which is specific for bound nitrogen.
6.4 Ultrasonic bath.
Sonication of samples is necessary to make sure that isocyanate-DBA derivatives are dissolved in
the extraction solution and that the sample remaining after evaporation is properly dissolved in the
added solvent.
6.5 Evaporator.
Equipment for the evaporation of the sample solvent is necessary, preferably a vacuum centrifuge. A
gentle evaporation procedure is desirable since there is a risk that a tough evaporation can result in
losses of the most volatile isocyanate-DBA derivatives.
6.6 Glassware, glass beakers and volumetric flasks (volumetric flasks should conform to ISO 1042). ®
1) PepMap is an example of a suitable product available commercially. This information is given for the convenience
of users of this part of ISO 17734 and does not constitute an endorsement by ISO of this product.
6 © ISO 2013 – All rights reserved

7 Air sampling
7.1 Pre-sampling laboratory preparation
7.1.1 Cleaning of sampling equipment
Impingers should be taken apart and soaked in alkaline cleaning solution for a minimum of 2 h. The
upper part shall be rinsed with an alkaline cleaning solution, pure water, and finally deionized water. If
the nozzle is clogged, place it in an ultrasonic bath, and then continue with the cleaning procedure. The
lower part should be cleaned in a laboratory dishwasher. Both parts should be dried in an oven.
The filter cassettes and the gaskets should be immersed in ethanol in a glass beaker, sonicated for at
least 15 min, rinsed with deionized water, and dried in an oven.
7.1.2 Preparation of the reagent solution and extraction solution tubes
–1
Prepare test tubes containing 10 ml of 0,01 mol⋅l DBA as the reagent solution for the impingers. If the
gas phase and the particulate phase are to be collected separately, prepare test tubes containing 10 ml
–1
of 0,01 mol⋅l DBA as the extraction solution tubes for the filters.
7.2 Pre-sampling field preparations
Assemble the sampling system with the filter cassette containing the glass fibre filter coupled to the
outlet of the impinger. Transfer the reagent solution to the impinger.
Calibrate the pumps with the impinger-filter sampling system in line, using a portable flow meter. Fill
the impinger with the appropriate amount of reagent solution during calibration. The sampling rate
–1
should be 1 l⋅min .
7.3 Collection of air samples
7.3.1 Measurement task
In order to relate measurement results to occupational exposure limit values, take samples in the
worker’s breathing zone. In order to illustrate risks of being exposed, take stationary samples at
every place at the work-site where isocyanates can be emitted into the air and workers are potentially
exposed. It is also important to include operations that are not frequently performed, for example
repair and maintenance. Differences in materials and batch-to-batch variations are factors that also
should be taken into account when sampling. Collect a sufficient number of samples in order to make a
representative exposure assessment.
Stationary sampling can be collected as background samples or samples reflecting the worst-case
emission source. Background samples are normally collected at head height, taking into account the head
height of the workers’ position while carrying out the work tasks. Samples to detect emission sources
or worst-case scenarios are often collected close to the process and not necessarily representative for
workers’ exposure but for identification of “hot spots” where substances in the process are emitted.
7.3.2 Impinger-filter sampling
Position the sampling system, either attached to the worker with the inlet in the breathing zone for
personal sampling, or stationary for area sampling. Connect the pump to the sampling system, and place
a charcoal vapour trap in line between the pump and the sampling system in order to protect the pump
from the solvent vapour. Make sure that the equipment does not disturb the work operation, and that the
impinger can be held in a vertical position during the whole sampling period.
When ready to begin sampling, switch on the pump. Record the time of sampling. At the end of the
–1
sampling period, measure the flow rate. Rinse the impinger with 0,01 mol⋅l DBA in toluene. Transfer the
rinsing solution together with the impinger solution to a test tube, and immerse the glass fibre filter into
either the sampling solution or an extraction solution tube using tweezers. If the filter is transferred to
an extraction solution, it is possible to determine the amount of isocyanates in the particulate phase that
passes through the impinger (i.e. particles approx. 0,01 µm to 1,5 µm), separately from the gas phase
and large particles (>1,5 µm) sampled in the impinger. For an illustration of the sampling procedure, see
Figure 2. The volume drawn through the sampler is calculated from the sampling time and the average
sampling flow. The total sampling time is limited (about 30 min), unless the reagent solution is refilled
during sampling.
7.4 Blanks
From every series of samples, there should be an appropriate number, e.g. 3, of field blanks, lab blanks,
and chemical blanks.
Field blanks are samples that have been handled exactly like the other samples out in the field, except
that no air has been drawn through. Lab blanks will be useful to identify if there is contamination, if it
took place in the lab or in the field.
Chemical blanks are pure toluene with no addition of internal standard in the work-up.
7.5 Raw material
From each work-site, it is desirable to collect samples of the raw material suspected of emitting amines,
aminoisocyanates, and isocyanates during the work operation. Collecting and subsequent laboratory
testing of materials that are known or are suspected of emitting amines, aminoisocyanates, and
isocyanates is useful for assessing the exposure. The testing can consist of extraction, heating, or other
processing of the material, as similar to the original work operation as possible.
7.6 Shipment of samples
The test tubes containing the DBA-toluene samples should be shipped in individual plastic cases and
preferably kept in an upright position. The sampling solution tubes should be placed well apart from any
raw material collected. Regulations for shipping hazardous (dangerous) materials should be followed
as appropriate.
8 © ISO 2013 – All rights reserved

1 2 2
3 4
Key
The impinger solution is transferred to the impinger flask.
The airflow is measured and the sampling pump is calibrated to 1 l/min.
Air sampling
The airflow is measured.
The impinger solution is transferred to a test tube. The filter is either transferred to the impinger solution
tube or to an extraction solution tube.
Figure 2 — Illustration of the sampling procedure
8 Laboratory sample preparation
8.1 Sample sequence
In each sample sequence (typically 50 samples), a number of samples consist of field blanks, two chemical
blanks, two internal standard blanks, and an appropriate number of calibration standards. Internal
standard blanks are reagent solutions from the same batch as the reagent solution used for air sampling
spiked with internal standard in the work-up procedure. Chemical blanks are pure toluene with no
addition of internal standard in the work-up procedure.
8.2 Work-up procedure
–1
For the preparation of calibration standards, aliquots of 10 ml toluene solutions, containing 0,01 mol⋅l
DBA, are spiked with the amine derivatives and the aminoisocyanate derivatives to concentrations
appropriate for the calibration curve. For simultaneous isocyanate determination, the isocyanate-DBA
derivatives are also added to the standard solutions (see ISO 17734-1).
Upon receiving samples from the field, add deuterium-labelled amine derivatives (internal standard) to
the air samples, to the standard solutions, to the field blanks, and to the internal standard blanks. For
simultaneous isocyanate determination, the deuterium-labelled isocyanate derivatives are also added
to the solutions (see ISO 17734-1). Place the samples in an ultrasonic bath for 15 min. If the sample
solutions contain filters, place the samples in a centrifuge for 10 min (3 000 r/min). Remove the sample
solutions from the filters with a pipette into new test tubes. Carbamate esters are formed by a two-
–1
phase derivatisation procedure by the addition of 3 ml of 5 mol⋅l NaOH, 10 µl pyridine, and 50 µl ethyl
chloroformate. The samples are shaken for 15 min and the organic phase is separated and evaporated
to dryness. The residues are dissolved in 0,5 ml acetonitrile and placed in an ultrasonic bath for 15 min.
9 Instrumental settings
9.1 HPLC program (LC-MS)
For simultaneous determination of amine, aminoisocyanate, and isocyanate derivatives, the following
mobile phase composition can be used:
–1
— flow rate: 100 µl⋅min ;
— 0 min to 20 min: linear gradient from 40 % mobile phase B to 80 % mobile phase B;
— 20 min to 25 min: re-equilibrate at 40 % mobile phase B.
If single or a few derivatives are to be determined, isocratic elution or gradient elution with appropriate
mobile phase composition can be performed.
9.2 HPLC program [LC-chemiluminescent nitrogen detector (LC-CLND)]
For quantifying DBA derivatives in reference solutions prepared in-lab, generally at higher concentrations,
the following mobile phase composition can be used:
–1
— flow rate: 100 µl⋅min ;
— 0 min to 20 min: linear gradient from 40 % mobile phase D to 100 % mobile phase D;
— 20 min to 25 min: re-equilibrate at 40 % mobile phase D.
Depending on the properties of the analytes in the sample, stronger, weaker, or isocratic elution can be used.
9.3 Mass spectrometer
Settings of the MS depend greatly on the type of instrument that is used. Optimization is normally
–1
performed by the introduction of flow at 100 µl⋅min of mobile phase containing aromatic and aliphatic
amine and aminoisocyanate derivatives. Optimal settings vary for the analytes and the ions to be
monitored. Practical settings are not the optimum for all of the compounds to be studied.
+
For quantification, selected ions are monitored, e.g. the molecular ion [MH] , but other typical ions can
be used.
10 © ISO 2013 – All rights reserved

+ + +
For the DBA derivatives, typical formed ions are [MH] , [(DBA)H] (m/z = 130), [(DBA)CO] (m/z = 156),
+ +
[MH-129] , and [MNa] .
+ + + +
Typical ions for the amine derivatives are [MH] , [MNa] , [M-46] , and [M-92] .
+ + + + +
Typical ions for the aminoisocyanate derivatives are [MH] , [MNa] , [M-46] , [M-129] , [(DBA)H]
+
(m/z = 130), and [(DBA)CO] (m/z = 156) (see Annex B.4).
For identification of unknown isocyanates, full spectra are obtained using continuous scans (typically
50 amu to 1 500 amu).
10 Data handling
10.1 Identification
For identification, the retention times of sample peaks in the selected ion chromatograms are compared
to the standards and the internal standards.
10.2 Calibration curves
The peak areas of the amine and the aminoisocyanate derivatives and the internal standard are measured,
and the ratio is calculated. The ratio versus the concentration is plotted. A coefficient of correlation of
0,98 or better can be achieved. Values below 0,98 will increase the uncertainty, as calculated in 11.2.
Quadratic fit of the calibration curves can sometimes be necessary, usually because of a large dynamic
range. Type and condition of used instrumentation can affect the linearity of the calibration. Quadratic
calibration curves could be tolerated to some extent. However, care should be taken when using a
quadratic fit so that the performance of the method is not affected.
10.3 Quantification
Quantification is accomplished by comparing the area ratio of the sample peak and internal standard to
the calibration plot.
11 Determination of performance characteristics
11.1 General
The measurement of the concentration of amines, aminoisocyanates, and isocyanates in workplace air
[11]
has associated with it an uncertainty that can be expressed as combined uncertainty (see EN 482 or
Reference [12]). Thus, an uncertainty assessment has to be performed according to one or other of these
definitions of uncertainty. In both cases, this consists of the determination of uncertainty contributions
evaluated by means of laboratory and simulated field tests or from existing information. The values
obtained of the measurement uncertainty can then be compared with pre-set criteria, for example those
[11]
in EN 482 or those defined in national or international legislation.
11.2 Relevant uncertainty contributions and criteria
Uncertainty contribution Quantity Subclause Criterion
Sample volume V 11.3.2
sam
Sample flow – calibration q Relative uncertainty <2 %
cal
Sample flow – variation Δq <5 %
Sampling time t Relative uncertainty <0,1 %
Knowledge of temperature dur- T Relative uncertainty <4 %
ing sampling
Knowledge of pressure during p Relative uncertainty <2 %
sampling
Analyte mass m 11.3.3
sam
Analyte stability during storage k No significant difference between
AS
results of analysis of samples before
and after storage
Reaction/extraction efficiency E >90 % at the limit value with a relative
RE
uncertainty of <3 %
Mass of isocyanate in calibra- m Relative uncertainty <2 %
CS
tion standards
Calibration lack-of-fit LOF Relative residuals over the calibration
range <3 %; at the limit value <2 %
Response drift between calibra- D <3 %
R
tions
Analytical precision r <1 %
Selectivity s Resolution factor >1
Blank level m 11.3.4 <50 ng with a relative uncertainty
BL
of <5 %
Between-laboratory variations bl 11.3.5 Relative uncertainty <7,5 %
11.3 Assessment of performance characteristics (following the detailed approach in Ref-
erence [12])
11.3.1 Collection efficiency — relative to particle size distribution
For a complete description of the performance requirements and tests to be performed, see Reference [12].
12 © ISO 2013 – All rights reserved

11.3.2 Air sampling
11.3.2.1 Sampling volume
The sampled volume of air is calculated on the basis of measuring the sample flow rate before and after
sampling, as specified in ISO 16200-1, using Formula (1).
qq+
()
startend
V = ⋅t (1)
sam
where
V is the sampled volume of air (usually in millilitres);
sam
q is the sample flow rate at the beginning of the sampling period (usually in millilitres per
start
minute);
q is the sample flow rate at the end of the sampling period;
end
t is the sampling time (in minutes).
The uncertainty in the volume of air sampled is built up of contributions from
— the measurements of the flow rates before and after sampling,
— the measurement of the sampling time, and
— the variations in the flow rate during the sampling period.
It can be expressed using Formula (2).
2 22 2
u
uV uq +uq
() () () u
var,,q
sam startend
t
= ++ (2)
2 2 2 2
V t
qq+  
() qq+
sam ()
startend
startend
 
 
where the last term represents the uncertainty contribution due to flow rate variations during sampling.
11.3.2.2 Sampling time
The sampling time, t, can be measured to within ±0,5 min. For a sampling time of 8 h, the relative
uncertainty due to the measurement of t is about 0,1 % and is negligible.
11.3.2.3 Variations in flow rate during sampling
The flow rate during sampling is unknown. The uncertainty due to the variations in the flow rate during
sampling can be estimated by assuming a uniform distribution using Formula (3).
qq−
()
2 startend
u = (3)
var,q
11.3.2.4 Conversion of sample volume to STP
For the conversion of concentrations to STP, knowledge
...