SIST ISO 17734-2:2013
Determination of organonitrogen compounds in air using liquid chromatography and mass spectrometry - Part 2: Amines and aminoisocyanates using dibutylamine and ethyl chloroformate derivatives
Determination of organonitrogen compounds in air using liquid chromatography and mass spectrometry - Part 2: Amines and aminoisocyanates using dibutylamine and ethyl chloroformate derivatives
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 (ISO 17734-1). The method can be used for simultaneous determinations of amines, 4,4'-methylenediphenyldiamine (4,4'-MDA), 2,4- and 2,6-toluenediamine (2,4-, 2,6-TDA) and 1,6-hexamethylenediamine (1,6-HDA), and compounds containing both isocyanate and amine groups, 4,4'-methylenediphenyl aminoisocyanate (4,4'-MAI), 2,4-, 4,2- and 2,6-toluene aminoisocyanate (2,4, 4,2, 2,6-TAI), 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 50 fmol and for the aminoisocyanate, it is about 3 fmol. For a 15-l air sample, this corresponds to 0,4 ng.m–3 for TDA and 0,03 ng.m–3 for TAI.
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
Določevanje organskih dušikovih spojin v zraku s tekočinsko kromatografijo in masno spektrometrijo - 2. del: Določevanje aminov in aminoizocianatov preko derivatov dibutilamina in etilkloroformiata
Ta del standarda ISO 17734 podaja splošne napotke za vzorčenje in analizo aminov in aminoizocianatov v zraku na delovnem mestu. Zelo se priporoča, da se določevanje aminov in aminoizocianatov izvaja skupaj z določevanjem izocianatov v zraku, pri čemer se za reagent uporablja DBA (standard ISO 17734-1). Metodo je mogoče uporabiti za hkratno določevanje aminov, tj. 4,4'-metilendifenildiamin (4,4'-MDA), 2,4- in 2,6-toluendiamin (2,4-, 2,6-TDA) in 1,6-heksametilendiamin (1,6-HDA), ter spojin, ki vsebujejo skupine izocianatov in aminov, tj. 4,4'-metilendifenil aminoizocianat (4,4'-MAI), 2,4-, 4,2- in 2,6-toluen aminoizocianat (2,4, 4,2, 2,6-TAI), 1,6-heksametilen aminoizocianat (1,6-HAI). Metoda je ustrezna za zbiranje aminov in aminoizocianatov v plinski fazi in fazi delcev. Meja detekcije instrumentov za amine je približno 50 fmol, za aminoizocianate pa 3 fmol. Pri vzorcu zraka s 15 l to ustreza 0,4 ng.m–3 za TDA in 0,03 ng.m–3 za TAI.
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INTERNATIONAL ISO
STANDARD 17734-2
First edition
2006-03-01
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 17734-2:2006(E)
©
ISO 2006
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ISO 17734-2:2006(E)
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ii © ISO 2006 – All rights reserved
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ISO 17734-2:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 1
4 Reagents and materials . 3
5 Standard solutions . 3
5.1 Reference compounds . 3
5.2 Preparation of amine and deuterium-labelled amine derivatives . 4
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 . 6
7.1 Pre-sampling laboratory preparation. 6
7.2 Pre-sampling field preparations. 7
7.3 Collection of air samples . 7
7.4 Blanks . 7
7.5 Raw material. 7
7.6 Shipment of samples. 7
8 Laboratory sample preparation. 8
8.1 Sample sequence. 8
8.2 Work-up procedure. 8
9 Instrumental settings. 9
9.1 HPLC program (LC-MS). 9
9.2 HPLC program (LC-chemiluminescent nitrogen detector) (LC-CLND) . 9
9.3 Mass spectrometer . 9
10 Data handling . 10
10.1 Identification. 10
10.2 Calibration curves. 10
10.3 Quantification. 10
11 Determination of performance characteristics. 10
11.1 Introduction . 10
11.2 Relevant uncertainty contributions and criteria. 11
11.3 Assessment of performance characteristics, following the detailed approach in
Reference [12] . 11
Annex A (informative) Performance characteristics. 19
Annex B (informative) Examples . 21
Bibliography . 27
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ISO 17734-2:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17734-2 was prepared by Technical Committee ISO/TC 146, Air Quality, Subcommittee SC 2, Workplace
Atmospheres.
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
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ISO 17734-2:2006(E)
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 (ISO 17734-1). Using the DBA-method and derivatization with ethyl chloroformate in the
following work-up procedure makes simultaneous determination of amines, aminoisocyanates and
[6], [7]
isocyanates possible .
For quantification of amine and aminoisocyanate derivatives, reference compounds are necessary, but are
only available for a few diamines. Aminoisocyanates can not 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,
[6]
together with MS characterization, in greatly facilitating the production of reference solutions .
© ISO 2006 – All rights reserved v
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INTERNATIONAL STANDARD ISO 17734-2:2006(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
(ISO 17734-1).
The method can be used for simultaneous determinations of amines, 4,4'-methylenediphenyldiamine
(4,4'-MDA), 2,4- and 2,6-toluenediamine (2,4-, 2,6-TDA) and 1,6-hexamethylenediamine (1,6-HDA), and
compounds containing both isocyanate and amine groups, 4,4'-methylenediphenyl aminoisocyanate
(4,4'-MAI), 2,4-, 4,2- and 2,6-toluene aminoisocyanate (2,4, 4,2, 2,6-TAI), 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 50 fmol and for the
–3
aminoisocyanate, it is about 3 fmol. For a 15-l air sample, this corresponds to 0,4 ng⋅m for TDA and
–3
0,03 ng⋅m for TAI.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 16200-1:2001, Workplace air quality — Sampling and analysis of volatile organic compounds by solvent
desorption/gas chromatography — Part 1: Pumped sampling method
ISO 5725-2:1994, 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 (including
Technical Corrigendum 1:2002)
3 Principle
The method permits the simultaneous sampling and analysis of amines, aminoisocyanates and isocyanates.
Only amines and aminoisocyanates are discussed in this part, 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 filter.
–1
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
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ISO 17734-2:2006(E)
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 monitoring 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.
Figure 1 — Principle of the described method
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ISO 17734-2:2006(E)
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.
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, 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
ET derivatives are easily prepared by direct derivatization with ethyl chloroformate (ET) for the 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 must be characterized before using
as calibration standards. Isocyanate, aminoisocyanate and amine derivatives for compounds that not are
commercially available can be made from the bulk material or from the thermal decomposition of PUR.
Alternatively, standard solutions can be purchased.
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ISO 17734-2:2006(E)
5.2 Preparation of amine and deuterium-labelled amine derivatives
Calibration standards are made by spiking accurately weighed amounts (ca 0,1 mmol) of amines in 100 ml of
–1
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.
Synthesis of derivatives:
⎯ 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 ethyl chloroformate
dropwise under continuous stirring.
⎯ After 10 min, separate the toluene phase.
⎯ Evaporate the reaction mixture to dryness in a rotating evaporator, and dry the residue under vacuum.
5.3 Aminoisocyanate derivatives
5.3.1 Preparation
Dissolve 0,5 mmol of the isocyanates 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.
To produce both the isomers for the 2,4-TAI, prepare another solution by first allowing the isocyanate solution
to react with 0,5 mmol of ethanol during 16 h. Then add excess DBA to the solution. Evaporate the solution to
dryness and dissolve in methanol. The solution is 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
[8], [9], [10]
(e.g. caffeine) can be used as external standard. The technique is used in several applications .
5.4 Thermal decomposition products of polyurethane (PUR)
5.4.1 Preparation of mixed isocyanate, amine and aminoisocyanate derivatives
During the thermal decomposition of, e.g. 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⋅DBA⋅l and follow this by the work up procedure described in 7.2. The solution is characterized as
described in 5.3.2.
5.4.2 Characterization
Qualitative data are obtained with LC-MS. Obtained structural data together with the LC-CLND data makes it
possible to calculate the concentrations of different components in the solution. The characterized 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 six months.
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ISO 17734-2:2006(E)
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. A luer-lock fitting is attached to the outlet of the impinger.
6.1.4 Sampling pump.
–1
Use a sampling pump with a calibrated flow rate of 1 l⋅min .
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
medium 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.
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ISO 17734-2:2006(E)
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 × 1,0 mm with 3 µm particles).
18
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 continuum scans (typically
50-1 500 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.
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
must 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 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 of
–1
0,01 mol l DBA as extraction solution tubes for the filters.
®
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 2006 – All rights reserved
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ISO 17734-2:2006(E)
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 should be
–1
1 l min .
7.3 Collection of air samples
7.3.1 Sampling
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
worksite where isocyanates can be emitted into the air. 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. A sufficient number of samples
must be collected in order to make a representative exposure assessment.
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 sampling
period, measure the flow and turn off the pump. Transfer 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 of field blanks collected. 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.
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 may 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.
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ISO 17734-2:2006(E)
a
The impinger solution is transferred to the impinger flask.
b
The airflow is measured and the sampling pump is calibrated to 1 l/min.
c
Air sampling.
d
The airflow is measured.
e
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 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
...
SLOVENSKI STANDARD
SIST ISO 17734-2:2013
01-april-2013
'RORþHYDQMHRUJDQVNLKGXãLNRYLKVSRMLQY]UDNXVWHNRþLQVNRNURPDWRJUDILMRLQ
PDVQRVSHNWURPHWULMRGHO 'RORþHYDQMHDPLQRYLQDPLQRL]RFLDQDWRYSUHNR
GHULYDWRYGLEXWLODPLQDLQHWLONORURIRUPLDWD
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 17734-2:2006
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
SIST ISO 17734-2:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 17734-2:2013
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SIST ISO 17734-2:2013
INTERNATIONAL ISO
STANDARD 17734-2
First edition
2006-03-01
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 17734-2:2006(E)
©
ISO 2006
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SIST ISO 17734-2:2013
ISO 17734-2:2006(E)
PDF disclaimer
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Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 1
4 Reagents and materials . 3
5 Standard solutions . 3
5.1 Reference compounds . 3
5.2 Preparation of amine and deuterium-labelled amine derivatives . 4
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 . 6
7.1 Pre-sampling laboratory preparation. 6
7.2 Pre-sampling field preparations. 7
7.3 Collection of air samples . 7
7.4 Blanks . 7
7.5 Raw material. 7
7.6 Shipment of samples. 7
8 Laboratory sample preparation. 8
8.1 Sample sequence. 8
8.2 Work-up procedure. 8
9 Instrumental settings. 9
9.1 HPLC program (LC-MS). 9
9.2 HPLC program (LC-chemiluminescent nitrogen detector) (LC-CLND) . 9
9.3 Mass spectrometer . 9
10 Data handling . 10
10.1 Identification. 10
10.2 Calibration curves. 10
10.3 Quantification. 10
11 Determination of performance characteristics. 10
11.1 Introduction . 10
11.2 Relevant uncertainty contributions and criteria. 11
11.3 Assessment of performance characteristics, following the detailed approach in
Reference [12] . 11
Annex A (informative) Performance characteristics. 19
Annex B (informative) Examples . 21
Bibliography . 27
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17734-2 was prepared by Technical Committee ISO/TC 146, Air Quality, Subcommittee SC 2, Workplace
Atmospheres.
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
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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 (ISO 17734-1). Using the DBA-method and derivatization with ethyl chloroformate in the
following work-up procedure makes simultaneous determination of amines, aminoisocyanates and
[6], [7]
isocyanates possible .
For quantification of amine and aminoisocyanate derivatives, reference compounds are necessary, but are
only available for a few diamines. Aminoisocyanates can not 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,
[6]
together with MS characterization, in greatly facilitating the production of reference solutions .
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INTERNATIONAL STANDARD ISO 17734-2:2006(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
(ISO 17734-1).
The method can be used for simultaneous determinations of amines, 4,4'-methylenediphenyldiamine
(4,4'-MDA), 2,4- and 2,6-toluenediamine (2,4-, 2,6-TDA) and 1,6-hexamethylenediamine (1,6-HDA), and
compounds containing both isocyanate and amine groups, 4,4'-methylenediphenyl aminoisocyanate
(4,4'-MAI), 2,4-, 4,2- and 2,6-toluene aminoisocyanate (2,4, 4,2, 2,6-TAI), 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 50 fmol and for the
–3
aminoisocyanate, it is about 3 fmol. For a 15-l air sample, this corresponds to 0,4 ng⋅m for TDA and
–3
0,03 ng⋅m for TAI.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 16200-1:2001, Workplace air quality — Sampling and analysis of volatile organic compounds by solvent
desorption/gas chromatography — Part 1: Pumped sampling method
ISO 5725-2:1994, 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 (including
Technical Corrigendum 1:2002)
3 Principle
The method permits the simultaneous sampling and analysis of amines, aminoisocyanates and isocyanates.
Only amines and aminoisocyanates are discussed in this part, 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 filter.
–1
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
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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 monitoring 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.
Figure 1 — Principle of the described method
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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.
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, 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
ET derivatives are easily prepared by direct derivatization with ethyl chloroformate (ET) for the 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 must be characterized before using
as calibration standards. Isocyanate, aminoisocyanate and amine derivatives for compounds that not are
commercially available can be made from the bulk material or from the thermal decomposition of PUR.
Alternatively, standard solutions can be purchased.
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5.2 Preparation of amine and deuterium-labelled amine derivatives
Calibration standards are made by spiking accurately weighed amounts (ca 0,1 mmol) of amines in 100 ml of
–1
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.
Synthesis of derivatives:
⎯ 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 ethyl chloroformate
dropwise under continuous stirring.
⎯ After 10 min, separate the toluene phase.
⎯ Evaporate the reaction mixture to dryness in a rotating evaporator, and dry the residue under vacuum.
5.3 Aminoisocyanate derivatives
5.3.1 Preparation
Dissolve 0,5 mmol of the isocyanates 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.
To produce both the isomers for the 2,4-TAI, prepare another solution by first allowing the isocyanate solution
to react with 0,5 mmol of ethanol during 16 h. Then add excess DBA to the solution. Evaporate the solution to
dryness and dissolve in methanol. The solution is 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
[8], [9], [10]
(e.g. caffeine) can be used as external standard. The technique is used in several applications .
5.4 Thermal decomposition products of polyurethane (PUR)
5.4.1 Preparation of mixed isocyanate, amine and aminoisocyanate derivatives
During the thermal decomposition of, e.g. 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⋅DBA⋅l and follow this by the work up procedure described in 7.2. The solution is characterized as
described in 5.3.2.
5.4.2 Characterization
Qualitative data are obtained with LC-MS. Obtained structural data together with the LC-CLND data makes it
possible to calculate the concentrations of different components in the solution. The characterized 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 six months.
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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. A luer-lock fitting is attached to the outlet of the impinger.
6.1.4 Sampling pump.
–1
Use a sampling pump with a calibrated flow rate of 1 l⋅min .
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
medium 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.
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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 × 1,0 mm with 3 µm particles).
18
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 continuum scans (typically
50-1 500 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.
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
must 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 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 of
–1
0,01 mol l DBA as extraction solution tubes for the filters.
®
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.
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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 should be
–1
1 l min .
7.3 Collection of air samples
7.3.1 Sampling
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
worksite where isocyanates can be emitted into the air. 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. A sufficient number of samples
must be collected in order to make a representative exposure assessment.
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 sampling
period, measure the flow and turn off the pump. Transfer 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 of field blanks collected. 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.
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 may 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 coll
...
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