Workplace air — Analysis of airborne water immiscible mineral oil droplets and vapor with Fourier — Transform infrared spectroscopy

The method described in this document quantifies the absolute exposure to mineral oil vapours and droplets, within a concentration range from 0,5 mg/m3 to 125 mg/m3, in the inhalable fraction of the workplace air. This document contains comprehensive information and instructions on the equipment and chemicals to be used. This method is applicable for water soluble oils and metal working fluids.

Air des lieux de travail — Analyse par transformée de Fourier des vapeurs et des gouttelettes d'huile minérale non miscibles à l'eau en suspension dans l'air — Spectroscopie infrarouge à transformée de Fourier

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Status
Published
Publication Date
18-Apr-2021
Current Stage
6060 - International Standard published
Start Date
19-Apr-2021
Completion Date
19-Apr-2021
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INTERNATIONAL ISO
STANDARD 23506
First edition
2021-04
Workplace air — Analysis of airborne
water immiscible mineral oil droplets
and vapor with Fourier — Transform
infrared spectroscopy
Air des lieux de travail — Analyse par transformée de Fourier des
vapeurs et des gouttelettes d'huile minérale non miscibles à l'eau
en suspension dans l'air — Spectroscopie infrarouge à transformée
de Fourier
Reference number
ISO 23506:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23506:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23506:2021(E)
Contents Page

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

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

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

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

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

4 Principle ........................................................................................................................................................................................................................ 1

5 Apparatus and reagents ................................................................................................................................................................................ 2

5.1 Collecting materials for analysis and other chemicals ......................................................................................... 2

5.2 Sampler equipment ............................................................................................................................................................................. 3

5.3 Analytical equipment ........................................................................................................................................................................ 3

5.4 Other equipment ................................................................................................................................................................................... 4

6 Polymer resin preparation ........................................................................................................................................................................ 5

6.1 Drying ............................................................................................................................................................................................................. 5

6.2 Sieving ............................................................................................................................................................................................................ 5

6.3 Purification of unused polymer resin .................................................................................................................................. 5

6.3.1 General...................................................................................................................................................................................... 5

6.3.2 Step 1: Preparatory purification with ethanol ....................................................................................... 5

6.3.3 Step 2: Purifying with tetrachloroethene ................................................................................................... 5

7 Sampling ........................................................................................................................................................................................................................ 6

7.1 Sampler preparation .......................................................................................................................................................................... 6

7.1.1 Glass fibre filter (droplets) ...................................................................................................................................... 6

7.1.2 Polymer resin (vapours) ........................................................................................................................................... 6

7.1.3 Marking .................................................................................................................................................................................... 6

7.1.4 Cleaning ................................................................................................................................................................................... 6

7.1.5 Assembly ................................................................................................................................................................................. 6

7.2 Sampling ....................................................................................................................................................................................................... 6

7.2.1 Parameters ............................................................................................................................................................................ 6

7.2.2 Pump .......................................................................................................................................................................................... 7

7.2.3 Initial flow rate .................................................................................................................................................................. 7

7.2.4 Flow rate verification ................................................................................................................................................... 7

7.2.5 Storage and transport .................................................................................................................................................. 7

8 Analysis .......................................................................................................................................................................................................................... 7

8.1 FTIR scanning parameters ............................................................................................................................................................ 7

8.2 Preparation ................................................................................................................................................................................................ 7

8.2.1 Sample....................................................................................................................................................................................... 7

8.2.2 Solvent blank ....................................................................................................................................................................... 7

8.2.3 Collection substrate blank ....................................................................................................................................... 7

8.3 Calibration .................................................................................................................................................................................................. 8

8.3.1 General...................................................................................................................................................................................... 8

8.3.2 Stock solution ..................................................................................................................................................................... 8

8.3.3 Calibration standards .................................................................................................................................................. 8

8.3.4 Calibration with liquid paraffin ........................................................................................................................... 9

8.4 Measurement ............................................................................................................................................................................................ 9

8.4.1 General...................................................................................................................................................................................... 9

8.4.2 Instrument background ............................................................................................................................................. 9

8.4.3 Filling the cuvette ............................................................................................................................................................ 9

8.4.4 Calibration ............................................................................................................................................................................. 9

8.4.5 Sample measurement .................................................................................................................................................. 9

9 Evaluation .................................................................................................................................................................................................................10

9.1 Calibration ...............................................................................................................................................................................................10

9.2 Samples ......................................................................................................................................................................................................10

© ISO 2021 – All rights reserved iii
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ISO 23506:2021(E)

10 Interferences .........................................................................................................................................................................................................11

Annex A (informative) Validation .........................................................................................................................................................................12

Annex B (informative) Example for estimation of expanded uncertainty..................................................................20

Bibliography .............................................................................................................................................................................................................................24

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23506:2021(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 of 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 www .iso .org/

iso/ foreword .html.

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

Workplace atmospheres.

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 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 23506:2021(E)
Introduction

Mineral oils are by-products from the distillation of crude oil. The mineral oils produced in this way are

used in a wide range of modern applications. Their composition varies according to their application.

Mineral oils contain saturated hydrocarbons, cyclic saturated hydrocarbons, aromatic compounds, and

unsaturated hydrocarbons.

They are used as fuels, for example in the form of petroleum, diesel and kerosene for internal

combustion engines, as heating oil, and as lubricants in the metal processing and application industries.

Mineral oils are also found in cosmetics and medical applications. This wide range of applications

gives rise to exposure for human beings and the natural environment to mineral oils in the form of

vapours and droplets. Since mineral oils and their constituents are harmful to health, it is important for

quantification of the exposure to be possible and where necessary for corrective measures to be taken.

The method described in this document is intended to support swift, cost-effective and straightforward

quantification of the concentration of mineral oil in a large number of samples. This method has

been validated in accordance with the provisions of EN 13936 and ISO 20581 and has an expanded

measurement uncertainty in the region of 20 % to 30 % within the measurement range stated.

vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 23506:2021(E)
Workplace air — Analysis of airborne water immiscible
mineral oil droplets and vapor with Fourier — Transform
infrared spectroscopy
1 Scope

The method described in this document quantifies the absolute exposure to mineral oil vapours and

3 3

droplets, within a concentration range from 0,5 mg/m to 125 mg/m , in the inhalable fraction of the

workplace air.

This document contains comprehensive information and instructions on the equipment and chemicals

to be used.
This method is applicable for water soluble oils and metal working fluids.
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.

ISO 1042, Laboratory glassware — One-mark volumetric flasks

ISO 7708, Air quality — Particle size fraction definitions for health-related sampling

ISO 13137:2013, Workplace atmospheres — Pumps for personal sampling of chemical and biological

agents — Requirements and test methods
ISO 18158, Workplace air — Terminology

ISO 20581, Workplace air — General requirements for the performance of procedures for the measurement

of chemical agents

EN 13936, Workplace exposure — Procedures for measuring a chemical agent present as a mixture of

airborne particles and vapour — Requirements and test methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 18158 apply.

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/
4 Principle

A defined airflow is drawn over the sampler with the aid of a pump. The droplets are deposited on the

glass fibre filter, the vapours on the polymer resin. By extraction of the glass fibre filter and the polymer

resin, the adsorbed mineral oils are desorbed and can be analysed by means of Fourier trasnform

infrared spectrocopy (FTIR) and evaluated.
© ISO 2021 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 23506:2021(E)

The Gesamtstaub-Gas-Probenahme (GGP) sampling system enables both droplets and vapours to be

collected but any other personal sampler capable of collecting the inhalable droplets and vapours

simultenously can be used. A glass fibre filter is used to collect the droplets. A downstream sampling

tube containing polymer resin is used to collect the vapours and more volatile components in the

mineral oil. The GGP system cannot be used for distinction between exposure to gases and droplets,

since droplets collected during sampling can vaporize from the filter and collect on the polymer resin.

Following extraction, the samples are analysed by Fourier transform infrared spectroscopy (FTIR) in

-1 -1

the wavenumber range from 3 000 cm to 2 800 cm . This method is not specific for mineral oil, since

it detects all substances with C-H bonds collected on the sampler.

The principle of the method described here for the quantification of mineral oil is based upon activation

of the C-H bonds of the hydrocarbons in the mineral oil. Hydrocarbons absorb light in the wavenumber

-1 -1

range from 3 000 cm to 2 800 cm . This enables the concentration of mineral oil at the site of sampling

to be determined by external calibration against a defined mineral oil at known concentrations.

The method described in this document is based upon the "MAK Collection for Occupational Health and

Safety 2016, Vol 1, No 1", "Cooling lubricants and other complex hydrocarbon mixtures, immiscible with

[2]
water – droplets and vapours" .
5 Apparatus and reagents
5.1 Collecting materials for analysis and other chemicals
5.1.1 Glass fibre filter.

The droplets shall be collected by a binder-free 85/90 glass fibre filter with a diameter of 37 mm.

Glass fibre filters generally have no blank value. This shall however be verified beforehand.

5.1.2 Polymer resin.

Poly[styrene-divinylbenzene], a mesoporous polymer resin in the particle size range from 0,5 mm to

0,9 mm shall be used for collection of the vapour.

Polymer resins are well suited as a collection phase for mineral oils. This has been demonstrated with

reference to Amberlite® XAD-2 . XAD-2 requires cleaning prior to use in case it exhibits a blank value.

Any other polymer resin equivalent to XAD-2 can be accepted if it is validated according to Annex A.

5.1.3 Tetrachloroethene.

Tetrachloroethene, also know as perchloroethylene, in the purest grade (≥99,0 %) is used to extract the

samples and to prepare the calibration standards, and to clean the polymer resin if necessary.

Any other solvent can be used if it is validated according to Annex A.
5.1.4 Mineral oil, for calibration purposes.

The mineral oil used for evaluation of the air samples shall be that used at the workplace.

Fresh unused mineral oil is usually preferred for practical reasons.

If there are several mineral oil products used, it is recommended to use the one with the lower mineral

oil content. This leads to a conservative result.

1) Amberlite® XAD-2 is the trade name of a product supplied by Sigma Aldrich. This information is given for

the convenience of users of this document and does not constitute an endorsement by ISO of the product named.

Equivalent products may be used if they can be shown to lead to the same results.

2 © ISO 2021 – All rights reserved
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ISO 23506:2021(E)
5.1.5 Liquid paraffin standard.

In case it not be possible to obtain a site-specific oil sample or if this sample is not soluble in

tetrachloroethene, a mineral oil standard for spectroscopy, namely liquid paraffin, CAS number 8012-

95-1, should be used for evaluation.

The different response factors against the mineral oils of the workplaces which were used for this

validation are listed in Table A.13 and Table A.14.
5.2 Sampler equipment
The following equipment is required for sampling.

The performance of the samplers used shall match the criteria for inhalable fraction as specified in

ISO 7708.
5.2.1 Sampling pump, conforming with the requirements of ISO 13137.

5.2.2 Personal sampler, shall be used for the simultaneous collection of inhalable droplets and

vapours. Any personal sampler capable of collecting the inhalable droplets and vapours simultaneously

may be used; for the validation experiments written in this document, the GGP sampling system, with

[4]
matching cone for the specified flow rate (3,5 l/min) was used .
[11]

The GGP sampler is a modification of the GSP sampler (see CEN/TR 15230 ), which match the criteria

[9]

of ISO 7708. Sampling efficiency of this modification was determined by George C. Dragan et al. (2015) .

5.2.2.1 Various lengths of tubes (e.g. outer diameter: 9 mm or 10 mm; inner diameter: 6 mm), for

connecting the personal sampler to the pump.

5.2.2.2 Matching filter capsule for the 37 mm glass fibre filter, for insertion into the personal sampler.

5.2.2.3 Plastic cartridge manufactured from polyvinylidene fluoride (PVDF).

Matching plastic tube (outer diameter: 20 mm; inner diameter: 16 mm, length: 70 mm) for the polymer

resin for insertion into the personal sampling system, with high-grade steel sieve stopper and plastic

sealing caps.

5.2.2.4 Silicone adapter, which shall fit onto the sampler head to connect the flow meter for

measuring/setting the air flow.

5.2.3 Flow meter, conforming with the requirements for test instruments in ISO 13137:2013, 6.2.

5.2.4 Glass metering aid, for filling the plastic cartridge with 8 ml polymer resin.

5.2.5 A 500 ml glass Erlenmeyer flask for the tilting dispenser head.
5.3 Analytical equipment

5.3.1 Dispenser, for organic solvents, with a volume of 1 ml to 10 ml, shall be used for extraction of

the samples and preparation of the calibration.

5.3.2 Piston pipettes with tips for organic solvents, with a volume range of 30 µl to 300 µl and of

0,5 ml to 5,0 ml are required for preparation of the calibration.
© ISO 2021 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 23506:2021(E)
5.3.3 30 ml screw-cap glass vials.

The filter and the polymer resin shall be transferred separately to the 30 ml extraction vessels for

extraction.
5.3.4 Screw cap with septum, for sealing extraction vessels.

The extraction vessels shall be sealed by means of plastic screw caps and a PTFE septa.

5.3.5 Refrigerator, at 4 °C to 8 °C.
5.3.6 Fourier transform infrared spectrometer (FTIR)
-1 -1
Spectral range 7 800 cm – 350 cm
Spectral resolution: Better than 0,8 cm
-1 -1
Sensitivity: S/N ratio 2 200 cm – 2 100 cm
— 8 000: 1 peak to peak in 5 s
— 22 000: 1 peak to peak in 1 min
Detector: Deuterated triglycine sulfate (DTGS) detector

5.3.7 A suitable quartz-glass cuvette for infrared spectrometry with 10 mm path length and

polytetrafluoroethylene (PTFE) cuvette stoppers.

5.3.8 One 5 ml glass syringe with Luer-lock cone and cannula for filling the cuvette.

5.3.9 Glass beakers, 150 ml and 50 ml.

5.2.10 Glass volumetric flasks with glass stoppers, 100 ml ± 0,1 ml, A, ISO 1042, in 20 °C, with glass

stopper.
5.3.11 100 ml glass Erlenmeyer flask with ground joint, with glass stopper.

5.3.12 Analytical balance, capable of weighing at least to 320 g with a precision of 0,1 mg.

5.4 Other equipment

5.4.1 1 000 ml Erlenmeyer flask with ground joint, for treating the polymer resin with

tetrachloroethene and ethanol.

5.4.2 Ultrasonic bath, with sufficient capacity to hold two 1 000 ml erlenmeyer flasks.

5.4.3 Drying cabinet or oven with fan-assisted circulation and extractor, set at 60 °C.

5.4.4 1 l glass vacuum flask with matching rubber stopper.

5.4.5 Porcelain Büchner funnel, for round filters (diameter: 125 mm; volume: approximately

1 000 ml) for vacuum filtration of the polymer resin following treatment with tetrachloroethene and

ethanol.
5.4.6 Round glass fibre filters, for vacuum filtration (diameter: 125 mm).
4 © ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 23506:2021(E)
5.4.7 Water-jet pump or vacuum pump.

Where a water-jet pump is used, an absorption bottle shall be placed between the vacuum flask and the

water-jet pump in order to prevent tetrachloroethene from entering the waste water.

5.4.8 Rubber hose, for connecting the vacuum flask to the water-jet pump/vacuum pump.

5.4.9 Sieve, with mesh: 0,5 mm to 0,9 mm.

5.4.10 A large porcelain Petri dish (diameter: 30 cm) for drying the polymer resin.

5.4.11 A glass powder funnel is required for polymer resin transfer.
6 Polymer resin preparation
6.1 Drying

Polymer resin is generally supplied in the damp state and shall therefore first be dried. The polymer

resin shall be dried in a large Petri dish at 60 °C in the drying cabinet (5.4.3).

6.2 Sieving

Polymer resin in the particle size range from 0,5 mm to 0,9 mm shall be used for sampling; the dried

polymer resin shall therefore be sieved.

NOTE If the cartridges are filled with polymer resin with a particle size of <0,5 mm, the pump can fail to

reach or maintain the desired flow rate owing to excessive pressure drop.
6.3 Purification of unused polymer resin
6.3.1 General

In the as-delivered state, polymer resin is not free of a blank value in the measurement range of

-1 -1
2 800 cm to 3 000 cm , and shall therefore be purified prior to use.
Ethanol (≥ 99,5 %) is required for initial purification of the polymer resin.
6.3.2 Step 1: Preparatory purification with ethanol

Fresh polymer resin shall first be treated with ethanol in order to eliminate the blank value. For this

purpose, approximately 400 ml of the sieved polymer resin shall be placed in a 1 000 ml Erlenmeyer

flask and ethanol added until the polymer resin floats. This shall then be treated in the ultrasonic bath

at 50 °C for 1 h and then filtered using the Buchner funnel. This process shall be performed a total of

four times using fresh solvent. The vapours shall be routed into the extractor. The polymer resin shall

then be dried for 24 h at 60 °C in the drying cabinet (5.4.3).
6.3.3 Step 2: Purifying with tetrachloroethene

Polymer resin that has been purified with ethanol shall also be treated subsequently with

tetrachloroethene. The procedure is the same as for purification with ethanol. Polymer resin purified

with tetrachloroethene shall be dried for at least 7 days in the drying cabinet with fan-assisted

circulation.

NOTE The purification step with tetrachloroethene described here is also be employed for used polymer

resin in preparation for use in further analyses.
© ISO 2021 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO 23506:2021(E)

The transmission spectrum of the blank value of the polymer resin is generally a negative spectrum. If

this is not the case, purification shall be repeated. The laboratory should document purified polymer

resin shelf-life if it is not used directly after purification.
7 Sampling
7.1 Sampler preparation
7.1.1 Glass fibre filter (droplets)

The glass fibre filter shall be placed in the filter capsule, fixed, and sealed for transport with the caps.

7.1.2 Polymer resin (vapours)

Approximately 8 ml polymer resin, corresponding approximately to 3,2 g, shall be placed in the plastic

cartridge. The cartridge shall be closed at both ends with the high-grade steel sieve stoppers. The

cartridges shall be closed with plastic stoppers for transport. For alternative personal samplers, the

amount of polymer resin may be altered as appropriate following the requirements of ISO 20581.

7.1.3 Mar
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23506
ISO/TC 146/SC 2
Workplace air — Analysis of airborne
Secretariat: ANSI
water immiscible mineral oil droplets
Voting begins on:
2021­01­22 and vapor with Fourier — Transform
infrared spectroscopy
Voting terminates on:
2021­03­19
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23506:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 23506:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23506:2021(E)
Contents Page

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

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

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

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

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

4 Principle ........................................................................................................................................................................................................................ 1

5 Apparatus and reagents ................................................................................................................................................................................ 2

5.1 Collecting materials for analysis and other chemicals ......................................................................................... 2

5.2 Sampler equipment ............................................................................................................................................................................. 3

5.3 Analytical equipment ........................................................................................................................................................................ 3

5.4 Other equipment ................................................................................................................................................................................... 4

6 Polymer resin preparation ........................................................................................................................................................................ 5

6.1 Drying ............................................................................................................................................................................................................. 5

6.2 Sieving ............................................................................................................................................................................................................ 5

6.3 Purification of unused polymer resin .................................................................................................................................. 5

6.3.1 General...................................................................................................................................................................................... 5

6.3.2 Step 1: Preparatory purification with ethanol ....................................................................................... 5

6.3.3 Step 2: Purifying with tetrachloroethene ................................................................................................... 5

7 Sampling ........................................................................................................................................................................................................................ 6

7.1 Sampler preparation .......................................................................................................................................................................... 6

7.1.1 Glass fibre filter (droplets) ...................................................................................................................................... 6

7.1.2 Polymer resin (vapours) ........................................................................................................................................... 6

7.1.3 Marking .................................................................................................................................................................................... 6

7.1.4 Cleaning ................................................................................................................................................................................... 6

7.1.5 Assembly ................................................................................................................................................................................. 6

7.2 Sampling ....................................................................................................................................................................................................... 6

7.2.1 Parameters ............................................................................................................................................................................ 6

7.2.2 Pump .......................................................................................................................................................................................... 7

7.2.3 Initial flow rate .................................................................................................................................................................. 7

7.2.4 Flow rate verification ................................................................................................................................................... 7

7.2.5 Storage and transport .................................................................................................................................................. 7

8 Analysis .......................................................................................................................................................................................................................... 7

8.1 FTIR scanning parameters ............................................................................................................................................................ 7

8.2 Preparation ................................................................................................................................................................................................ 7

8.2.1 Sample....................................................................................................................................................................................... 7

8.2.2 Solvent blank ....................................................................................................................................................................... 7

8.2.3 Collection substrate blank ....................................................................................................................................... 7

8.3 Calibration .................................................................................................................................................................................................. 8

8.3.1 General...................................................................................................................................................................................... 8

8.3.2 Stock solution ..................................................................................................................................................................... 8

8.3.3 Calibration standards .................................................................................................................................................. 8

8.3.4 Calibration with liquid paraffin ........................................................................................................................... 9

8.4 Measurement ............................................................................................................................................................................................ 9

8.4.1 General...................................................................................................................................................................................... 9

8.4.2 Instrument background ............................................................................................................................................. 9

8.4.3 Filling the cuvette ............................................................................................................................................................ 9

8.4.4 Calibration ............................................................................................................................................................................. 9

8.4.5 Sample measurement .................................................................................................................................................. 9

9 Evaluation .................................................................................................................................................................................................................10

9.1 Calibration ...............................................................................................................................................................................................10

9.2 Samples ......................................................................................................................................................................................................10

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23506:2021(E)

10 Interferences .........................................................................................................................................................................................................11

Annex A (informative) Validation .........................................................................................................................................................................12

Annex B (informative) Example for estimation of expanded uncertainty..................................................................20

Bibliography .............................................................................................................................................................................................................................24

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23506:2021(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 non­governmental, 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 of 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 www .iso .org/

iso/ foreword .html.

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

Workplace atmospheres.

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.
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ISO/FDIS 23506:2021(E)
Introduction

Mineral oils are by-products from the distillation of crude oil. The mineral oils produced in this way are

used in a wide range of modern applications. Their composition varies according to their application.

Mineral oils contain saturated hydrocarbons, cyclic saturated hydrocarbons, aromatic compounds, and

unsaturated hydrocarbons.

They are used as fuels, for example in the form of petroleum, diesel and kerosene for internal

combustion engines, as heating oil, and as lubricants in the metal processing and application industries.

Mineral oils are also found in cosmetics and medical applications. This wide range of applications

gives rise to exposure for human beings and the natural environment to mineral oils in the form of

vapours and droplets. Since mineral oils and their constituents are harmful to health, it is important for

quantification of the exposure to be possible and where necessary for corrective measures to be taken.

The method described in this document is intended to support swift, cost­effective and straightforward

quantification of the concentration of mineral oil in a large number of samples. This method has

been validated in accordance with the provisions of EN 13936 and ISO 20581 and has an expanded

measurement uncertainty in the region of 20 % to 30 % within the measurement range stated.

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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23506:2021(E)
Workplace air — Analysis of airborne water immiscible
mineral oil droplets and vapor with Fourier — Transform
infrared spectroscopy
1 Scope

The method described in this document quantifies the absolute exposure to mineral oil vapours and

3 3

droplets, within a concentration range from 0,5 mg/m to 125 mg/m , in the inhalable fraction of the

workplace air.

This document contains comprehensive information and instructions on the equipment and chemicals

to be used.
This method is applicable for water soluble oils and metal working fluids.
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.

ISO 1042, Laboratory glassware — One-mark volumetric flasks

ISO 7708, Air quality — Particle size fraction definitions for health-related sampling

ISO 13137:2013, Workplace atmospheres — Pumps for personal sampling of chemical and biological

agents — Requirements and test methods
ISO 18158, Workplace air — Terminology

ISO 20581, Workplace air — General requirements for the performance of procedures for the measurement

of chemical agents

EN 13936, Workplace exposure — Procedures for measuring a chemical agent present as a mixture of

airborne particles and vapour — Requirements and test methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 18158 apply.

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/
4 Principle

A defined airflow is drawn over the sampler with the aid of a pump. The droplets are deposited on the

glass fibre filter, the vapours on the polymer resin. By extraction of the glass fibre filter and the polymer

resin, the adsorbed mineral oils are desorbed and can be analysed by means of FTIR and evaluated.

The Gesamtstaub-Gas-Probenahme (GGP) sampling system enables both droplets and vapours to be

collected but any other personal sampler capable of collecting the inhalable droplets and vapours

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ISO/FDIS 23506:2021(E)

simultenously can be used. A glass fibre filter is used to collect the droplets. A downstream sampling

tube containing polymer resin is used to collect the vapours and more volatile components in the

mineral oil. The GGP system cannot be used for distinction between exposure to gases and droplets,

since droplets collected during sampling can vaporize from the filter and collect on the polymer resin.

Following extraction, the samples are analysed by Fourier transform infrared spectroscopy (FTIR) in

­1 ­1

the wavenumber range from 3 000 cm to 2 800 cm . This method is not specific for mineral oil, since

it detects all substances with C­H bonds collected on the sampler.

The principle of the method described here for the quantification of mineral oil is based upon activation

of the C-H bonds of the hydrocarbons in the mineral oil. Hydrocarbons absorb light in the wavenumber

­1 ­1

range from 3 000 cm to 2 800 cm . This enables the concentration of mineral oil at the site of sampling

to be determined by external calibration against a defined mineral oil at known concentrations.

The method described in this document is based upon the "MAK Collection for Occupational Health and

Safety 2016, Vol 1, No 1", "Cooling lubricants and other complex hydrocarbon mixtures, immiscible with

[2]
water – droplets and vapours" .
5 Apparatus and reagents
5.1 Collecting materials for analysis and other chemicals
5.1.1 Glass fibre filter.

The droplets shall be collected by a binder-free 85/90 glass fibre filter with a diameter of 37 mm.

Glass fibre filters generally have no blank value. This shall however be verified beforehand.

5.1.2 Polymer resin.

Poly[styrene-divinylbenzene], a mesoporous polymer resin in the particle size range from 0,5 mm to

0,9 mm shall be used for collection of the vapour.

Polymer resins are well suited as a collection phase for mineral oils. This has been demonstrated with

reference to Amberlite® XAD­2 . XAD-2 requires cleaning prior to use in case it exhibits a blank value.

Any other polymer resin equivalent to XAD-2 can be accepted if it is validated according to Annex A.

5.1.3 Tetrachloroethene.

Tetrachloroethene, also know as perchloroethylene, in the purest grade (≥99,0 %) is used to extract the

samples and to prepare the calibration standards, and to clean the polymer resin if necessary.

Any other solvent can be used if it is validated according to Annex A.
5.1.4 Mineral oil, for calibration purposes.

The mineral oil used for evaluation of the air samples shall be that used at the workplace.

Fresh unused mineral oil is usually preferred for practical reasons.

If there are several mineral oil products used, it is recommended to use the one with the lower mineral

oil content. This leads to a conservative result.

1) Amberlite® XAD-2 is the trade name of a product supplied by Sigma Aldrich This information is given for

the convenience of users of this document and does not constitute an endorsement by ISO of the product named.

Equivalent products may be used if they can be shown to lead to the same results.

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ISO/FDIS 23506:2021(E)
5.1.5 Liquid paraffin standard.

In case it not be possible to obtain a site-specific oil sample or if this sample is not soluble in

tetrachloroethene, a mineral oil standard for spectroscopy, namely liquid paraffin, CAS number 8012-

95­1, should be used for evaluation.

The different response factors against the mineral oils of the workplaces which were used for this

validation are listed in Table A.13 and Table A.14.
5.2 Sampler equipment
The following equipment is required for sampling.

The performance of the samplers used shall match the criteria for inhalable fraction as specified in

ISO 7708.
5.2.1 Sampling pump, conforming with the requirements of ISO 13137.

5.2.2 Personal sampler, shall be used for the simultaneous collection of inhalable droplets and

vapours. Any personal sampler capable of collecting the inhalable droplets and vapours simultaneously

may be used; for the validation experiments written in this document, the GGP sampling system, with

[4]
matching cone for the specified flow rate (3,5 l/min) was used .
[11]

The GGP sampler is a modification of the GSP sampler (see CEN/TR 15230 ), which match the criteria

[9]

of ISO 7708. Sampling efficiency of this modification was determined by George C. Dragan et al. (2015) .

5.2.2.1 Various lengths of tubes (e.g. outer diameter: 9 mm or 10 mm; inner diameter: 6 mm), for

connecting the personal sampler to the pump.

5.2.2.2 Matching filter capsule for the 37 mm glass fibre filter, for insertion into the personal sampler.

5.2.2.3 Plastic cartridge manufactured from polyvinylidene fluoride (PVDF).

Matching plastic tube (outer diameter: 20 mm; inner diameter: 16 mm, length: 70 mm) for the polymer

resin for insertion into the personal sampling system, with high-grade steel sieve stopper and plastic

sealing caps.

5.2.2.4 Silicone adapter, which shall fit onto the sampler head to connect the flow meter for

measuring/setting the air flow.

5.2.3 Flow meter, conforming with the requirements for test instruments in ISO 13137:2013, 6.2.

5.2.4 Glass metering aid, for filling the plastic cartridge with 8 ml polymer resin.

5.2.5 A 500 ml glass Erlenmeyer flask for the tilting dispenser head.
5.3 Analytical equipment

5.3.1 Dispenser, for organic solvents, with a volume of 1 ml to 10 ml, shall be used for extraction of

the samples and preparation of the calibration.

5.3.2 Piston pipettes with tips for organic solvents, with a volume range of 30 µl to 300 µl and of

0,5 ml to 5,0 ml are required for preparation of the calibration.
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ISO/FDIS 23506:2021(E)
5.3.3 30 ml screw-cap glass vials.

The filter and the polymer resin shall be transferred separately to the 30 ml extraction vessels for

extraction.
5.3.4 Screw cap with septum, for sealing extraction vessels.

The extraction vessels shall be sealed by means of plastic screw caps and a PTFE septa.

5.3.5 Refrigerator, at 4 °C to 8 °C.
5.3.6 Fourier transform infrared spectrometer (FTIR)
­1 ­1
Spectral range 7 800 cm – 350 cm
Spectral resolution: Better than 0,8 cm
­1 ­1
Sensitivity: S/N ratio 2 200 cm – 2 100 cm
— 8 000: 1 peak to peak in 5 s
— 22 000: 1 peak to peak in 1 min
Detector: Deuterated triglycine sulfate (DTGS) detector

5.3.7 A suitable quartz-glass cuvette for infrared spectrometry with 10 mm path length and

polytetrafluoroethylene (PTFE) cuvette stoppers.

5.3.8 One 5 ml glass syringe with Luer-lock cone and cannula for filling the cuvette.

5.3.9 Glass beakers, 150 ml and 50 ml.

5.2.10 Glass volumetric flasks with glass stoppers, 100 ml ± 0,1 ml, A, ISO 1042, in 20 °C, with glass

stopper.
5.3.11 100 ml glass Erlenmeyer flask with ground joint, with glass stopper.

5.3.12 Analytical balance, capable of weighing at least to 320 g with a precision of 0,1 mg.

5.4 Other equipment

5.4.1 1 000 ml Erlenmeyer flask with ground joint, for treating the polymer resin with

tetrachloroethene and ethanol.

5.4.2 Ultrasonic bath, with sufficient capacity to hold two 1 000 ml erlenmeyer flasks (cross reference

to be included).

5.4.3 Drying cabinet or oven with fan­assisted circulation and extractor, set at 60 °C.

5.4.4 1 l glass vacuum flask with matching rubber stopper.

5.4.5 Porcelain Büchner funnel, for round filters (diameter: 125 mm; volume: approximately

1 000 ml) for vacuum filtration of the polymer resin following treatment with tetrachloroethene and

ethanol.
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ISO/FDIS 23506:2021(E)
5.4.6 Round glass fibre filters, for vacuum filtration (diameter: 125 mm).
5.4.7 Water-jet pump or vacuum pump.

Where a water-jet pump is used, an absorption bottle shall be placed between the vacuum flask and the

water-jet pump in order to prevent tetrachloroethene from entering the waste water.

5.4.8 Rubber hose, for connecting the vacuum flask to the water-jet pump/vacuum pump.

5.4.9 Sieve
Mesh: > 0,5 mm

5.4.10 A large porcelain Petri dish (diameter: 30 cm) for drying the polymer resin.

5.4.11 A glass powder funnel is required for polymer resin transfer.
6 Polymer resin preparation
6.1 Drying

Polymer resin is generally supplied in the damp state and shall therefore first be dried. The polymer

resin shall be dried in a large Petri dish at 60 °C in the drying cabinet (5.4.3).

6.2 Sieving

Polymer resin in the particle size range from 0,5 mm to 0,9 mm shall be used for sampling; the dried

polymer resin shall therefore be sieved.

NOTE If the cartridges are filled with polymer resin with a particle size of <0,5 mm, the pump can fail to

reach or maintain the desired flow rate owing to excessive pressure drop.
6.3 Purification of unused polymer resin
6.3.1 General

In the as-delivered state, polymer resin is not free of a blank value in the measurement range of

­1 ­1
2 800 cm to 3 000 cm , and shall therefore be purified prior to use.
Ethanol (≥ 99,5 %) is required for initial purification of the polymer resin.
6.3.2 Step 1: Preparatory purification with ethanol

Fresh polymer resin shall first be treated with ethanol in order to eliminate the blank value. For this

purpose, approximately 400 ml of the sieved polymer resin shall be placed in a 1 000 ml Erlenmeyer

flask and ethanol added until the polymer resin floats. This shall then be treated in the ultrasonic bath

at 50 °C for 1 h and then filtered using the Buchner funnel. This process shall be performed a total of

four times using fresh solvent. The vapours shall be routed into the extractor. The polymer resin shall

then be dried for 24 h at 60 °C in the drying cabinet (5.4.3).
6.3.3 Step 2: Purifying with tetrachloroethene

Polymer resin that has been purified with ethanol shall also be treated subsequently with

tetrachloroethene. The procedure is the same as for purification with ethanol. Polymer resin purified

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ISO/FDIS 23506:2021(E)

with tetrachloroethene shall be dried for at least 7 days in the drying cabinet with fan-assisted

circulation.

NOTE The purification step with tetrachloroethene described here is also be employed for used polymer

resin in preparation for use in further analyses.

The transmission spectrum of the blank value of the polymer resin is generally a negative spectrum. If

this is not the case, purification shall be repeated. The laboratory should document purified polymer

resin shelf-life if it is not used directly after purification.
7 Sampling
7.1 Sampler preparation
7.1.1 Glass fibre filter (droplets)

The glass fibre filter shall be placed in the filter capsule, fixed, and sealed for transport with the caps.

7.1.2 Polymer resin (vapours)
Approx
...

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