Water quality - Determination of total organic carbon (TOC), dissolved organic carbon (DOC), total bound nitrogen (TNb) and dissolved bound nitrogen (DNb) after high temperature catalytic oxidative combustion (ISO 20236:2018)

This International Standard specifies a method for the determination of total organic carbon (TOC), dissolved organic carbon (DOC), and for the determination of dissolved and particular bound nitrogen (TNb) in the form of free ammonia, ammonium, nitrite, nitrate and organic compounds capable of conversion to nitrogen oxides under the oxidative conditions described. The procedure is carried out instrumentally.
NOTE 1 Generally the method can be applied for the determination of total carbon (TC) and total inorganic carbon (TIC) (see Annex A in the Outline).
The method is applicable for water (e.g. drinking water, raw water, ground water, surface water, sea water or waste water) containing suspended material of ≤ 100 μm of particle size (convention). Reduce particles of > 100 μm of size to pieces of particle size of ≤ 100 μm before injection. The method allows a determination of TOC/DOC ≥ 1 mg/l C and TNb ≥ 1 mg/l N.
NOTE 2 The determination of carbon concentrations > 0,3 mg/l to 1 mg/l is only applicable in special cases, for example drinking water, measured by highly sensitive instruments. Cyanide, cyanate and particles of elemental carbon (soot), when present in the sample, can be determined together with the organic carbon. Volatile or purgeable organic carbon (VOC, POC) is not determined by this method. Dissolved nitrogen gas is not determined by this method. Generally, the working range is restricted by instrument dependant conditions (e.g. injection volume). Higher concentrations may be determined after appropriate dilution.

Wasserbeschaffenheit - Bestimmung des gesamten organischen Kohlenstoffs (TOC), des gelösten organischen Kohlenstoffs (DOC), des gebundenen Stickstoffs (TNb) und des gelösten gebundenen Stickstoffs (DNb) nach katalytischer oxidativer Hochtemperaturverbrennung (ISO 20236:2018)

Dieses Dokument legt ein Verfahren zur Bestimmung des gesamten organischen Kohlenstoffs (TOC), und des gelösten organischen Kohlenstoffs (DOC) fest sowie des gesamten gebundenen Stickstoffs (TNb) und des gelösten gebundenen Stickstoffs (DNb), der in Form von freiem Ammoniak, Ammonium, Nitrit, Nitrat vorliegt oder in organischen Verbindungen, die unter den beschriebenen Bedingungen in Stickstoffoxide umgewandelt werden können. Das Verfahren wird instrumentell durchgeführt.
ANMERKUNG   Grundsätzlich kann das Verfahren für die Bestimmung des Gesamtkohlenstoffs (TC) und des gesamten anorganischen Kohlenstoffs (TIC) angewendet werden (siehe Anhang A).
Das Verfahren ist anwendbar für Wasserproben (z. B. Trinkwasser, Rohwasser, Grundwasser, Oberflächen¬wasser, Meerwasser, Abwasser, Sickerwässer).
Das Verfahren erlaubt die Bestimmung von TOC und DOC ≥ 1 mg/l und von TNb und DNb ≥ 1 mg/l. Nach oben ist der Arbeitsbereich durch geräteabhängige Bedingungen (z. B. Injektionsvolumen) begrenzt. Höhere Konzentrationen können nach entsprechender Verdünnung der Probe bestimmt werden.
Bei Proben, die flüchtige organische Verbindungen enthalten (z. B. Industrieabwasser), wird das Differenzverfahren angewandt (siehe Anhang A).
Cyanid, Cyanat und Partikel aus elementarem Kohlenstoff (Ruß) können, falls in der Probe vorhanden, zusammen mit dem organischen Kohlenstoff erfasst werden.
Das Verfahren eignet sich nicht für die Bestimmung von bei den Bedingungen des Verfahrens flüchtigem oder austreibbarem organischem Kohlenstoff.
Gelöster, gasförmiger Stickstoff (N2) wird nicht erfasst.

Qualité de l'eau - Dosage du carbone organique total (COT), carbone organique (COD), azote lié total (TNb) et azote lié dissous (DNb) après combustion oxidatif catalytique à haute temperature (ISO 20236:2018)

Kakovost vode - Določevanje celotnega organskega ogljika (TOC), raztopljenega organskega ogljika (DOC), celotnega vezanega dušika (TNb) in raztopljenega vezanega dušika (DNb) po katalitskem sežigu pri visoki temperaturi (ISO 20236:2018)

General Information

Status
Published
Public Enquiry End Date
01-Oct-2021
Publication Date
12-Dec-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
08-Dec-2021
Due Date
12-Feb-2022
Completion Date
13-Dec-2021

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SLOVENSKI STANDARD
SIST EN ISO 20236:2022
01-januar-2022
Nadomešča:
SIST EN 12260:2003
Kakovost vode - Določevanje celotnega organskega ogljika (TOC), raztopljenega
organskega ogljika (DOC), celotnega vezanega dušika (TNb) in raztopljenega
vezanega dušika (DNb) po katalitskem sežigu pri visoki temperaturi (ISO
20236:2018)

Water quality - Determination of total organic carbon (TOC), dissolved organic carbon

(DOC), total bound nitrogen (TNb) and dissolved bound nitrogen (DNb) after high
temperature catalytic oxidative combustion (ISO 20236:2018)
Wasserbeschaffenheit - Bestimmung des gesamten organischen Kohlenstoffs (TOC),

des gelösten organischen Kohlenstoffs (DOC), des gebundenen Stickstoffs (TNb) und

des gelösten gebundenen Stickstoffs (DNb) nach katalytischer oxidativer
Hochtemperaturverbrennung (ISO 20236:2018)

Qualité de l'eau - Dosage du carbone organique total (COT), carbone organique (COD),

azote lié total (TNb) et azote lié dissous (DNb) après combustion oxidatif catalytique à

haute temperature (ISO 20236:2018)
Ta slovenski standard je istoveten z: EN ISO 20236:2021
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
SIST EN ISO 20236:2022 en,fr,de

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

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SIST EN ISO 20236:2022
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SIST EN ISO 20236:2022
EN ISO 20236
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2021
EUROPÄISCHE NORM
ICS 13.060.50 Supersedes EN 12260:2003
English Version
Water quality - Determination of total organic carbon
(TOC), dissolved organic carbon (DOC), total bound
nitrogen (TNb) and dissolved bound nitrogen (DNb) after
high temperature catalytic oxidative combustion (ISO
20236:2018)

Qualité de l'eau - Dosage du carbone organique total Wasserbeschaffenheit - Bestimmung des gesamten

(COT), carbone organique (COD), azote lié total (TNb) organischen Kohlenstoffs (TOC), des gelösten

et azote lié dissous (DNb) après combustion oxidatif organischen Kohlenstoffs (DOC), des gebundenen

catalytique à haute temperature (ISO 20236:2018) Stickstoffs (TNb) und des gelösten gebundenen

Stickstoffs (DNb) nach katalytischer oxidativer
Hochtemperaturverbrennung (ISO 20236:2018)
This European Standard was approved by CEN on 15 November 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20236:2021 E

worldwide for CEN national Members.
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SIST EN ISO 20236:2022
EN ISO 20236:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

Endorsement notice ..................................................................................................................................................... 3

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SIST EN ISO 20236:2022
EN ISO 20236:2021 (E)
European foreword

The text of ISO 20236:2018 has been prepared by Technical Committee ISO/TC 147 "Water quality” of

the International Organization for Standardization (ISO) and has been taken over as EN ISO 20236:2021

by Technical Committee CEN/TC 230 “Water analysis” the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by May 2022, and conflicting national standards shall be

withdrawn at the latest by May 2022.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 12260:2003.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 20236:2018 has been approved by CEN as EN ISO 20236:2021 without any modification.

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SIST EN ISO 20236:2022
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SIST EN ISO 20236:2022
INTERNATIONAL ISO
STANDARD 20236
First edition
2018-09
Water quality — Determination of
total organic carbon (TOC), dissolved
organic carbon (DOC), total bound
nitrogen (TN ) and dissolved bound
nitrogen (DN ) after high temperature
catalytic oxidative combustion
Qualité de l'eau — Dosage du carbone organique total (COT),
carbone organique (COD), azote lié total (TN ) et azote lié dissous
(DN ) après combustion oxidatif catalytique à haute temperature
Reference number
ISO 20236:2018(E)
ISO 2018
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SIST EN ISO 20236:2022
ISO 20236:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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

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

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

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 20236:2022
ISO 20236:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

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

5 Interferences ............................................................................................................................................................................................................ 3

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

5.2 TOC or DOC ......... ........................................................................................................................................................................................ 3

5.3 TN or DN .................................................................................................................................................................................................. 4

b b

6 Reagents ........................................................................................................................................................................................................................ 4

7 Apparatus ..................................................................................................................................................................................................................... 6

8 Quality requirements for the analytical system .................................................................................................................. 8

8.1 System check ............................................................................................................................................................................................. 8

8.2 Recovery and variation of replicate determinations for particle processing control

for TOC and TN .....................................................................................................................................................................................8

9 Sampling and sample preparation .................................................................................................................................................... 8

10 Procedure..................................................................................................................................................................................................................... 9

10.1 General ........................................................................................................................................................................................................... 9

10.2 Calibration .................................................................................................................................................................................................. 9

10.3 Validity check of the calibration function ........................................................................................................................ 9

10.4 Measurement ............................................................................................................................................................................................ 9

10.4.1 General...................................................................................................................................................................................... 9

10.4.2 Determination .................................................................................................................................................................10

11 Evaluation .................................................................................................................................................................................................................11

12 Expression of results .....................................................................................................................................................................................11

13 Test report ................................................................................................................................................................................................................11

Annex A (normative) Determination of TOC and TIC applying the difference method ................................12

Annex B (informative) Performance data for TOC or DOC and TN or DN ...............................................................15

b b

Annex C (informative) Alternative detection techniques for TN and DN ...............................................................17

b b

Bibliography .............................................................................................................................................................................................................................18

© ISO 2018 – All rights reserved iii
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SIST EN ISO 20236:2022
ISO 20236:2018(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 147, Water quality, Subcommittee SC 2,

Physical, chemical and biochemical methods.

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.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 20236:2022
ISO 20236:2018(E)
Introduction

Total organic carbon (TOC), dissolved organic carbon (DOC), total bound nitrogen (TN ) and dissolved

bound nitrogen (DN ) are an analytical convention, the respective result of which is a parameter used

for water quality control purposes. These parameters represent the sum of organically bound carbon

as well as the sum of inorganic and organic nitrogen (but not nitrogen gas), which can be dissolved in

water or bonded to dissolved or suspended matter under specified conditions and, if the sample is not

filtered, includes that associated with suspended matter. It does not give information on the nature of

the substances.

Details of an interlaboratory trial on the performance data for TOC or DOC and TN or DN are given in

b b
Annex B.
© ISO 2018 – All rights reserved v
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SIST EN ISO 20236:2022
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SIST EN ISO 20236:2022
INTERNATIONAL STANDARD ISO 20236:2018(E)
Water quality — Determination of total organic carbon
(TOC), dissolved organic carbon (DOC), total bound
nitrogen (TN ) and dissolved bound nitrogen (DN ) after
b b
high temperature catalytic oxidative combustion

WARNING — Persons using this document should be familiar with normal laboratory practice.

This document does not purport to address all of the safety problems, if any, associated with its

use. It is the responsibility of the user to establish appropriate safety and health practices.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies a method for the determination of total organic carbon (TOC), dissolved

organic carbon (DOC), total bound nitrogen (TN ) and dissolved bound nitrogen (DN ) in the form of

b b

free ammonia, ammonium, nitrite, nitrate and organic compounds capable of conversion to nitrogen

oxides under the conditions described. The procedure is carried out instrumentally.

NOTE Generally the method can be applied for the determination of total carbon (TC) and total inorganic

carbon (TIC), see Annex A.

The method is applicable to water samples (e.g. drinking water, raw water, ground water, surface water,

sea water, waste water, leachates).

The method allows a determination of TOC and DOC ≥ 1 mg/l and TN and DN ≥ 1 mg/l. The upper

b b

working range is restricted by instrument-dependent conditions (e.g. injection volume). Higher

concentrations can be determined after appropriate dilution of the sample.

For samples containing volatile organic compounds (e.g. industrial waste water), the difference method

is used, see Annex A.

Cyanide, cyanate and particles of elemental carbon (soot), when present in the sample, can be

determined together with the organic carbon.

The method is not appropriate for the determination of volatile, or purgeable, organic carbon under the

conditions described by this method.
Dissolved nitrogen gas (N ) is not determined.
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 8466-1, Water quality — Calibration and evaluation of analytical methods and estimation of

performance characteristics — Part 1: Statistical evaluation of the linear calibration function

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2018 – All rights reserved 1
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SIST EN ISO 20236:2022
ISO 20236:2018(E)

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 https: //www .electropedia .org/
3.1
total carbon

sum of organically and inorganically bound carbon present in water, including elemental carbon

3.2
total inorganic carbon
TIC

sum of inorganic carbon present in water sample measured under the conditions of this method

Note 1 to entry: TIC is measured as CO originating only from carbonates, hydrogen carbonates and dissolved

carbon dioxide.
3.3
total organic carbon
TOC

sum of organically bound carbon present in water, bonded to dissolved or suspended matter, including

cyanate, thiocyanate and elemental carbon measured under the conditions of this method

Note 1 to entry: Volatile organic carbon cannot be guaranteed to be determined by the method.

Note 2 to entry: Generally, TOC includes organic compounds in water that cannot be purged under the conditions

of this method, also known as non-purgeable organic carbon (NPOC).
3.4
dissolved organic carbon
DOC

sum of organically bound carbon present in water originating from compounds passing through a

membrane filter of 0,45 µm pore size, including cyanate and thiocyanate measured under the conditions

of this method
3.5
total bound nitrogen

sum of organically bound and inorganically bound nitrogen present in water or suspended matter

measured under the conditions of this method
3.6
dissolved bound nitrogen

sum of organically and inorganically bound nitrogen present in water originating from compounds

passing through a 0,45 µm membrane filter measured under the conditions of this method

4 Principle

Thermal catalytic combustion of the sample containing organic carbon, and inorganic and organic

nitrogen in an oxygen-containing atmosphere at ≥ 680 °C for TOC or DOC and ≥ 720 °C for TN or DN

b b
determinations.

The TOC or DOC determination is carried out in accordance with the direct measurement method.

2 © ISO 2018 – All rights reserved
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SIST EN ISO 20236:2022
ISO 20236:2018(E)

Prior to combustion, remove inorganic carbon by acidification and purging with a carrier gas (6.7).

NOTE Platinum and cerium(IV), for example, can be used as catalyst material for combustion. The catalyst

serves to accelerate the oxidation process of carbon containing water constituents in excess of oxygen to

produce the required carbon dioxide gas for the detection process. Depending on combustion temperature

and temperatures in the combustion zone, different catalysts can be used, e.g. metals or metal oxides for

temperatures > 680 °C or sintered Alumina for temperatures around 1 200 °C, according to verifications of

different suppliers.

Oxidation of organic carbon (TOC, DOC) with oxygen or synthetic air to carbon dioxide. Detection by

means of infrared spectrometry (IR). Combustion of inorganic and organic nitrogen with oxygen or

synthetic air and conversion to nitric oxide.

Reaction with ozone giving electronically excited nitrogen oxides. Detection by means of

chemiluminescence (CLD) (see Annex C for alternative detection).

This document can be applied for the determination of TOC or DOC and TN or DN separately or for

b b

simultaneous TOC or DOC and TN or DN determinations, for example connecting the IR detector with

b b
a CLD in series.

Quality control is necessary to check the validity of the calibration function (see 10.3). Replicate

determinations can be necessary. The method of standard addition can be required if matrix

interferences are expected (see 5.3 and 10.4.2.1).
5 Interferences
5.1 General

Interferences with the determination of TOC or DOC and TN or DN can arise from memory effects.

b b
Replicate injections are necessary (see 10.4.1).

Detergents, oils and fats can influence the surface tension of the sample, causing erroneous data. A

dilution of the sample can reduce such risk.

Samples with extreme pH values, highly buffered samples and samples with high salt contents can

cause interference. Seek advice from the manufacturer to solve these interferences.

Suspended material can lead to a loss of quality of the analytical result. If a homogenized sample

containing suspended material produces results obtained from replicate measurements that deviate by

more than 10 %, an accurate TOC or TN result cannot be obtained on the sample.
5.2 TOC or DOC

Inorganic carbon (e.g. CO or ions of carbonic acid) present in the sample interferes with the

determination of TOC or DOC. Inorganic carbon is removed by acidification and purging with a gas

that is free from CO and organic compounds prior to the TOC or DOC determination (see 10.4.2.2 and

10.4.2.3).

NOTE 1 Alternatively, the differential method determining the TC and TIC separately can be applied

(see Annex A). The TOC can be calculated by subtracting TIC from the TC. This calculation leads to correct results

only as long as carbon monoxide, cyanide, cyanate and thiocyanate are present with negligible concentrations.

NOTE 2 Purgeable organic carbon substances, such as benzene, toluene, cyclohexane and chloroform,

can partly escape upon stripping (see 10.4.2.2 and 10.4.2.3). In the presence of these substances, the TOC

concentration can be determined separately, for example by applying the differential method (see Annex A).

© ISO 2018 – All rights reserved 3
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SIST EN ISO 20236:2022
ISO 20236:2018(E)
5.3 TN or DN
b b

High loads of dissolved or total organic carbon (DOC or TOC) can lead to poor recovery of TN or DN .

b b

Suspected problems can be identified by determining nitrogen before and after suitable dilution, or by

using standard addition techniques.

Not all organic nitrogen compounds are quantitatively converted to nitrogen oxide by the combustion

procedure described, and consequently to nitrogen dioxide by the reaction with ozone. Poor recoveries

can occur with compounds containing either double- or triple-bonded nitrogen atoms. The use of

a calibration function calculated in accordance with 10.2 and applying a nitrogen mixed standard

solution II (6.9.3.4) can result in a negative TN bias for ammonium-N determinations (e.g. ammonium

sulfate solution) and a positive bias for nitrate-N determinations (e.g. potassium nitrate solution).

6 Reagents
Use reagents of pro analysis grade, if available.

Dry all solid reagents for at least 1 h at (105 ± 5) °C. Store the dried solid in a desiccator before weighing.

NOTE It is not necessary to dry cellulose before usage.

Prepare alternative concentrations and volumes of solutions as described hereafter, if necessary.

Alternatively, use commercially available stock solutions of the required concentration.

When applying the simultaneous determination of TN and TOC, an appropriate mixture of the

1 000 mg/l TOC and TN stock solutions (6.8.2 and 6.9.3.3) for the preparation of standard and

calibration solutions can be used.
6.1 Water.

The contents of carbon and bound nitrogen in water used for the preparation of samples and solutions

shall be sufficiently low to be negligible in comparison with the lowest TOC and TN concentration to

be determined.
6.2 Sulfuric acid, ρ = 1,84 g/ml.
6.3 Hydrochloric acid, ω(HCl) = 32 %.
6.4 Nicotinic acid, C H NO , > 99,5 %.
6 5 2
6.5 TOC and TN stock solution for system check.

Place 8,793 g of nicotinic acid (6.4) in a 1 000 ml volumetric flask. Dissolve and dilute to volume with

water (6.1).
The solution contains 5 147 mg/l of carbon and 1 000 mg/l of nitrogen.
The solution is stable for six months if stored at (3 ± 2) °C.
6.6 Blank solution.
Fill a 100 ml volumetric flask with water (6.1).

6.7 Gases or synthetic air, free from impurities with influence of the determinant (e.g. carbon dioxide,

organic carbon, nitrogen compounds).

Use gases in accordance with the manufacturer’s specifications, for example oxygen, 99,7 % volume

fraction.
4 © ISO 2018 – All rights reserved
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SIST EN ISO 20236:2022
ISO 20236:2018(E)
6.8 Reagents for the TOC or DOC determination.
6.8.1 Potassium hydrogen phthalate, C H KO .
8 5 4
6.8.2 Potassium hydrogen phthalate stock solution, ρ(C) = 1 000 mg/l.

Place 2,125 g of potassium hydrogen phthalate (6.8.1) in a 1 000 ml volumetric flask. Dissolve and dilute

to volume with water (6.1).
The solution is stable for six months if stored at (3 ± 2) °C.
6.8.3 Potassium hydrogen phthalate standard solution, ρ(C) = 100 mg/l.

Pipette 100 ml of the potassium hydrogen phthalate stock standard solution (6.8.2) into a 1 000 ml

volumetric flask and dilute to volume with water (6.1).
The solution is stable for one month if stored at (3 ± 2) °C.
6.8.4 TOC and DOC calibration solutions.

Depending on the TOC or DOC concentration expected in the sample, use the potassium hydrogen

phthalate standard solution (6.8.3) to prepare five to ten calibration solutions distributed over the

expected working range as evenly as possible.
For example, proceed as follows for the range 1,0 mg/l C to 10 mg/l C.

Pipette the following volumes into a series of 100 ml volumetric flasks: 1,0 ml, 2,0 ml, 3,0 ml, 4,0 ml,

5,0 ml, 6,0 ml, 7,0 ml, 8,0 ml, 9,0 ml or 10,0 ml of the potassium hydrogen phthalate standard solution

(6.8.3) and dilute to volume with water (6.1).

The concentrations of carbon in these calibration solutions are: 1 mg/l, 2 mg/l, 3 mg/l, 4 mg/l, 5 mg/l,

6 mg/l, 7 mg/l, 8 mg/l, 9 mg/l or 10 mg/l, respectively.
Prepare the calibration solutions on the day of use.
6.8.5 Hydrochloric acid TIC stripping solution, c(HCl) = e.g. 3 mol/l.
6.8.6 Cellulose, (C H O ) , microcrystalline, of partic
...

SLOVENSKI STANDARD
oSIST prEN ISO 20236:2021
01-september-2021
Kakovost vode - Določevanje celotnega organskega ogljika (TOC), raztopljenega
organskega ogljika (DOC), celotnega vezanega dušika (TNb) in raztopljenega
vezanega dušika (DNb) po katalitskem sežigu pri visoki temperaturi (ISO
20236:2018)

Water quality - Determination of total organic carbon (TOC), dissolved organic carbon

(DOC), total bound nitrogen (TNb) and dissolved bound nitrogen (DNb) after high
temperature catalytic oxidative combustion (ISO 20236:2018)
Wasserbeschaffenheit - Bestimmung des gesamten organischen Kohlenstoffs (TOC),

des gelösten organischen Kohlenstoffs (DOC), des gebundenen Stickstoffs (TNb) und

des gelösten gebundenen Stickstoffs (DNb) nach katalytischer oxidativer
Hochtemperaturverbrennung (ISO 20236:2018)

Qualité de l'eau - Dosage du carbone organique total (COT), carbone organique (COD),

azote lié total (TNb) et azote lié dissous (DNb) après combustion oxidatif catalytique à

haute temperature (ISO 20236:2018)
Ta slovenski standard je istoveten z: prEN ISO 20236
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
oSIST prEN ISO 20236:2021 en,fr,de

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

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oSIST prEN ISO 20236:2021
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oSIST prEN ISO 20236:2021
INTERNATIONAL ISO
STANDARD 20236
First edition
2018-09
Water quality — Determination of
total organic carbon (TOC), dissolved
organic carbon (DOC), total bound
nitrogen (TN ) and dissolved bound
nitrogen (DN ) after high temperature
catalytic oxidative combustion
Qualité de l'eau — Dosage du carbone organique total (COT),
carbone organique (COD), azote lié total (TN ) et azote lié dissous
(DN ) après combustion oxidatif catalytique à haute temperature
Reference number
ISO 20236:2018(E)
ISO 2018
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oSIST prEN ISO 20236:2021
ISO 20236:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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

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Published in Switzerland
ii © ISO 2018 – All rights reserved
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oSIST prEN ISO 20236:2021
ISO 20236:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

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

5 Interferences ............................................................................................................................................................................................................ 3

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

5.2 TOC or DOC ......... ........................................................................................................................................................................................ 3

5.3 TN or DN .................................................................................................................................................................................................. 4

b b

6 Reagents ........................................................................................................................................................................................................................ 4

7 Apparatus ..................................................................................................................................................................................................................... 6

8 Quality requirements for the analytical system .................................................................................................................. 8

8.1 System check ............................................................................................................................................................................................. 8

8.2 Recovery and variation of replicate determinations for particle processing control

for TOC and TN .....................................................................................................................................................................................8

9 Sampling and sample preparation .................................................................................................................................................... 8

10 Procedure..................................................................................................................................................................................................................... 9

10.1 General ........................................................................................................................................................................................................... 9

10.2 Calibration .................................................................................................................................................................................................. 9

10.3 Validity check of the calibration function ........................................................................................................................ 9

10.4 Measurement ............................................................................................................................................................................................ 9

10.4.1 General...................................................................................................................................................................................... 9

10.4.2 Determination .................................................................................................................................................................10

11 Evaluation .................................................................................................................................................................................................................11

12 Expression of results .....................................................................................................................................................................................11

13 Test report ................................................................................................................................................................................................................11

Annex A (normative) Determination of TOC and TIC applying the difference method ................................12

Annex B (informative) Performance data for TOC or DOC and TN or DN ...............................................................15

b b

Annex C (informative) Alternative detection techniques for TN and DN ...............................................................17

b b

Bibliography .............................................................................................................................................................................................................................18

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oSIST prEN ISO 20236:2021
ISO 20236:2018(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 147, Water quality, Subcommittee SC 2,

Physical, chemical and biochemical methods.

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.
iv © ISO 2018 – All rights reserved
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oSIST prEN ISO 20236:2021
ISO 20236:2018(E)
Introduction

Total organic carbon (TOC), dissolved organic carbon (DOC), total bound nitrogen (TN ) and dissolved

bound nitrogen (DN ) are an analytical convention, the respective result of which is a parameter used

for water quality control purposes. These parameters represent the sum of organically bound carbon

as well as the sum of inorganic and organic nitrogen (but not nitrogen gas), which can be dissolved in

water or bonded to dissolved or suspended matter under specified conditions and, if the sample is not

filtered, includes that associated with suspended matter. It does not give information on the nature of

the substances.

Details of an interlaboratory trial on the performance data for TOC or DOC and TN or DN are given in

b b
Annex B.
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oSIST prEN ISO 20236:2021
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oSIST prEN ISO 20236:2021
INTERNATIONAL STANDARD ISO 20236:2018(E)
Water quality — Determination of total organic carbon
(TOC), dissolved organic carbon (DOC), total bound
nitrogen (TN ) and dissolved bound nitrogen (DN ) after
b b
high temperature catalytic oxidative combustion

WARNING — Persons using this document should be familiar with normal laboratory practice.

This document does not purport to address all of the safety problems, if any, associated with its

use. It is the responsibility of the user to establish appropriate safety and health practices.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this document

be carried out by suitably qualified staff.
1 Scope

This document specifies a method for the determination of total organic carbon (TOC), dissolved

organic carbon (DOC), total bound nitrogen (TN ) and dissolved bound nitrogen (DN ) in the form of

b b

free ammonia, ammonium, nitrite, nitrate and organic compounds capable of conversion to nitrogen

oxides under the conditions described. The procedure is carried out instrumentally.

NOTE Generally the method can be applied for the determination of total carbon (TC) and total inorganic

carbon (TIC), see Annex A.

The method is applicable to water samples (e.g. drinking water, raw water, ground water, surface water,

sea water, waste water, leachates).

The method allows a determination of TOC and DOC ≥ 1 mg/l and TN and DN ≥ 1 mg/l. The upper

b b

working range is restricted by instrument-dependent conditions (e.g. injection volume). Higher

concentrations can be determined after appropriate dilution of the sample.

For samples containing volatile organic compounds (e.g. industrial waste water), the difference method

is used, see Annex A.

Cyanide, cyanate and particles of elemental carbon (soot), when present in the sample, can be

determined together with the organic carbon.

The method is not appropriate for the determination of volatile, or purgeable, organic carbon under the

conditions described by this method.
Dissolved nitrogen gas (N ) is not determined.
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 8466-1, Water quality — Calibration and evaluation of analytical methods and estimation of

performance characteristics — Part 1: Statistical evaluation of the linear calibration function

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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oSIST prEN ISO 20236:2021
ISO 20236:2018(E)

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 https: //www .electropedia .org/
3.1
total carbon

sum of organically and inorganically bound carbon present in water, including elemental carbon

3.2
total inorganic carbon
TIC

sum of inorganic carbon present in water sample measured under the conditions of this method

Note 1 to entry: TIC is measured as CO originating only from carbonates, hydrogen carbonates and dissolved

carbon dioxide.
3.3
total organic carbon
TOC

sum of organically bound carbon present in water, bonded to dissolved or suspended matter, including

cyanate, thiocyanate and elemental carbon measured under the conditions of this method

Note 1 to entry: Volatile organic carbon cannot be guaranteed to be determined by the method.

Note 2 to entry: Generally, TOC includes organic compounds in water that cannot be purged under the conditions

of this method, also known as non-purgeable organic carbon (NPOC).
3.4
dissolved organic carbon
DOC

sum of organically bound carbon present in water originating from compounds passing through a

membrane filter of 0,45 µm pore size, including cyanate and thiocyanate measured under the conditions

of this method
3.5
total bound nitrogen

sum of organically bound and inorganically bound nitrogen present in water or suspended matter

measured under the conditions of this method
3.6
dissolved bound nitrogen

sum of organically and inorganically bound nitrogen present in water originating from compounds

passing through a 0,45 µm membrane filter measured under the conditions of this method

4 Principle

Thermal catalytic combustion of the sample containing organic carbon, and inorganic and organic

nitrogen in an oxygen-containing atmosphere at ≥ 680 °C for TOC or DOC and ≥ 720 °C for TN or DN

b b
determinations.

The TOC or DOC determination is carried out in accordance with the direct measurement method.

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Prior to combustion, remove inorganic carbon by acidification and purging with a carrier gas (6.7).

NOTE Platinum and cerium(IV), for example, can be used as catalyst material for combustion. The catalyst

serves to accelerate the oxidation process of carbon containing water constituents in excess of oxygen to

produce the required carbon dioxide gas for the detection process. Depending on combustion temperature

and temperatures in the combustion zone, different catalysts can be used, e.g. metals or metal oxides for

temperatures > 680 °C or sintered Alumina for temperatures around 1 200 °C, according to verifications of

different suppliers.

Oxidation of organic carbon (TOC, DOC) with oxygen or synthetic air to carbon dioxide. Detection by

means of infrared spectrometry (IR). Combustion of inorganic and organic nitrogen with oxygen or

synthetic air and conversion to nitric oxide.

Reaction with ozone giving electronically excited nitrogen oxides. Detection by means of

chemiluminescence (CLD) (see Annex C for alternative detection).

This document can be applied for the determination of TOC or DOC and TN or DN separately or for

b b

simultaneous TOC or DOC and TN or DN determinations, for example connecting the IR detector with

b b
a CLD in series.

Quality control is necessary to check the validity of the calibration function (see 10.3). Replicate

determinations can be necessary. The method of standard addition can be required if matrix

interferences are expected (see 5.3 and 10.4.2.1).
5 Interferences
5.1 General

Interferences with the determination of TOC or DOC and TN or DN can arise from memory effects.

b b
Replicate injections are necessary (see 10.4.1).

Detergents, oils and fats can influence the surface tension of the sample, causing erroneous data. A

dilution of the sample can reduce such risk.

Samples with extreme pH values, highly buffered samples and samples with high salt contents can

cause interference. Seek advice from the manufacturer to solve these interferences.

Suspended material can lead to a loss of quality of the analytical result. If a homogenized sample

containing suspended material produces results obtained from replicate measurements that deviate by

more than 10 %, an accurate TOC or TN result cannot be obtained on the sample.
5.2 TOC or DOC

Inorganic carbon (e.g. CO or ions of carbonic acid) present in the sample interferes with the

determination of TOC or DOC. Inorganic carbon is removed by acidification and purging with a gas

that is free from CO and organic compounds prior to the TOC or DOC determination (see 10.4.2.2 and

10.4.2.3).

NOTE 1 Alternatively, the differential method determining the TC and TIC separately can be applied

(see Annex A). The TOC can be calculated by subtracting TIC from the TC. This calculation leads to correct results

only as long as carbon monoxide, cyanide, cyanate and thiocyanate are present with negligible concentrations.

NOTE 2 Purgeable organic carbon substances, such as benzene, toluene, cyclohexane and chloroform,

can partly escape upon stripping (see 10.4.2.2 and 10.4.2.3). In the presence of these substances, the TOC

concentration can be determined separately, for example by applying the differential method (see Annex A).

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5.3 TN or DN
b b

High loads of dissolved or total organic carbon (DOC or TOC) can lead to poor recovery of TN or DN .

b b

Suspected problems can be identified by determining nitrogen before and after suitable dilution, or by

using standard addition techniques.

Not all organic nitrogen compounds are quantitatively converted to nitrogen oxide by the combustion

procedure described, and consequently to nitrogen dioxide by the reaction with ozone. Poor recoveries

can occur with compounds containing either double- or triple-bonded nitrogen atoms. The use of

a calibration function calculated in accordance with 10.2 and applying a nitrogen mixed standard

solution II (6.9.3.4) can result in a negative TN bias for ammonium-N determinations (e.g. ammonium

sulfate solution) and a positive bias for nitrate-N determinations (e.g. potassium nitrate solution).

6 Reagents
Use reagents of pro analysis grade, if available.

Dry all solid reagents for at least 1 h at (105 ± 5) °C. Store the dried solid in a desiccator before weighing.

NOTE It is not necessary to dry cellulose before usage.

Prepare alternative concentrations and volumes of solutions as described hereafter, if necessary.

Alternatively, use commercially available stock solutions of the required concentration.

When applying the simultaneous determination of TN and TOC, an appropriate mixture of the

1 000 mg/l TOC and TN stock solutions (6.8.2 and 6.9.3.3) for the preparation of standard and

calibration solutions can be used.
6.1 Water.

The contents of carbon and bound nitrogen in water used for the preparation of samples and solutions

shall be sufficiently low to be negligible in comparison with the lowest TOC and TN concentration to

be determined.
6.2 Sulfuric acid, ρ = 1,84 g/ml.
6.3 Hydrochloric acid, ω(HCl) = 32 %.
6.4 Nicotinic acid, C H NO , > 99,5 %.
6 5 2
6.5 TOC and TN stock solution for system check.

Place 8,793 g of nicotinic acid (6.4) in a 1 000 ml volumetric flask. Dissolve and dilute to volume with

water (6.1).
The solution contains 5 147 mg/l of carbon and 1 000 mg/l of nitrogen.
The solution is stable for six months if stored at (3 ± 2) °C.
6.6 Blank solution.
Fill a 100 ml volumetric flask with water (6.1).

6.7 Gases or synthetic air, free from impurities with influence of the determinant (e.g. carbon dioxide,

organic carbon, nitrogen compounds).

Use gases in accordance with the manufacturer’s specifications, for example oxygen, 99,7 % volume

fraction.
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6.8 Reagents for the TOC or DOC determination.
6.8.1 Potassium hydrogen phthalate, C H KO .
8 5 4
6.8.2 Potassium hydrogen phthalate stock solution, ρ(C) = 1 000 mg/l.

Place 2,125 g of potassium hydrogen phthalate (6.8.1) in a 1 000 ml volumetric flask. Dissolve and dilute

to volume with water (6.1).
The solution is stable for six months if stored at (3 ± 2) °C.
6.8.3 Potassium hydrogen phthalate standard solution, ρ(C) = 100 mg/l.

Pipette 100 ml of the potassium hydrogen phthalate stock standard solution (6.8.2) into a 1 000 ml

volumetric flask and dilute to volume with water (6.1).
The solution is stable for one month if stored at (3 ± 2) °C.
6.8.4 TOC and DOC calibration solutions.

Depending on the TOC or DOC concentration expected in the sample, use the potassium hydrogen

phthalate standard solution (6.8.3) to prepare five to ten calibration solutions distributed over the

expected working range as evenly as possible.
For example, proceed as follows for the range 1,0 mg/l C to 10 mg/l C.

Pipette the following volumes into a series of 100 ml volumetric flasks: 1,0 ml, 2,0 ml, 3,0 ml, 4,0 ml,

5,0 ml, 6,0 ml, 7,0 ml, 8,0 ml, 9,0 ml or 10,0 ml of the potassium hydrogen phthalate standard solution

(6.8.3) and dilute to volume with water (6.1).

The concentrations of carbon in these calibration solutions are: 1 mg/l, 2 mg/l, 3 mg/l, 4 mg/l, 5 mg/l,

6 mg/l, 7 mg/l, 8 mg/l, 9 mg/l or 10 mg/l, respectively.
Prepare the calibration solutions on the day of use.
6.8.5 Hydrochloric acid TIC stripping solution, c(HCl) = e.g. 3 mol/l.

6.8.6 Cellulose, (C H O ) , microcrystalline, of particle size ranging from 0,02 mm to 0,1 mm.

6 10 5 n

6.8.6.1 Cellulose test suspension for particle processing control, ρ(C) = 100 mg/l.

Place 225 mg of cellulose (6.8.6) in a 1 000 ml volumetric flask, moist with water (6.1), and dilute to

volume with water (6.1).
The mixture is stable for one month if stored at (3 ± 2) °C.

Homogenize the suspension with a magnetic stirrer until the suspension is homogeneous before use.

Ultrasonic treatment should not be used because it reduces the particle size.
6.9 Reagents for the TN and DN determination.
b b
6.9.1 Ammonium sulfate, (NH ) SO .
4 2 4
6.9.2 Potassium nitrate, KNO .
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ISO 20236:2018(E)
6.9.3 Nitrogen stock standard solutions.
6.9.3.1 Ammonium sulfate stock solution, ρ(N) = 1 000 mg/l.

Place 4,717 g of ammonium sulfate (6.9.1) in a 1 000 ml volumetric flask. Dissolve in 500 ml of water

(6.1) and dilute to volume with water (6.1).
The solution is stable for six months if stored at (3 ± 2) °C.
6.9.3.2 Potassium nitrate stock solution, ρ(N) = 1 000 mg/l.

Place 7,219 g of potassium nitrate (6.9.2) in a 1 000 ml volumetric flask. Dissolve and dilute to volume

with water (6.1).
The solution is stable for six months if stored at (3 ± 2) °C.
6.9.3.3 Nitrogen mixed standard solution I, ρ(N) = 1 000 mg/l.

Mix equal volumes of the solutions 6.9.3.1 and 6.9.3.2 to produce a nitrogen mixed standard solution.

The solution is stable for one month if stored at (3 ± 2) °C.
6.9.3.4 Nitrogen standard solution II, ρ(N) = 100 mg/l.

Pipette 100 ml of nitrogen mixed standard solution I (6.9.3.3) into a 1 000 ml volumetric flask, and

dilute to volume with water (6.1).
The solution is stable for one month if stored at (3 ± 2) °C.
6.9.4 TN and DN calibration solutions.
b b

Depending on the nitrogen concentration expected in the sample, use the nitrogen standard solution II

(6.9.3.4) to prepare five to ten calibration solutions distributed over the expected working range as

evenly as possible.
For example, proceed as follows for the range 1,0 mg/l to 10 mg/l N.

Pipette the following volumes into a series of 100 ml volumetric flasks: 1,0 ml, 2,0 ml, 3,0 ml, 4,0 ml,

5,0 ml, 6,0 ml, 7,0 ml, 8,0 ml, 9,0 ml or 10,0 ml of the nitrogen mixed standard solution II (6.9.3.4) and

dilute to volume with water (6.1).

The concentrations of nitrogen in these calibration solutions are: 1 mg/l, 2 mg/l, 3 mg/l, 4 mg/l, 5 mg/l,

6 mg/l, 7 mg/l, 8 mg/l, 9 mg/l or 10 mg/l, respectively.
Prepare the calibration solutions on the day of use.
7 Apparatus
The usual laboratory apparatus and, in particular, the following.

7.1 Homogenization and particle size reducing device, for the homogenization of dispersed matter,

for example a suitable ultrasonic apparatus or a rotor-stator homogenizer (see Clause 9), if needed.

NOTE An ultrasonic device is suitable for the homogenization of samples, but it is not suitable for the

homogenization of the cellulose test suspension (6.8.6.1) for particle processing control.

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7.2 High temperature combustion system, see Figure 1, conforming to the quality requirements

given in Clause 8.

When measuring water samples containing particulate material, the instrument shall be capable of

injecting the particulate material.

NOTE Users applying a system for the simultaneous determination of TOC and TN can check for particle

procession using the TOC cellulose test suspension (6.8.6.1). No recommendation can be given for a suitable TN

test suspension.
In general, it shall consist of the following components.
7.2.1 Sample injection device, for automated or manual operation.

The use of an autosampler shall include a device to keep heterogeneous samples in a homogenous state

(e.g. magnetic stirrer) before injection.
7.2.2 Reaction vessel

Oven, heatable to at least to 680 °C for TOC or DOC and to 720 °C for TN or DN determinations.

b b
7.2.3 Detector.
7.2.3.1 IR detector for TOC or DOC.
7.2.3.2 Chemiluminescence detector (CLD) for TN or DN .
b b
NOTE See Annex C for alternative detectors.

7.2.4 Recording device, e.g. PC with software for data acquisition and evaluation.

Figure 1 — Examples for high temperature combustion system configurations with detectors

for the determination of A: TOC or DOC, B: DN or TN and C: TOC or DOC and DN and TN

b b b b
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8 Quality requirements for the analyt
...

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