ISO 8245:1987

Water quality — Guidelines for the determination of total organic carbon (TOC)

Qualité de l'eau — Guide pour le dosage du carbone organique total (COT)

Kakovost vode - Navodila za določanje skupnega organskega ogljika (TOC)

General Information

• Status: Withdrawn
• Publication Date: 17-Jun-1987
• Withdrawal Date: 17-Jun-1987
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Drafting Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 04-Mar-1999
• Ref Project: SIST ISO 8245:1996 - Water quality -- Guidelines for the determination of total organic carbon (TOC)

Relations

• Revised: ISO 8245:1999 - Water quality — Guidelines for the determination of total organic carbon (TOC) and dissolved organic carbon (DOC)
• Effective Date: 15-Apr-2008

Standards Content (Sample)

IS0
INTERNATIONAL STANDARD
8245
First edition
1987-06-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXflYHAPOflHAR OPrAHM3AuMFi il0 CTAHflAPTM3AL(MM
\
Water quality - Guidelines for the determination of
total organic carbon (TOC)
Qualité de l’eau - Guide pour le dosage du carbone organique total (COT)
Reference number
IS0 8245 : 1987 (E)

---------------------- Page: 1 ----------------------
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
(IS0 member bodies). The work of preparing International
national standards bodies
Standards is normally carried out through IS0 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, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard IS0 8145 was prepared by Technical Committee ISO/TC 147,
Water quality.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
O International Organization for Standardization, 1987 O
Printed in Switzerland

---------------------- Page: 2 ----------------------
IS0 8245 : 1987 (E)
INTERNATIONAL STANDARD
Water quality - Guidelines for the determination of
total organic carbon (TOC)
O Introduction 2 Reference
Total organic carbon (TOC) is a measure of the carbon content
IS0 5667-3, Water quality - Sampfing - Part 3: Guidance on
e
of dissolved and undissolved organic matter present in the the preservation and handling of samples.
water. It does not give information about the nature of the
organic substance. Inorganic carbon must be eliminated before
analysis or determined together with the TOC and subsequent-
3 Definitions
ly subtracted. The method is instrumental and the selection of
the analyser should take into consideration the carbon content
For the purpose of this International Standard the following
of the samples to be analysed. The carbon content of organic
definitions apply.
substances may vary widely.
3.1 total carbon (TC): The quantity of carbon present in
water in the form of organic, inorganic and elemental carbon.
1 Scope and field of application
3.2 total inorganic carbon (TIC) : The quantity of carbon
This International Standard gives guidelines for the measure-
present in water in the form of elemental carbon, total carbon
It covers
ment of TOC concentrations in all kinds of water.
dioxide, carbon monoxide, carbides, cyanates, cyanides and
definitions, interferences, reagents and pretreatment of water
thiocyanates.
samples containing 0,l to 1 O00 mg/I organic carbon. Higher
concentrations may be determined after appropriate dilution.
Under certain circumstances it may be necessary to pretreat the
3.3 total organic carbon (TOC): The quantity of carbon
sample, for example by the separation of larger particles con-
present in water in that organic matter which is dissolved or
tained in the water in order to avoid clogging of the apparatus.
suspended in the water.
This International Standard does not deal with the instrumental
(.
3.4 dissolved organic carbon (DOC) : The quantity of car-
side of the determination.
bon present in water in that organic matter which passes a
filtration step through a membrane filter of pore size 0.45 pm.
In addition to organic carbon, the sample may contain carbon
dioxide or ions from carbonic acid. Prior to the TOC determi-
nation, this inorganic carbon must be removed by purging the
acidified sample with gas free from CO2 and organic com- 4 Principle
pounds. Alternatively, both total carbon (TC) and total carbon
Oxidation by combustion, addition of suitable oxidant, or ultra-
dioxide may be determined and the organic carbon content
violet irradiation, of organic carbon in water to carbon dioxide.
(TOC) calculated by subtracting the total carbon dioxide from
the TC. This method is most suitable for samples in which the
The application of the ultra-violet method with only oxygen as
total carbon dioxide is less than the TOC.
an oxidant is restricted to unpolluted waters free from par-
ticulate matter. Inorganic carbon is eliminated through acidifi-
Volatile organic substances such as benzene, toluene,
cation and purging or is determined separately.
cyclohexane, and chloroform may escape during stripping of
CO2 The TOC of these substances must therefore be deter-
The carbon dioxide formed by oxidation may be determined
mined separately or the difference method may be applied.
either directly or after reduction to methane (CHS.
Particles of elemental carbon (soot), carbide, cyanides,
Among others, the following principles for the ultimate deter-
cyanates and isocyanates when present are determined
together with the organic carbon. mination of CO2 are applied : infra-red spectrometry, titration
(preferably in non-aqueous solution), thermal conductivity
NOTE - Bibliographic reference 11.2 gives a comparison of the oxi- (TCD), conductometry, coulometry, CO~sensitive electrodes
dation methods. TOC levels of different types of water are indicated. and, after reduction of the CO2 to CH4, flame ionization [FID).

---------------------- Page: 3 ----------------------
IS0 8245 : 1987 (E)
5.4 Further reagents
5 Reagents
Use only reagents of recognized analytical grade and only
5.4.1 The reagents 5.1 and 5.2 may be replaced by other sol-
distilled water or water of equivalent purity. In this International
utions of stable compounds as long as they meet the re-
Standard, only those chemicals are mentioned that are used in
quirements of titrimetric substances.
most TOC methods. Further chemicals may be used, and, if
necessary, pretreated, according to the manufacturer's instruc-
5.4.2 Non-volatile acid for expulsion of carbon dioxide, for
tions.
example phosphoric acid, ciH3P04) = 0,5 mol/l.
The TOC of the water used for dilutions and for preparation of
the calibration standards shall be negligible in comparison to
5.5 Gases
the TOC of the sample.
Air, nitrogen, oxygen, free from carbon dioxide and organic im-
The method for water pretreatment depends on the concen-
purities.
tration range to be measured. The pretreatment methods to be
used in accordance with the TOC of the sample are given in
1.
table
6 Apparatus
NOTE - Water with a TOC content <0,5 mg/l cannot be stored.
Usual laboratory apparatus and
6.1 Apparatus for TOC determination.
5.1 Potassium hydrogen phthalate stock solution,
O
@(organic C) = 1 O00 mg/l.
6.2 Homogenization device, for example ultrasonic instru-
Dissolve in a 1 O00 ml one-mark volumetric flask 2,125 g of
ment or magnetic stirrer with sufficient efficiency for
potassium hydrogen phthalate (C8H5K04) (dried at a tempera-
homogenization of dispersed matter.
ture not exeeding 120 OC for 2 h), in about 700 ml of water and
dilute to the mark with water.
7 Sampling and samples
This solution is stable for about 2 months, if stored in a tightly
stoppered bottle in a refrigerator.
7.1 Sampling
5.2 Potassium hydrogen phthalate, standard solution, See also IS0 5667-3.
@(organic C) = 100 mg/l.
When sampling, ensure that representative samples are col-
Pipette 100 ml of the potassium hydrogen phthalate stock sol- lected (this is especially essential when undissolved substances
ution (5.1) into a 1 O00 ml one-mark volumetric flask, dilute to are present) and be careful not to Contaminate the samples
the mark with water and mix. with organic substances. Water samples shall be withdrawn in
clean glass bottles which shall be filled completely. If storage is
This solution is stable for about one week, if stored in a tightly
necessary, store at 4 OC in a refrigerator. If bacteriological ac-
stoppered bottle in a refrigerator.
tivity is to be expected, the sample shall be acidified to pH 2
[e.g. with phosphoric acid (5.4.211 in case of storage.
5.3 Standar
...

SLOVENSKI STANDARD
SIST ISO 8245:1996
01-junij-1996
.DNRYRVWYRGH1DYRGLOD]DGRORþDQMHVNXSQHJDRUJDQVNHJDRJOMLND72&
Water quality -- Guidelines for the determination of total organic carbon (TOC)
Qualité de l'eau -- Guide pour le dosage du carbone organique total (COT)
Ta slovenski standard je istoveten z: ISO 8245:1987
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST ISO 8245:1996 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ISO 8245:1996

---------------------- Page: 2 ----------------------

SIST ISO 8245:1996
IS0
INTERNATIONAL STANDARD
8245
First edition
1987-06-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXflYHAPOflHAR OPrAHM3AuMFi il0 CTAHflAPTM3AL(MM
\
Water quality - Guidelines for the determination of
total organic carbon (TOC)
Qualité de l’eau - Guide pour le dosage du carbone organique total (COT)
Reference number
IS0 8245 : 1987 (E)

---------------------- Page: 3 ----------------------

SIST ISO 8245:1996
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
(IS0 member bodies). The work of preparing International
national standards bodies
Standards is normally carried out through IS0 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, govern-
mental and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council. They are approved in accordance with IS0 procedures requiring at
least 75 % approval by the member bodies voting.
International Standard IS0 8145 was prepared by Technical Committee ISO/TC 147,
Water quality.
Users should note that all International Standards undergo revision from time to time
and that any reference made herein to any other International Standard implies its
latest edition, unless otherwise stated.
O International Organization for Standardization, 1987 O
Printed in Switzerland

---------------------- Page: 4 ----------------------

SIST ISO 8245:1996
IS0 8245 : 1987 (E)
INTERNATIONAL STANDARD
Water quality - Guidelines for the determination of
total organic carbon (TOC)
O Introduction 2 Reference
Total organic carbon (TOC) is a measure of the carbon content
IS0 5667-3, Water quality - Sampfing - Part 3: Guidance on
e
of dissolved and undissolved organic matter present in the the preservation and handling of samples.
water. It does not give information about the nature of the
organic substance. Inorganic carbon must be eliminated before
analysis or determined together with the TOC and subsequent-
3 Definitions
ly subtracted. The method is instrumental and the selection of
the analyser should take into consideration the carbon content
For the purpose of this International Standard the following
of the samples to be analysed. The carbon content of organic
definitions apply.
substances may vary widely.
3.1 total carbon (TC): The quantity of carbon present in
water in the form of organic, inorganic and elemental carbon.
1 Scope and field of application
3.2 total inorganic carbon (TIC) : The quantity of carbon
This International Standard gives guidelines for the measure-
present in water in the form of elemental carbon, total carbon
It covers
ment of TOC concentrations in all kinds of water.
dioxide, carbon monoxide, carbides, cyanates, cyanides and
definitions, interferences, reagents and pretreatment of water
thiocyanates.
samples containing 0,l to 1 O00 mg/I organic carbon. Higher
concentrations may be determined after appropriate dilution.
Under certain circumstances it may be necessary to pretreat the
3.3 total organic carbon (TOC): The quantity of carbon
sample, for example by the separation of larger particles con-
present in water in that organic matter which is dissolved or
tained in the water in order to avoid clogging of the apparatus.
suspended in the water.
This International Standard does not deal with the instrumental
(.
3.4 dissolved organic carbon (DOC) : The quantity of car-
side of the determination.
bon present in water in that organic matter which passes a
filtration step through a membrane filter of pore size 0.45 pm.
In addition to organic carbon, the sample may contain carbon
dioxide or ions from carbonic acid. Prior to the TOC determi-
nation, this inorganic carbon must be removed by purging the
acidified sample with gas free from CO2 and organic com- 4 Principle
pounds. Alternatively, both total carbon (TC) and total carbon
Oxidation by combustion, addition of suitable oxidant, or ultra-
dioxide may be determined and the organic carbon content
violet irradiation, of organic carbon in water to carbon dioxide.
(TOC) calculated by subtracting the total carbon dioxide from
the TC. This method is most suitable for samples in which the
The application of the ultra-violet method with only oxygen as
total carbon dioxide is less than the TOC.
an oxidant is restricted to unpolluted waters free from par-
ticulate matter. Inorganic carbon is eliminated through acidifi-
Volatile organic substances such as benzene, toluene,
cation and purging or is determined separately.
cyclohexane, and chloroform may escape during stripping of
CO2 The TOC of these substances must therefore be deter-
The carbon dioxide formed by oxidation may be determined
mined separately or the difference method may be applied.
either directly or after reduction to methane (CHS.
Particles of elemental carbon (soot), carbide, cyanides,
Among others, the following principles for the ultimate deter-
cyanates and isocyanates when present are determined
together with the organic carbon. mination of CO2 are applied : infra-red spectrometry, titration
(preferably in non-aqueous solution), thermal conductivity
NOTE - Bibliographic reference 11.2 gives a comparison of the oxi- (TCD), conductometry, coulometry, CO~sensitive electrodes
dation methods. TOC levels of different types of water are indicated. and, after reduction of the CO2 to CH4, flame ionization [FID).

---------------------- Page: 5 ----------------------

SIST ISO 8245:1996
IS0 8245 : 1987 (E)
5.4 Further reagents
5 Reagents
Use only reagents of recognized analytical grade and only
5.4.1 The reagents 5.1 and 5.2 may be replaced by other sol-
distilled water or water of equivalent purity. In this International
utions of stable compounds as long as they meet the re-
Standard, only those chemicals are mentioned that are used in
quirements of titrimetric substances.
most TOC methods. Further chemicals may be used, and, if
necessary, pretreated, according to the manufacturer's instruc-
5.4.2 Non-volatile acid for expulsion of carbon dioxide, for
tions.
example phosphoric acid, ciH3P04) = 0,5 mol/l.
The TOC of the water used for dilutions and for preparation of
the calibration standards shall be negligible in comparison to
5.5 Gases
the TOC of the sample.
Air, nitrogen, oxygen, free from carbon dioxide and organic im-
The method for water pretreatment depends on the concen-
purities.
tration range to be measured. The pretreatment methods to be
used in accordance with the TOC of the sample are given in
1.
table
6 Apparatus
NOTE - Water with a TOC content <0,5 mg/l cannot be stored.
Usual laboratory apparatus and
6.1 Apparatus for TOC determination.
5.1 Potassium hydrogen phthalate stock solution,
O
@(organic C) = 1 O00 mg/l.
6.2 Homogenization device, for example ultrasonic instru-
Dissolve in a 1 O00 ml one-mark volumetric flask 2,125 g of
ment or magnetic stirrer with sufficient efficiency for
potassium hydrogen phthalate (C8H5K04) (dried at a tempera-
homogenization of dispersed matter.
ture not exeeding 120 OC for 2 h), in about 700 ml of water and
dilute to the mark with water.
7 Sampling and samples
This solution is stable for about 2 months, if stored in a tightly
stoppered bottle in a refrigerator.
7.1 Sampling
5.2 Potassium hydrogen phthalate, standard solution, See also IS0 5667-3.
@(organic C) = 100 mg/l.
When sampling, ensure that representative samples are col-
Pipette 100 ml of the potassium hydrogen phthalate stock sol- lected (this is especially essential when undissolved substances
ution (5.1) into a 1 O00 ml one-mark volumetric flask, dilute to are present) and be careful not to Contaminate the sam
...

IS0
8245
NORME INTERNATIONALE
Première édition
1987-06-1 5
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
ME>KL1YHAPOAHAR OPïAHM3Ai#lR Il0 CTAHC(APTM3AL(MM
Qualité de l'eau - Guide pour le dosage du carbone
organique total (COT)
Water quality - Guidelines for the determination of total organic carbon /TOC)
Numéro de rtférenc
IS0 8245 : 1987 (P)

---------------------- Page: 1 ----------------------
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale
d'organismes nationaux de normalisation (comités membres de I'ISO). L'élaboration
des Normes internationales est normalement confiée aux comités techniques de I'ISO.
Chaque comité membre intéressé par une étude a le droit de faire partie du comité
technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec I'ISO participent également aux travaux.
*
Les projets de Normes internationales adoptés par les comités techniques sont soumis
aux comités membres pour approbation, avant leur acceptation comme Normes inter-
nationales par le Conseil de I'ISO. Les Normes internationales sont approuvées confor-
mément aux procédures de 1'1S0 qui requièrent l'approbation de 75 % au moins des
comités membres votants.
La Norme internationate is0 824 a été élaborée par le comité technique ISO/TC 147,
Qualité de l'eau.
L'attention des utilisateurs est attirée sur le fait que toutes les Normes internationales
sont de temps en temps soumises à révision et que toute référence faite à une autre
Norme internationale dans le présent document implique qu'il s'agit, sauf indication
contraire, de la dernière édition.
O organisation internationale de normalisation, 1987 0
Imprimé en Suisse

---------------------- Page: 2 ----------------------
IS0 8245 : 1987 (F)
NORM€ INTERNATIONALE
Qualité de l'eau - Guide pour le dosage du carbone
organique total (COT)
O Introduction s'échappent pendant le stripping du CO2 Le COT de ces subs-
tances doit donc être déterminé séparément ou selon la
Le carbone organique total (COT) est une mesure de la teneur méthode différentielle.
en carbone des matières organiques, dissoutes et non dissou-
tes, présentes dans l'eau. II ne donne pas d'indication sur la
La présence éventuelle de particules de carbone élémentaire
nature de la substance organique. Le carbone inorganique doit (suie), de cyanates, de cyanures et d'isocyanates est détermi-
être éliminé avant analyse, ou être déterminé conjointement
née parallèlement au carbone organique.
avec le COT et retranché ultérieurement. La méthode est instru-
mentale et le choix d'un analyseur doit tenir compte de la NOTE - La référence bibliographique 11.2 donne une comparaison
teneur en carbone des échantillons à analyser. La teneur en car- des différentes méthodes d'oxydation. Cette référence indique égale-
ment les différents niveaux de COT pour différents types d'eaux.
bone des substances organiques peut varier dans une large
mesure.
2 Référence
1 Objet et domaine d'application
IS0 5667-3, Qualité de l'eau - Échantillonnage - Partie 3:
Guide général pour la conservation et la manipulation des
La présente Norme internationale donne des conseils pour le
échantillons.
mesurage des concentrations en COT applicables à tous types
d'eau. Elle inclut des définitions, porte sur les interférences, les
réactifs et le prétraitement des échantillons d'eau contenant de
3 Définitions
0,l à 1 O00 mg/l de carbone organique. Des concentrations
plus élevées peuvent être déterminées après dilution appro-
Dans le cadre de la présente Norme internationale, les défini-
priée. Dans certaines circonstances, il peut s'avérer nécessaire
tions suivantes sont applicables.
de prétraiter l'échantillon, par exemple, par séparation des plus
grosses particules contenues dans l'eau, en vue d'éviter le col-
3.1 carbone total (CT) : Quantité de carbone contenue dans
matage de l'appareil.
l'eau sous forme de carbone organique, inorganique ou élé-
mentaire.
La présente Norme internationale ne concerne pas l'aspect ins-
trumental du dosage.
3.2 carbone inorganique total (CIT) : Quantité de carbone
Outre le carbone organique, l'échantillon peut contenir du
contenue dans l'eau sous forme de carbone élémentaire, de
dioxyde de carbone ou des ions d'acide carbonique. Avant la
dioxyde de carbone total, de monoxyde de carbone, de carbu-
détermination du COT, ce carbone inorganique doit être éli-
res, de cyanates, de cyanures et de thiocyanates.
miné, en purgeant l'échantillon acidifié avec du gaz exempt de
CO2 ou de composés organiques. Une autre méthode consiste
3.3 carbone organique total (COT) : Quantité de carbone
à déterminer à la fois le carbone total (CT) et le dioxyde de car-
contenue dans l'eau, dans les matières organiques dissoutes ou
bone total, puis à calculer la teneur en carbone organique
en suspension dans l'eau.
(COT) en soustrayant le dioxyde de carbone total du CT, Cette
méthode ne convient que pour les échantillons dont le dioxyde
3.4 carbone organique dissous (COD): Quantité de car-
de carbone total est inférieur au COT.
bone contenue dans l'eau, dans les matières organiques pas-
sant, durant filtration, à travers une membrane filtrante de
II se peut que des substances organiques volatiles telles
pores de 0,45 pm.
que le benzène, le toluène, le cyclohexane, le chloroforme
1

---------------------- Page: 3 ----------------------
IS0 8245 : 1987 (FI
4 Principe Cette solution reste stable 2 mois environ, si elle est conservée
dans un flacon hermétiquement fermé, dans un réfrigérateur.
Oxydation par combustion, adjonction d'oxydants appropriés
ou irradiation aux ultraviolets du carbone organique de l'eau en
5.2 Hydroghophtalate de potassium, solution étalon,
dioxyde de carbone.
e(C organique) = 100 mg/l.
L'application de la méthode aux ultraviolets où l'oxygène est
Introduire à la pipette 100 ml de la solution mère d'hydrogéno-
l'unique oxydant, est limitée à des eaux non polluées, exemptes
de matières particulaires. Le carbone inorganique est éliminé phtalate de potassium (5.1) dans une fiole jaugée de 1 O00 ml,
compléter avec de l'eau jusqu'au trait repère et mélanger.
par acidification et purge ou déterminé séparément.
Le dioxyde de carbone se formant par oxydation peut être
Cette solution reste stable une semaine environ, si elle est con-
déterminé soit directement, soit après réduction en méthane
servée dans un flacon hermétiquement fermé, dans un réfrigé-
(CH,).
rateur.
Les principes suivants s'appliquent, entre autres, au dosage
5.3 Solution étalon, pour la détermination du carbone
final du CO2 : spectrométrie infrarouge, titrage (de préférence,
inorganique, Q(C inorganique) = 1 O00 mg/l.
en solution non aqueuse), conductivité thermique (TCD), con-
ductimétrie, coulométrie, électrodes spécifiques du CO, et,
Dissoudre dans une fiole jaugée de 1 O00 ml 4,41 g de carbo-
après réduction du CO2 en CH4 ionisation à la flamme (FIDI.
nate de sodium (Na2C03) (séché à 285 OC pendant 1 h) dans
environ 500 ml d'eau. Ajouter 3,50 g d'hydrogénocarbonate de
sodium (NaHC03) (séché sur gel de silice) puis compléter avec
5 Réactifs
de l'eau jusqu'au trait repère.
Utiliser uniquement des réactifs de qualité analytique reconnue
et uniquement de l'eau distillée ou de pureté équivalente. La
Cette solution mère reste stable à la température ambiante.
présente Norme internationale ne mentionne que les produits
chimiques utilisés dans la plupart des méthodes de mesure du
5.4 Autres réactifs
COT. D'autres produits chimiques peuvent être utilisés et, si
nécessaire, prétraités conformément aux instructions du fabri-
5.4.1 Les réactifs 5.1 et 5.2 peuvent être remplacés par
cant.
d'autres solutions de composés stables, dès lors qu'elles satis-
Le COT de l'eau servant aux dilutions et à la préparation des
font aux exigences des substances de titrage.
étalons doit être négligeable par rapport au COT de I'échantil-
Ion.
5.4.2 Acide non volatil, pour l'élimination du dioxyde de
carbone, par exemple, de l'acide phosphorique,
La méthode de prétraitement de l'eau dépend de l'intervalle
c(H3P04) = 0,5 mol/l.
de concentration à mesurer. Les méthodes de prétraitement à
utiliser en fonction du COT de I'bchantillon sont indiquées au
tableau 1.
5.5 Gaz
NOTE - On ne peut stocker de l'eau d'une teneur en COT
Air, azote, oxygène, exempts de dioxyde de carbone et d'impu-
< 0,5 mg/l.
retés organiques.
5.1 Hydrogénophtalate de potassium, solution mère,
e(C organique) = 1 O00 mg/l.
6 Appareillage
Dissoudre dans une fiole jaugée de 1 O00 ml 2,125 g d'hydro-
Matériel courant de laboratoire et
génophtalate de potassium (C8H5KO4) (séché à une tempéra-
ture ne dépassant pas 120 OC pendant 2 hi, dans environ
700 ml d'eau et compléter avec de l'eau jusqu'au trait repère. 6.1 Appareillage de dosage du COT.
Tableau 1 - Méthodes de préparation de l'eau
COT maximum admissible
COT de l'échantillon Exemple de méthode
de l'eau de dilution
hg/l de carbone) de traitement de l'eau
hg/l de carbone)
< 10 o. 1 - traitement par UV
- méthode à la vapeur
- condensation
10à 100 03 - double distill
...