SIST EN ISO 7393-1:2000

SLOVENSKI STANDARD
SIST EN ISO 7393-1:2000
01-december-2000
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SIST ISO 7393-1:1996
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Water quality - Determination of free chlorine and total chlorine - Part 1: Titrimetric
method using N, N-diethyl-1,4-phenylenediamine (ISO 7393-1:1985)
Wasserbeschaffenheit - Bestimmung von freiem Chlor und Gesamtchlor - Teil 1:
Titrimetrisches Verfahren mit N,N-Diethyl-1,4-Phenylendiam (ISO 7393-1:1985)
Qualité de l'eau - Dosage du chlore libre et du chlore total - Partie 1: Méthode
titrimétrique a la N,N-diéthylphénylene-1,4-diamine (ISO 7393-1:1985)
Ta slovenski standard je istoveten z: EN ISO 7393-1:2000
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST EN ISO 7393-1:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 7393-1:2000

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SIST EN ISO 7393-1:2000

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SIST EN ISO 7393-1:2000

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SIST EN ISO 7393-1:2000
International Standard
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.MEXAYHAPO~HAR OPTAHt43AL&lR l-l0 CTAH~APTM3AlJWl~ORGANISATION INTERNATIONALE DE NORMALISATION
Water quality - Determination of free chlorine and
total chlorine -
Part 1: Titrimetric method using
N,/V=diethyl=1,4=phenylenediamine
Qua&! de l’eau - Dosage du chlore libre et du chlore total - Partie I : lM6 thode titrime trique
6 Ia N, N-dikth ylphen ylkne- I,4 diamine
First edition - 1985-09-15
~ ~~
UDC 543.3 : 543.24: 546.13 Ref. No. ISO 7393/1-1985 (EI
Descriptors : watet-, quality, Chemical analysis, determination of content, chlorine, volumetric analysis.
Price based on 8 pages

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SIST EN ISO 7393-1:2000
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of
national Standards bodies (ISO member bedies). The work of preparing International
Standards is normally carried out through ISO technical committees. Esch 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 ISO Council. They are approved in accordance with ISO procedures requiring at
least 75 % approval by the member bodies voting.
International Standard ISO 7393/1 was prepared by Technical Committee
ISO/TC 147, Water quality.
0 International Organkation for Standardization, 1985
Printed in Switzerland

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SIST EN ISO 7393-1:2000
INTERNATIONAL STANDARD ISO 7393/1-1985 (E)
Determination of free chlorine and
Water quality -
total chlorine -
Part 1: Titrimetric method using
N,N-diethyl-1,4=phenylenediamine
0 Introduction 2 Definitions (sec table 1)
ISO 7393 consists of the following park: For the purpose of this part of ISO 7393, the following defini-
tions apply.
Part 1 : Titrimetric method using
N, N-diethyl-1,4-phenylenediamine. 2.1 free chlorine: Chlorine present in the form of
hypochlorous acid, hypochlorite ion or dissolved elemental
Part 2: Colorimetric method using
chlorine.
N, N-diethyl-1,4-phenylenediamine, for routine control
purposes. 2.2 combined chlorine: The fraction of total chlorine
present in the form of chloramines and organic chloramines.
Part 3: lodometric titration method for the determination of
total chlorine. l)
2.3 total chlorine: Chlorine present in the form of “free
chlorine” or “combined chlorine” or both.
1 Scope and field of application 2.4 chloramines: Derivatives of ammonia by Substitution of
one, two or three hydrogen atoms with chlorine atoms
This part of ISO 7393 specifies a titrimetric method for the
(monochloramine NH2CI, dichloramine NHCI,, nitrogen
determination of free chlorine and total chlorine in water.
trichloride NCI,) and all chlorinated derivatives of organic
nitrogen compounds as determined by the method specified in
Sea water and waters containing bromides and iodides com-
this part of ISO 7393.
Prise a group for which special procedures are required.121
The method is applicable to concentrations, in terms of
3 Principle
chlorine Q), from 0,000 4 to 0,07 mmol/l (0,03 to 5 mg/l)
total chlorine and at higher concentrations by dilution of
3.1 Determination of free chlorine
samples. For concentrations above 0,07 mmol/l, ISO 7393/3
tan also be used. Direct reaction with the N, N-diethyl-1,4-phenylenediamine
(DPD) and formation of a red compound at pH 6,2 to 6,5. Titra-
In annex A a procedure is presented for the differentiation of
tion by means of a Standard Solution of ammonium iron(ll)
combined chlorine of the monochloramine type, combined
sulfate to the disappearance of the red colour.
chlorine of the dichloramine type and combined chlorine in the
form of nitrogen trichloride. 3.2 Determination of total chlorine
Several compounds influence the determination specified in Reaction with DPD in the presence of an excess of potassium
this part of ISO 7393. Intetferences are noted in clauses 7 and 9. iodide then titration as in 3.1.
- Terms and synonyms in relation to actual compounds in the Solution
Table 1
Synonym Compounds
Term
Active f ree Elemental chlorine,
chlorine hypochlorous acid
Free chlorine Free chlorine
Potential f ree Hypochlorite
chlorine
Elemental chlorine,
hypochlorous acid,
Total chlorine Total residual chlorine
hypochlorite, chloramines
1) At present at the Stage of draft.

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SIST EN ISO 7393-1:2000
ISO 7393/1-1985 EI
Store the reagent in a dark bottle protected from heat.
4 Reagents
Renew the Solution after 1 month or when it becomes
During the analysis, use only reagents of recognized analytical
discoloured.
grade, and only water as specified in 4.1.
4.4 Potassium iodide, crystals.
Water, free from oxidizing and reducing substances.
4.1
NOTE - Reagents 4.2, 4.3 and 4.4 may be conveniently replaced by
Demineralized or distilled water of which the quality is checked
combined reagents commercially available in the form of stable powder
as follows.
or ta blets.
Into two 250 ml chlorine-demand-free conical flasks (clause 5)
4.5 Ammonium iron(ll) sulfate, stock Solution,
place, in Order,
c[(NHq)2Fe(S04)2~6H201 = 0,056 mol/l.
a) in the first: 100 ml of the water to be checked and
4.5.1 Preparation of the Solution
about 1 g of potassium iodide (4.4); mix and after 1 min add
5 ml buffer Solution (4.2) and 5,0 ml of DPD reagent (4.3);
Dissolve 22 g of ammonium iron(ll) sulfate hexahydrate
(Mohr’s salt) in about 250 ml water (4.1) containing 5 ml
b) in the second: 100 ml of the water to be checked and
sulfuric acid (Q = 184 g/ml) in a 1 000 ml one-mark
two drops of sodium hypochlorite Solution (4.8); then, after
volumetric flask. Make up to the mark with water and mix.
2 min, 5,0 ml of buffer Solution (4.2) and 5 ml of DPD
reagent (4.3).
Store in a dark bottle.
No coloration should appear in the first flask whereas it is
Standardize this Solution by means of the procedure given in
essential that a light pink coloration appears in the second
4.5.2, when required for use, or daily if large numbers of deter-
flask.
minations have to be done.
In the case of demineralized or distilled water not having the
4.5.2 Standardization of the Solution
desired quality it must be chlorinated. After a period of contact
followed by dechlorination the quality finally has to be
Place in a 250 ml conical flask, 50,O ml of the stock Solution
rechecked.
(4.5.11, about 50 ml water (4.11, 5 ml orthophosphoric acid
=
1,71 g/ml) and 4 drops of barium diphenylamine
(@
A procedure for the preparation of water free from oxidizing
sulfonate indicator (4.9). Titrate with potassium dichromate
and reducing substances is given in annex B.
Solution (4.10). The end-point is reached when one drop pro-
duces an intense purple coloration which remains unchanged
4.2 Buffer Solution, pH 6,5.
after further addition of the potassium dichromate Solution.
The concentration, cl, expressed in millimoles of Cl2 per litre, of
Dissolve in water (4.1) in this Order: 24 g anhydrous disodium
this Solution is given by the equation
hydrogen Phosphate (Na2HP04) or 60,5 g of the
dodecahydrate form (Na2HP04m12H20) and 46 g of potassium
dihydrogen Phosphate (KH2PO& Add 100 ml of 8 g/l disodium
dihydrogenethylenedinitrilotetraacetate dihydrate (disodium
EDTA dihydrate, C10H14N208Na2e2H20) Solution (or 0,8 g of
where
the solid ferm).
c2 is the concentration of the potassium dichromate
If necessary, add 0,020 g of mercury(II) chloride (HgCI,), to
Standard reference Solution (4. IO),
prevent mould growth and inter-ference in the free available
cW6 K2Cr207) = 100 mmol/l;
chlorine test caused by any trace amounts of iodide in the
reagents.
VI is the volume, in millilitres, of ammonium iron(ll)
sulfate stock Solution (4.51, 50,O ml;
Dilute to 1 000 ml and mix.
V2 is the volume, in millilitres, of the potassium
NOTE - Solutions containing mercury should be disposed of properly
(for example a method is specified in ISO 5790, lnorganic chemicalpro- dichromate Standard reference Solution (4.10) used in the
General method for determination of
ducts for industrial use - titration.
chloride content - Mercurime tric me thodl .
NOTE - When V2 becomes less than 22 ml, prepare a fresh stock
Solution (sec 4.5.1).
4.3 N,N-diethyl-1,4-phenylenediamine sulfate (DPD)
[NH2-CGH,N(C2H5)2~H2S041, Solution, 1,l g/l.
4.6 Ammonium iron(ll) sulfate, Standard volumetric sol-
ution, c[(NH4)2Fe(S04)2~6H201 = 2,8 mmol/l.
Mix 250 ml water (4.11, 2 ml sulfuric acid (Q = 184 g/ml) and
25 ml of 8 g/l disodium EDTA dihydrate Solution (or 0,2 g of
Place 50,O ml of the freshly standardized stock Solution (4.5.1)
the solid ferm). Dissolve in this mixture 1,l g of anhydrous
DPD or 1,5 g of the pentahydrate form, dilute to 1 000 ml and in a 1 000 ml one-mark volumetric flask. Make up to the mark
with water (4.1) and mix.
mix.
2

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SIST EN ISO 7393-1:2000
ISO 7393/1-1985 (El
Transfer to a dark bottle.
6.2 Test portions
Take two test portions, each of 100,O ml. If the concentration
Prepare this Solution when required for use, or daily if large
of total chlorine exceeds 70 pmol/l (5 mg/l) it is necessary to
numbers of determinations have to be done.
take a smaller volume of test Sample and to dilute with water
(4.1) to 100,O ml.
The concentration, ~3, expressed in millimoles of Cl, per litre, of
this Solution is given by the equation
6.3 Determination of free chlorine
Cl
Place rapidly in a 250 ml conical flask in this Order: 5,0 ml of
c3 = -
20 buffer Solution (4.2), 5,0 ml of DPD reagent (4.3) and the first
test Portion (6.2). Mix and titrate immediately to a colourless
end-point with ammonium iron(ll) sulfate Solution (4.6). Note
where c1 is as defined in 4.5.2.
the volume, VS, in millilitres, used in the titration.
4.7 Sodium arsenite (NaAsO$, Solution, 2 g/l; or
In the case of an unknown water, possibly being very acid, or
thioacetamide (CH&SNH$, Solution, 2,5 g/l.
very alkaline or with a high concentration of salts, it is advisable
to verify that the volume of buffer Solution (4.2) added is suffi-
cient to bring the water to pH 6,2 to 6,5. If not, use a greater
Sodium hypochlorite, Solution [e(Cl,) about 0,l g/l].
4.8
volume of the buffer Solution (4.2).
Prepare by dilution of concentrated commercial sodium
6.4 Determination of total chlorine
hypochlorite Solution.
Place rapidly in a 250 ml conical flask in this Order: 5,0 ml of
buffer Solution (4.21, 5,0 ml of DPD reagent (4.3), the second
4.9 Barium diphenylamine sulfonate, indicator Solution,
test Portion (6.2) and about 1 g of potassium iodide (4.4). Mix
3 gll.
and after 2 min, titrate to a colourless end-point with the am-
monium iron(ll) sulfate Solution (4.6). If within 2 min a drift
Dissolve 0,3 g barium diphenylamine sulfonate
back of colour is observed continue titration to a colourless
[(CGH~NH-C~H4-S03)2Bal in 100 ml water.
end-point. Note the volume, Vd, in millilitres, used in the titra-
tion.
4.10 Potassium dichromate, Standard reference Solution,
In the case of an unknown water, possibly being very acid, or
c(1/6 K$r207) = 100 mmol/l.
very alkaline or with a high concentration of salts, it is advisable
to verify that the volume of buffer Solution (4.2) added is suffi-
Weigh, to the nearest milligram, 4,904 g of anhydrous
cient to bring the water to pH 6,2 to 6,5. If not, use a greater
potassium dichromate. Dissolve in water in a 1 000 ml one-
volume
...