EN 901:2007

SLOVENSKI STANDARD
01-julij-2007
1DGRPHãþD
SIST EN 901:2000
Kemikalije, ki se uporabljajo za pripravo pitne vode - Natrijev hipoklorit
Chemicals used for treatment of water intended for human consumption - Sodium
hypochlorite
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch -
Natriumhypochlorit
Produits chimiques utilisés pour le traitement de l'eau destinée a la consommation
humaine - Hypochlorite de sodium
Ta slovenski standard je istoveten z: EN 901:2007
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 .HPLNDOLMH]DþLãþHQMHYRGH Chemicals for purification of
water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 901
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2007
ICS 71.100.80 Supersedes EN 901:1999
English Version
Chemicals used for treatment of water intended for human
consumption - Sodium hypochlorite
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Hypochlorite de menschlichen Gebrauch - Natriumhypochlorit
sodium
This European Standard was approved by CEN on 10 February 2007.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 901:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.4
Introduction .5
1 Scope .6
2 Normative references .6
3 Description .6
3.1 Identification.6
3.1.1 Chemical name.6
3.1.2 Synonym or common names.6
3.1.3 Relative molecular mass.6
3.1.4 Empirical formula.6
3.1.5 Chemical formula.6
3.1.6 CAS Registry Number .7
3.1.7 EINECS reference .7
3.2 Commercial form .7
3.3 Physical properties.7
3.3.1 Appearance and odour.7
3.3.2 Density .7
3.3.3 Solubility in water .7
3.3.4 Vapour pressure .7
3.3.5 Boiling point at 100 kPa .7
3.3.6 Crystallization and freezing point .7
3.3.7 Specific heat.7
3.3.8 Viscosity (dynamic) .7
3.3.9 Critical temperature.8
3.3.10 Critical pressure.8
3.3.11 Physical hardness .8
3.4 Chemical properties .8
4 Purity criteria.8
4.1 General.8
4.2 Composition of commercial product.8
4.3 Impurities and main by-products.8
4.4 Chemical parameters .9
5 Test methods.9
5.1 Sampling.9
5.2 Analysis .9
5.2.1 Determination of available chlorine content (main product) .9
5.2.2 Impurities.12
5.2.3 Chemical parameters .18
6 Labelling - Transportation - Storage .20
6.1 Means of delivery .20
6.2 Risk and safety labelling according to the EU Directives .21
6.3 Transportation regulations and labelling.22
6.4 Marking.22
6.5 Storage .22
6.5.1 General .22
6.5.2 Long term stability .22
6.5.3 Storage incompatibilities.22
Annex A (informative) General information on sodium hypochlorite.23
A.1 Origin .23
A.2 Use .23
Annex B (normative)  General rules relating to safety .25
B.1 Rules for safe handling and use .25
B.2 Emergency procedures.25
Annex C (normative) Determination of arsenic, antimony and selenium (atomic absorption
spectrometry hydride technique) .26
C.1 General principle .26
C.2 Interferences .26
C.3 Reagents.26
C.4 Apparatus.28
C.5 Procedure.30
C.6 Calculation .31
Annex D (normative) Determination of bromate ion content in sodium hypochlorite by liquid
chromatography of ions and UV detection.32
D.1 General .32
D.2 Interferences .32
D.3 Principle.32
D.4 Reagents.32
D.5 Apparatus.34
D.6 Procedure.34
Annex E (informative) Results of inter-laboratory tests on sodium bromate determination in
sodium hypochlorite commercial solutions.37
Annex F (informative) Environmental, health and safety precautions within chemical laboratories.38
Bibliography.39

Foreword
This document (EN 901:2007) has been prepared by Technical Committee CEN/TC 164 “Water supply”, the
secretariat of which is held by AFNOR.
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 September 2007, and conflicting national standards shall be
withdrawn at the latest by September 2007.
This document supersedes EN 901:1999.
Significant technical differences between this edition and EN 901:1999 are as follows:
a) deletion of the reference to EU Directive 80/778/EEC of 15 July 1980 in order to take account of the latest
Directive in force (see [1]);
b) addition of the limit of the impurity sodium bromate as defined in the EU Directive 98/83/EC and the
method of determination.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.

Introduction
In respect of potential adverse effects on the quality of water intended for human consumption caused by the
product covered by this European Standard:
a) this European Standard provides no information regarding whether the product may be used without
restriction in any of the Member States of the EU or EFTA;
b) it should be noted that, while awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and/or the characteristics of this product remain in force.
NOTE Conformity with this European standard does not confer or imply acceptance or approval of the product in any
of the Member States of the EU or EFTA. Use of the product covered by this European Standard is subject to regulation or
control by National Authorities.
1 Scope
This European Standard is applicable to sodium hypochlorite used for treatment of water intended for human
consumption. It describes the characteristics of sodium hypochlorite and specifies the requirements and the
corresponding test methods for sodium hypochlorite. It gives information on its use in water treatment. It also
determines the rules relating to safe handling and use of sodium hypochlorite (see Annex B).
NOTE While this standard is not applicable to sodium hypochlorite generated in-situ (see bibliographic reference [6])
the limits for impurities and chemical parameters apply.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 1233, Water quality - Determination of chromium - Atomic absorption spectrometric methods
EN 1483, Water quality - Determination of mercury
EN ISO 3696:1995, Water for analytical laboratory use - Specifications and test methods (ISO 3696:1987)
ISO 3165, Sampling of chemical products for industrial use - Safety in sampling
ISO 6206, Chemical products for industrial use - Sampling – Vocabulary
ISO 8288:1986, Water quality - Determination of cobalt, nickel, copper, zinc, cadmium and lead - Flame
atomic absorption spectrometric methods
3 Description
3.1 Identification
3.1.1 Chemical name
Sodium hypochlorite.
3.1.2 Synonym or common names
Liquid bleach, soda bleach, bleach lye.
3.1.3 Relative molecular mass
74,44.
3.1.4 Empirical formula
NaClO.
3.1.5 Chemical formula
NaClO.
1)
3.1.6 CAS Registry Number
7681-52-9.
2)
3.1.7 EINECS reference
231-668-3.
3.2 Commercial form
The product is supplied as an aqueous solution with an available (active) chlorine concentration up to a mass
fraction of 18 %.
3.3 Physical properties
3.3.1 Appearance and odour
The product is a clear yellowish-green solution with a faint chlorinous odour.
3.3.2 Density
The density of the product varies between 1,13 g/ml and 1,30 g/ml at 20 °C.
3.3.3 Solubility in water
The product is capable of being mixed with water in any proportion.
3.3.4 Vapour pressure
Approximately 2,5 kPa at 20 °C.
3)
3.3.5 Boiling point at 100 kPa
Not applicable.
3.3.6 Crystallization and freezing point
At about – 10 °C crystallization of NaOCl . 6 H O starts
Freezing of the concentrated product takes place between - 20 °C and - 30 °C.
3.3.7 Specific heat
The specific heat is 3,48 kJ/(kg.K) for a solution with an available active chlorine concentration of mass
fraction between 14 % and 15 % .
3.3.8 Viscosity (dynamic)
2,6 mPa.s at 20 °C.
1)
Chemical Abstracts Service Registry Number.
2)
European Inventory of Existing Commercial Chemical Substances.
3)
100 kPa = 1 bar.
3.3.9 Critical temperature
Not applicable.
3.3.10 Critical pressure
Not applicable.
3.3.11 Physical hardness
Not applicable.
3.4 Chemical properties
The product is an alkaline solution with a pH value greater than 11 at 20 °C.
It reacts with acids and acidic salts to form chlorine.
-
Vigorous reactions occur with reducing chemicals. It is a strong oxidant (E° for (ClO ) = 0,89 V).
Red
- + - -
ClO + 2H +2e → Cl + H O
4 Purity criteria
4.1 General
This European Standard specifies the minimum purity requirements for sodium hypochlorite used for treating
water intended for human consumption. Limits are given for impurities commonly present in the product.
Depending on the raw material and the manufacturing process other impurities may be present and, if so, the
user, and when necessary the relevant authorities, shall be notified.
NOTE Users of the product should check the national regulations to clarify whether it is of appropriate purity for
treating water intended for human consumption, taking into account raw water quality, required dosage, contents of other
impurities and additives used in the product that are not stated in this product standard
Limits have been given for impurities and chemical parameters where these are likely to be present in
significant quantities from the current production process and raw materials. If in the production process or
raw materials lead to the presence of significant amounts of impurities, by-products or additives, the user shall
be notified.
4.2 Composition of commercial product
Sodium hypochlorite is available only in solutions with concentrations up to 18 % active chlorine at the time of
delivery by the producer. Common concentrated products contain a minimum of 12 % active chlorine. Diluted
solutions are also available.
The concentration of sodium hypochlorite shall be equal to or greater than the value specified by the
manufacturer.
4.3 Impurities and main by-products
The product contains sodium chloride (NaCl) in equimolar amounts at minimum, and a small portion of sodium
hydroxide (NaOH) which keeps the product alkaline. Thus a little amount of sodium carbonate (Na CO ) can
2 3
be present, too.
The sodium chlorate (NaClO ) content shall not exceed a mass fraction of 5,4 % of available chlorine at the
time of delivery by the producer. The product shall be visibly free from deposits or suspended matter.
NOTE Sodium chlorate is a by-product of the manufacturing process and can be formed during storage (see 6.5.1).
4.4 Chemical parameters
The product shall conform to the requirements specified in Table 1.
Table 1 – Chemical parameters
Parameter Limit in mg/kg
of available chlorine
Type 1 Type 2
Arsenic (As) max. 1 5
Antimony (Sb) max.      20 25
Cadmium (Cd) max.      2,5 5
Chromium (Cr) max.      2,5 5
Lead (Pb) max.      15 15
Mercury (Hg) max.      3,5 5
Nickel (Ni) max.      2,5 10
Selenium (Se) max.      20 25
Limit in g/kg
of available chlorine
a
Sodium bromate max2,5 5,0
NOTE Cyanide, which does not exist in a strong oxidizing medium such as sodium
hypochlorite, is not a relevant chemical parameter. Pesticides and polycyclic aromatic
hydrocarbons are not by-products of the manufacturing process. For parametric values
of sodium hypochlorite on trace metal content in drinking water, see bibliographic
reference [1].
a
Sodium bromate is a by-product of the manufacturing process.

5 Test methods
5.1 Sampling
Observe the general recommendations of ISO 3165 and take account of ISO 6206.
5.2 Analysis
5.2.1 Determination of available chlorine content (main product)
5.2.1.1 General
This method applies to all commercial products with available chlorine contents within the range of 70 g/l to
170 g/l.
NOTE It detects all oxidizing agents being active in weak acidic solutions, i.e. hypochlorite/chlorine, iodate, and
partially chloramines, Fe(III), etc. Not covered under these conditions are bromate and chlorate.
5.2.1.2 Principle
Sodium hypochlorite reacts with potassium iodide to release iodine in the presence of acetic acid. The iodine
is titrated with sodium thiosulfate standard volumetric solution in the presence of starch indicator solution.
NOTE The titration can also be carried out potentiometrically by the aid of titration automates; when this occurs, the
addition of soluble starch is unnecessary.
5.2.1.3 Reagents
All reagents shall be of a recognized analytical grade and the water used shall conform to grade 3, as
specified in EN ISO 3696:1995 (de-ionized water for common laboratory purposes).
5.2.1.3.1 Potassium iodide solution, mass fraction 10 % .
Weigh, to the nearest 0,1 mg, 100 g of potassium iodide, iodate-free, and dissolve in water and dilute to 1 l.
5.2.1.3.2 Acetic acid concentrated, of purity at least of mass fraction 99 % .
5.2.1.3.3 Sodium thiosulfate standard volumetric solution, c(Na S O .5H O) = 0,1 mol/l.
2 2 3 2
Standard volumetric solutions are commercially available and eventually they have to be diluted.
Alternatively, a standard volumetric solution can be prepared by the following procedure:
Dissolve 24,8 g Na S O . 5 H O in a 1 000 ml one-mark volumetric flask in 0,75 l of water. After the
2 2 3 2
temperature has equalized, make up to the mark with water and mix thoroughly.
To standardize: Weigh, to the nearest 0,1 mg, 3,600 g (m) of dry potassium iodate. Dissolve in water in a
1 000 ml one-mark volumetric flask, make up to the mark with water and mix (standard reference solution
c(1/6 KIO ) = 0,1 mol/l ). Place 200 ml of water in a 500 ml stoppered conical flask, add (2 ± 0,5) g of
potassium iodide and stir to dissolve. Then introduce, by means of a pipette, 10,0 ml of sodium thiosulfate
solution for standardization, add (15 ± 1) ml of hydrochloric acid solution (diluted 1 + 1 by volume) and
(5 ± 1) ml of starch solution (5.2.1.3.4). Titrate immediately with the potassium iodate standard reference
solution until the appearance of a blue coloration that persists for 30 s. Record the volume (V ) of iodate used.
The actual concentration, c, of the sodium thiosulfate standard volumetric solution (Na S O .5H O), expressed
2 2 3 2
in moles/l is given by Equation (1):
V ×c
1 1
c = (1)
V
where
c is the concentration, expressed in moles/l, of the potassium iodate standard reference solution [c(1/6
KIO ) = 0,1 mol/l ];
V is the volume, in ml, of the sodium thiosulfate standard volumetric solution used for the

standardization (V= 10 ml);
V is the volume, in ml, of potassium iodate standard reference solution used in the titration.
5.2.1.3.4 Starch solution, mass fraction of 1 %:
Make a slurry with (1 ± 0,1) g of starch and (5 + 1) ml of water. Add (90 ± 5) ml of boiling water to the slurry.
Stir to dissolve it and cool the solution. This solution needs to be refrigerated to avoid the decomposition of the
starch which results in a vague end point. Keep the solution cool and use it within 1 week.
NOTE Commercial indicators for iodine titration exist and can be used in place of the described starch solution,
provided that their efficiency has been previously tested.
5.2.1.4 Apparatus
Ordinary laboratory apparatus and glassware.
5.2.1.5 Procedure
5.2.1.5.1 Test solution
Weigh to the nearest 0,1 mg 1 g of the laboratory sample (record mass m in grams) into a 250 ml conical
flask and dilute with water up to 100 ml.
5.2.1.5.2 Determination
Add 10 ml of the potassium iodide solution (5.2.1.3.1) and 5 ml of concentrated acetic acid (5.2.1.3.2).
Titrate at once with the sodium thiosulfate standard volumetric solution (5.2.1.3.3) until the iodine colour is
nearly gone. Add 3 ml of the starch indicator solution (5.2.1.3.4) and complete the titration until the
disappearance of the blue-black colour. Record the volume V , of the sodium thiosulfate standard volumetric
solution added.
5.2.1.6 Expression of results
The available chlorine (Cl ) content, C , expressed in mass fraction % (w/w), is given by Equation (2):
2 2
C = (V x c x 3,545) / (m ) (2)
1 1 1
where
V is the volume, in millilitres, of the sodium thiosulfate standard volumetric solution (5.2.1.3.3);
c is the concentration in moles per litre, of the sodium thiosulfate standard volumetric solution (see
5.2.1.3.3);
3,545 is the mass in milligrams of chlorine (Cl ) corresponding to 1 ml of sodium thiosulfate solution of
c(Na S O .5H O) = 0,100 mol/l;
2 2 3 2
m is the mass in g of the laboratory sample used to prepare the test solution (5.2.1.5.1).
5.2.2 Impurities
5.2.2.1 Determination of sodium chlorate content (NaClO )
5.2.2.1.1 General
This method is used to determine the chlorate content, in the range between 3,75 g/l and 15 g/l, in sodium
hypochlorite solutions for commercial use ; it is specific for these species.
5.2.2.1.2 Principle
Direct determination of chlorate ions in a diluted solution of sodium hypochlorite by ion chromatography with
suppressed conductimetric detection.
5.2.2.1.3 Reagents
All reagents shall be of a recognized analytical grade and the water used shall have a conductivity of
0,056 µS/cm (conform to grade 1, as specified in EN ISO 3696:1995).
5.2.2.1.3.1 Sodium carbonate and sodium hydrogen carbonate, eluant solution.
Mix one volume of sodium carbonate solution c(Na CO ) = 2 mmol/l with one volume of sodium hydrogen
2 3
carbonate solution c(NaHCO ) = 0,75 mmol/l.
5.2.2.1.3.2 Sulfuric acid solution c(H SO ) = 0,025 mol/l regenerant solution.
2 4
5.2.2.1.3.3 Helium gas, high purity, for degassing eluant and regenerant solutions.
5.2.2.1.3.4 Sodium chlorate stock solution at 1 g/l.
Weigh, to the nearest 0,000 1 g, 0,255 1 g of NaClO Dissolve in 200 ml of the water (grade 1, EN ISO
3696:1995).
5.2.2.1.4 Apparatus
Ordinary laboratory apparatus and glassware, together with the following.
5.2.2.1.4.1 Ion chromatograph.
5.2.2.1.4.2 Chemical suppressed conductivity detector.
5.2.2.1.4.3 Anionic column and pre-column:
Resin composed of 15 µm polystyrene/divinylbenzene substrate agglomerated with anion exchange latex that
has been aminated.
5.2.2.1.4.4 Data logger/plotter, able to record and display the chromatographic peak heights.
5.2.2.1.4.5 Generator of water (grade 1, EN ISO 3696:1995).
5.2.2.1.5 Chromatographic conditions
 eluant flow rate: 2 ml/min ;
 regenerant flow rate: 2,5 ml/min ;
 full scale of conductivity: 30 mS ;
 residual conductivity: < 18 mS ;
5.2.2.1.6 Procedure
5.2.2.1.6.1 Preparation of calibration solutions
Prepare calibration solutions in volumetric flasks by diluting accurately measured volumes of the chlorate
stock solution (5.2.2.1.3.4) with the eluant solution (5.2.2.1.3.1), in accordance with Table 2.
Table 2 - Calibration solutions for determination of chlorate content
Solution ClO - inmg/l NaClO in mg/l
1 3,75 4,78
2 7,5 9,57
3 11,25 14,35
4 15 19,13
NOTE Calibration is linear for concentration of chlorate ion between 3,75 mg/l and 15 mg/l in the diluted solution.
5.2.2.1.6.2 Preparation of test solution
Weigh to the nearest 0,1 mg 250 mg of the laboratory sample (record mass m in milligrams) into a 100,0 ml
measuring flask, fill up with eluant solution (5.2.2.1.3.1) and homogenize the test solution by shaking the
sealed flask carefully.
5.2.2.1.6.3 Measurement of calibration and test solutions
Measure each calibration and test solution three times using a constant injection volume according to the
requirements of the respective ion chromatograph. For each solution the relative repeatability standard
deviation shall be lower than 0,5 %.
5.2.2.1.7 Expression of results
The sodium chlorate content of the test solution (y in mg/l) is calculated from the calibration line which is
obtained by linear regression with the five levels (four chlorate solutions and one blank solution) in the
calibration procedure.
The sodium chlorate (NaClO ) content of the laboratory sample, C , expressed in grams per kilograms is
given by Equation (3):
C =(y×V ) /m (3)
2 2 2
where
y is the concentration of the test solution in milligrams per litre obtained via the regression line of the
calibration;
V is the volume, in millilitres, of the test solution (5.2.2.1.6.2);
m is the mass of the laboratory sample, in milligrams (5.2.2.1.6.2).
The sodium chlorate (NaClO ) content of the laboratory sample, C expressed in mass fraction % (w/w) of
available chlorine is given by Equation (4):
(C ×10)
C = (4)
C
where
C is the sodium chlorate (NaClO ) content in g/kg of the laboratory sample;
2 3
C is the available chlorine (Cl ) content in mass fraction % (w/w) (5.2.1.6).
1 2
5.2.2.1.8 Repeatability limit
The absolute difference between two single test results, obtained under repeatability conditions, shall not be
greater than the repeatability value, r, as calculated from Equation (5):
r = 0,001 z (5)
where
z is the mean of the two results, expressed in mass fraction in percentage (%) .
NOTE Repeatability conditions are conditions where mutually independent test results are obtained with the same
method on identical test material in the same laboratory by the same operator using the same equipment within short
intervals of time.
5.2.2.2 Determination of sodium bromate content (NaBrO )
5.2.2.2.1 General
This method is used to determine the bromate content, in the range between 2 mg/l and 1 000 mg/l, in sodium
hypochlorite solutions for commercial use.
5.2.2.2.2 Principle
Direct determination of bromate ions in a diluted solution of sodium hypochlorite by ion chromatography with
suppressed conductimetric detection.
The range of measurement can be limited by analytical column capacity. A dilution of the sample in the
measurement range can be necessary. A convenient pre-treatment of the sample might be required (for
example to remove any chloride, sulfate, carbonate or metals).
NOTE Direct determination of bromate by separation and indirect UV detection can also be carried out. The complete
analytical procedure is described in Annex D.
5.2.2.2.3 Reagents
All reagents shall be of a recognized analytical grade and the water used shall have a conductivity of 0,056
µS/cm (conform to grade 1 as specified in EN ISO 3696:1995).
5.2.2.2.3.1 Sulfuric acid solution c(H SO ) = 0,025 mol/l regenerant solution.
2 4
5.2.2.2.3.2 Helium gas, high purity, for degassing eluant and regenerant solutions.
5.2.2.2.3.3 Stock sodium carbonate solution, c(Na CO ) = 0,5 mol/l.
2 3
Dissolve 53,0 g of anhydrous sodium carbonate in 800 ml of water (grade 1, EN ISO 3696:1995) in a 1 000 ml
volumetric flask and make up to the volume with water (grade 1, EN ISO 3696:1995).
Store the solution at 2°C to 6°C in a polyethylene or glass bottle and renew it every 6 months.
5.2.2.2.3.4 Eluent carbonate solution, c(Na CO ) = 0,009 mol/l
2 3
Introduce 36 ml of the stock sodium carbonate solution 0,5 mol/l (5.2.2.2.3.3) into a 2 000 ml volumetric flask
and make up to the volume with water (grade 1, EN ISO 3696:1995).
Store the solution at 2 °C to 6 °C in polyethylene or glass bottle and renew it every week.
Degas the solution with helium (5.2.2.2.3.2) before use according to the instructions given by the
manufacturer.
NOTE Eluent should be maintained under an inert helium atmosphere to avoid carbonate contamination.
5.2.2.2.3.5 Stock standard bromate solution,w(BrO )=1 000 mg/l
Dry 1,5 g of potassium bromate for at least 1 h at 105 °C. Store the dried product in a desiccator. Weigh, to
the nearest 0,0 001 g ,1,3 057 g of the dry potassium bromate. Introduce into a 1 000 ml volumetric flask.
Dissolve in 800 ml of water (grade 1, EN ISO 3696:1995) and make up to the volume with water (grade 1, EN
ISO 3696:1995). Store the solution at 2 °C to 6 °C in polyethylene or glass bottle and renew it every 12
months.
A commercial standard stock solution at required concentration may be also used.
5.2.2.2.3.6 Bromate standard solution, w(BrO )=10 mg/l
Introduce 1 ml of stock standard bromate solution (5.2.2.2.3.5) into a 100 ml volumetric flask. Make up to the
volume with water (grade 1, EN ISO 3696:1995).
Store the solution at 2 °C to 6 °C in polyethylene or glass bottle and renew it every 3 months.
5.2.2.2.4 Apparatus
Ordinary laboratory apparatus and glassware, together with the following.
5.2.2.2.4.1 Ion chromatograph
5.2.2.2.4.2 Chemical or electrochemical suppressed conductivity detector
5.2.2.2.4.3 Anionic column and pre-column
Resin composed of 15 µm polystyrene/divinylbenzene substrate agglomerated with anion exchange latex that
has been aminated.
5.2.2.2.4.4 Pre-treatment cartridges
- Cationic exchangers as Ag-form (Silver) (cartridge);
- Cationic exchangers as H-form (Hydrogen) (cartridge).
If necessary, cationic exchangers as Ba-form (Barium) (cartridge) may be used to suppress sulfate
interferences.
5.2.2.2.4.5 Generator, of water (grade 1, EN ISO 3696:1995).
5.2.2.2.5 Chromatographic conditions
 eluant flow rate: 1 ml/min;
 regenerant flow rate: 2,5 ml/min or electrochemical regeneration;
 recommended sampling loop size: 50 µl to 100 µl.
5.2.2.2.6 Procedure
5.2.2.2.6.1 Preparation of calibration solutions
Prepare calibration solutions in volumetric flasks by diluting accurately measured volumes of the bromate
stock solution (5.2.2.2.3.5) with the eluant carbonate solution (5.2.2.2.3.4) in accordance with Table 3.
Table 3 - Calibration solutions for determination of bromate content
Solution BrO - inmg/l NaBrO3 in mg/l
1 0,2 0,236
2 0,5 0,59
3 1 1,18
4 2 2,36
NOTE 1 Calibration is linear for concentration of bromate ion between 0,2 mg/l and 2 mg/l in the diluted solution.
NOTE 2 Prepare the calibration solutions freshly on the day of use.
5.2.2.2.6.2 Sample pre-treatment (if required)
If sample pre-treatment is necessary (presence of chloride and/or carbonate in large amount in the sample
that can interfere with the bromate determination), calibration solutions and diluted test solutions shall be
treated as follows:
 connect the cationic exchangers (cartridges) in series in order of Ag-H;
 using a 10 ml syringe, flush the cartridges with 10 ml of water;
 fill a 10 ml syringe with sample and attach it to the cartridge set;
 flush it with 5 ml of sample;
 continue to inject sample through the cartridges and collect the next 5 ml of treated sample for analysis;
 purge the treated sample with helium gas for 5 min to remove the remaining carbonate.
NOTE if necessary, a Ba-form cartridge can be added to remove sulfate; the three pre-treatment cartridges should
then be attached in the following order: Ba-form, Ag-form, and H-form.
5.2.2.2.6.3 Preparation of test solutions
Weigh to the nearest 0,1 mg 250 mg of the laboratory sample (record mass m in milligrams) into a 100,0 ml
2'
measuring flask, fill up with eluant solution (5.2.2.2.3.4) and homogenize the test solution by shaking the
sealed flask carefully.
5.2.2.2.6.4 Measurement of calibration and test solutions.
Measure each calibration solution and test solution three times using a constant injection volume according to
the requirements of the respective ion chromatograph. For each solution the relative repeatability standard
deviation shall be lower than 0,5 %.
5.2.2.2.7 Expression of results
The sodium bromate content of the test (y' in mg/l) is calculated from the calibration line which is obtained by
linear regression with the five levels (4 bromate solutions and 1 blank solution) in the calibration procedure.
The sodium bromate (NaBrO ) content of the laboratory sample, C’ , expressed in milligrams per kilograms is
given by Equation (6):
C' =y' x V ' x 10) / m ' (6)
2 2 2
where
y’ is the concentration of the test solution in mg/l obtained via the regression line of the calibration;
v2' is the volume in millilitres of the test solution (5.2.2.6.3);
m2' is the mass of the laboratory sample in milligrams (5.2.2.6.3).
The sodium bromate (NaBrO ) content of the laboratory sample, C’ , expressed in mass fraction of available
3 3
chlorine is given by Equation (7):
C' = (C '×10 ) / C (7)
3 2 1
where
C ' is the sodium bromate (NaBrO3) content in mg/kg of the laboratory sample;
C is the available chlorine (Cl ) content in mass fraction % (w:w) (5.2.1.6).
1 2
5.2.2.2.8 Repeatibility limit
The absolute difference between two single test results, obtained under repeatability conditions, shall not be
greater than the repeatability value, r, as calculated from Equation (8):
r = 0,005 z           (8)
where
z is the mean of the two results, expressed in mass fraction in percent (%).
NOTE Repeatability conditions are conditions where mutually independent test results are obtained with the same
method on identical test material in the same laboratory by the same operator using the same equipment within short
intervals of time.
5.2.3 Chemical parameters
5.2.3.1 Determination of antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), nickel
(Ni) and selenium (Se)
5.2.3.1.1 Principle
The elements arsenic, antimony, cadmium, chromium, lead, nickel and selenium are determined by atomic
absorption spectrometry.
5.2.3.1.2 Reagents
All reagents shall be of a recognized analytical grade and the water used shall conform to grade 2 as specified
in EN ISO 3696:1995.
5.2.3.1.2.1 Nitric acid, concentrated, density ρ = 1,42 g/ml.
5.2.3.1.3 Procedure
5.2.3.1.3.1 Test portion
Weigh, to the nearest 0,001 g, 20 g (m ) from the laboratory sample into a glass beaker.
5.2.3.1.3.2 Test solution
Evaporate until a wet residue is obtained, cool, add 1 ml of nitric acid (5.2.3.1.2.1), dilute with a few millilitres
of water, transfer quantitatively to a 100 ml volumetric flask, make up to the volume with water and mix.
Carry out the evaporation carefully and not to dryness in order to avoid possible losses of arsenic and
selenium.
5.2.3.1.3.3 Determination
Determine the content of elements in the test solution (5.2.3.1.3.2) in accordance with the following methods:
 Cd, Ni and Pb: In accordance with ISO 8288:1986, Method A;
 Cr: In accordance with EN 1233;
 As, Se and Sb: In accordance with the method given in Annex C.
These methods will give an interim result (y) expressed in milligrams per litre which needs to be converted to
give the final concentration according to the equation in 5.2.3.1.3.4.
5.2.3.1.3.4 Expression of results
From the interim result (y) determined (see 5.2.3.1.3.3), the content, C , of each element in the laboratory
sample, expressed in milligrams per kilogram of available chlorine is given by Equation (9):
V 100
C = y x x (9)
m C
2 1
where
y is the interim result (5.2.3.1.3.3);
V is the volume, expressed in millilitres, of the test solution (5.2.3.1.3.2) (here V = 100 ml);
m is the mass, expressed in grams, of the test portion;
C is the available chlorine (Cl ) content in mass fraction in % (5.2.1.6).
1 2
5.2.3.2 Determination of mercury content (Hg)
5.2.3.2.1 Principle
The element mercury is determined by flameless atomic absorption spectrometry in accordance with EN 1483.
5.2.3.2.2 Reagents
All reagents shall be of a recognized analytical grade and the water used shall conform to the grade 3 as
specified in EN ISO 3696:1995.
5.2.3.2.2.1 Nitric acid, mass fraction 65 %.
5.2.3.2.2.2 Sulfuric acid, mass fraction 30 %.
5.2.3.2.2.3 Hydroxylammonium chloride,solution (NH OH.HCl) ,mass fraction 10 % l.
5.2.3.2.2.4 Tin (II) chloride solution, mass fraction 10 %.
5.2.3.2.3 Procedure
5.2.3.2.3.1 Test portion
Pipette 10 g (m ) of the laboratory sample and transfer to approximately 70 ml of water taking care to avoid
sputtering.
5.2.3.2.3.2 Test solution
Quantitatively transfer the test portion to a gas washing flask, capacity 250 ml, with the gas inlet equipped with
a porous glass frit. Dilute the contents of the gas washing flask with water to obtain a total volume of 100 ml.
Transfer to a volumetric flask (solution A).
Pipette, accurately 5 ml of the sodium hypochlorite (solution A) and dilute in a 250 ml graduated gas washing
flask. During gentle shaking add 30 ml of hydroxylammonium chloride solution (5.2.3.2.2.3), 5 ml of nitric acid
(5.2.3.2.2.1) and 2 ml of tin (II) chloride solution (5.2.3.2.2.4) successively. Close immediately the gas washing
flask with the gas inlet equipped with a porous glass frit.
5.2.3.2.3.3 Deter
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