EN 12678:2008

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kemikalije, ki se uporabljajo za pripravo pitne vode - Kalijev peroksomonosulfatProdukte zur Aufbereitung von Wasser für den menschlichen Gebrauch - KaliumperoxomonosulfatProduits chimiques utilisés pour le traitement de l'eau destinée à la consommation humaine - Peroxomonosulfate de potassiumChemicals used for treatment of water intended for human consumption - Potassium peroxomonosulfate71.100.80Chemicals for purification of water13.060.20Pitna vodaDrinking waterICS:Ta slovenski standard je istoveten z:EN 12678:2008SIST EN 12678:2008en,fr,de01-november-2008SIST EN 12678:2008SLOVENSKI
STANDARDSIST EN 12678:20011DGRPHãþD

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12678July 2008ICS 71.100.80Supersedes EN 12678:2000
English VersionChemicals used for treatment of water intended for humanconsumption - Potassium peroxomonosulfateProduits chimiques utilisés pour le traitement de l'eaudestinée à la consommation humaine - Peroxomonosulfatede potassiumProdukte zur Aufbereitung von Wasser für denmenschlichen Gebrauch - KaliumperoxomonosulfatThis European Standard was approved by CEN on 28 June 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial 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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2008 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12678:2008: ESIST EN 12678:2008

General information on potassium peroxomonosulfate.16 Annex B (normative)
General rules relating to safety.18 Annex C (normative)
Determination of arsenic, antimony and selenium (atomic absorption spectrometry hydride technique).19 Bibliography.25
1) Chemical Abtracts Service Registry Number. 2) European Inventory of Existing Commercial Chemical Substances. 3) 100 kPa = 1 bar SIST EN 12678:2008

'
HSO4- + H2O
(1) is:
+ 1,82 V at 25°C 4 Purity criteria 4.1 General This European Standard specifies the minimum purity requirements for Potassium peroxomonosulfate used for the treatment of 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, this shall be notified to the user and when necessary to the relevant authorities. NOTE Users of this product should check the national regulations in order to clarify whether it is of appropriate purity for treatment of water intended for human consumption, taking into account raw water quality, required dosage, contents of other impurities and additives used in the product not stated in the product standard. Limits have been given for impurities and chemicals parameters where these are likely to be present in significant quantities from the current production process and raw materials. If the production process or raw materials leads to significant quantities of impurities, by-products or additives being present, this shall be notified to the user. 4.2 Composition of commercial product The commercial product shall contain KHSO5 (potassium peroxomonosulfate) at a mass fraction greater than 45 per cent or the manufacturer’s declared values. NOTE Typical composition in mass fraction should be approximately 45 % KHSO5, potassium hydrogen sulfate (KHSO4), 25 % and potassium sulfate (K2SO4) 30 % . SIST EN 12678:2008

Type 1 Type 2 Arsenic (As) max. 2 10 Cadmium (Cd) max. 1 10 Chromium (Cr) max. 0,4 10 Mercury (Hg) max. 4 8 Nickel (Ni) max. 1 10 Lead (Pb) max. 2 10 Antimony (Sb) max. 10 10 Selenium (Se) max. 10 10 NOTE Cyanide is usually not relevant in a strong oxidizing medium. Pesticides and polycyclic aromatic hydrocarbons are not by-products of the manufacturing process. 5 Test methods 5.1 Sampling Observe the general recommendations of ISO 3165 and take account of ISO 6206. Prepare the laboratory sample(s) required by the relevant procedure described in ISO 8213. 5.2 Analysis 5.2.1 Determination of potassium peroxomonosulfate (KHSO5) (active ingredient) 5.2.1.1 Principle Iodometric titration with sodium thiosulfate standard volumetric solution in sulfuric acid medium. The method depends on the oxidizing action of the peroxomonosulfate ion (HSO5)- on iodide ions, Equation (2) and the subsequent determination of iodine formed, through the reducing agent sodium thiosulfate, Equation (3). The inflection point of the potentiometric titration is located around 250 mV (reference to Ag/AgCl-Electrode). HSO5- + 3 Kl + H2SO4 → HSO4- + Kl3 + K2SO4 + H2O (2) Kl3 + 2 Na2S2O3 → Kl + 2 Nal + Na2S4O6 (3) SIST EN 12678:2008

Place 750 ml of water in a heat resistant beaker (volume 2 000 ml). Measure 135 ml of sulfuric acid, mass fraction 98 % , and dilute in the water by small additions and under gentle stirring. Cover the beaker with a watch glass and keep it for several hours in a safe place to cool. SAFETY PRECAUTIONS: During dilution the solution becomes hot; wear safety goggles, protective gloves and protective clothing. 5.2.1.2.2 Hydrochloric acid solution, mass fraction 10 %
5.2.1.2.3 Potassium iodide solution, mass fraction 30 %
Weigh, to the nearest 0,1 g, 60 g of potassium iodide, iodate-free grade, and dissolve it in 140 ml of water. Keep the solution in a dark place. 5.2.1.2.4 Starch solution, mass fraction 1 %
Weigh 1,00 g of soluble starch and make a slurry with 5 ml of water. Add 95 ml of water to the slurry and boil for several minutes to dissolve it. Cool the solution. This solution needs refrigeration to avoid decomposition of the starch which results in a vague end point. Keep the solution cool and use it within one week. NOTE Commercial starch solutions as indicators for iodine titration exist and can be used in place of the specified starch solution provided that their efficiency has been previously tested. 5.2.1.2.5 Potassium iodate (KIO3) 5.2.1.2.6 Sodium thiosulfate standard volumetric solution, c(Na2S2O3.5H2O) = 0,1 mol/l Standard volumetric solutions of sodium thiosulfate are commercially available.
Alternatively a standard volumetric solution can be prepared by the following procedure:
Dissolve 24,8 g Na2S2O3 . 5 H2O in a 1 000 ml one-mark volumetric flask in about 0,75 l water. After the temperature has equalized makeup 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 KIO3) = 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 (5.2.1.2.4). Titrate immediately with the potassium iodate standard reference solution until the appearance of a blue coloration persisting for at least 30 s occurs. Record the volume (V1) of iodate used.
The actual concentration, c, of the sodium thiosulfate standard volumetric solution (Na2S2O3.5H2O), expressed in moles per litre is given by the following equation :
VcV11c×=
(4)
where
c1 is the concentration, expressed in moles per litre, of the potassium iodate standard reference solution [c(1/6 KIO3) = 0,1 mol/l ];
is the volume, in millilitres, of the sodium thiosulfate standard volumetric solution used for the standardization (V= 10 ml);
V1 is the volume, in millilitres, of potassium iodate standard reference solution used in the titration.
5.2.1.3 Apparatus Ordinary laboratory apparatus and glassware together with the following: 5.2.1.3.1 Potentiometric titrimeter. 5.2.1.3.2 Automatic burette, volume 50 ml, equipped with an injection tip (made of brown glass). 5.2.1.3.3 Electromechanical stirrer. 5.2.1.3.4 Glass titration beaker, capacity 250 ml (made of brown glass). 5.2.1.3.5 Platinum-Ag/AgCl combination electrode with electrolytic junction with built-in diaphragm. 5.2.1.4 Procedure 5.2.1.4.1 Test solution Weigh, to the nearest 0,1 mg, a test portion of approximately 0,7 g (m) into a dry, clean beaker (5.2.1.3.4). Add 20 ml of potassium iodide solution (5.2.1.2.3) and 10 ml of sulfuric acid (5.2.1.2.1). After dissolution under gentle stirring cover the beaker with a watch glass and keep the solution in the dark for 30 min. Then add 100 ml of water. 5.2.1.4.2 Determination Input the calculation data in the titration microprocessor in accordance with the instruction manual. Place the electrodes in the titration beaker and titrate with the sodium thiosulfate solution (5.2.1.2.6). Record the titration curve and determine the inflection point as the equivalent point of the potentiometric titration. 5.2.1.5 Expression of results The potassium peroxomonosulfate (KHSO5) content, C1, expressed as a percentage by mass, is given by the following equation: mV76,1
c
1××=C
(5) where
V is the volume, expressed in millilitres, of the sodium thiosulfate standard volumetric solution (5.2.1.2.6) used for the titration; c is the concentration, in moles per litre, of the sodium thiosulfate solution (5.2.1.2.6) ; m is the mass of the test portion, expressed in grams. 76,1 is the mass in grams of KHSO5 corresponding to 1 000 ml of sodium thiosulfate c(Na2S2O3.5H2O) = 0,1mol/l. SIST EN 12678:2008

(6) where
z
is the mean of the two results, expressed in mass fraction %. NOTE Repeatibility conditions are conditions where mutually independant 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 Chemical parameters 5.2.2.1 Determination of antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni) and selenium (Se) 5.2.2.1.1 Principle The elements arsenic, antimony, cadmium, chromium, lead, nickel and selenium are determined by atomic absorption spectrometry. 5.2.2.1.2 Reagents All reagents shall be of a recognised analytical grade and the water used shall conform to the appropriate grade specified in EN ISO 3696. 5.2.2.1.2.1 Nitric acid, concentrated, density ρ = 1,42 g/ml. 5.2.2.1.2.2 Nitric acid, solution, c (HNO3) = 2,5 mol/l. 5.2.2.1.2.3 Barium nitrate, Ba (NO3)2. 5.2.2.1.3 Procedure 5.2.2.1.3.1 Test portion Weigh, to the nearest 0,01 g:
 for Cd, Ni, Pb, As and Sb: 1 g (m) of the laboratory sample into a 100 ml one-mark volumetric flask;  for Cr: 2 g (m) of the laboratory sample into a 100 ml one-mark volumetric flask;  for Se: 0,5 g (m) of the laboratory sample into a 100 ml one-mark volumetric flask. 5.2.2.1.3.2 Test solution For Cd: dissolve the test portion with 40 ml of water and after adding 20 ml of barium nitrate (5.2.2.1.2.3), bring solution briefly to boiling point and after cooling dilute to volume with water and homogenize. The determination is made with the clear supernatant solution after the barium sulfate has settled out.
For Cr and Ni: add 0,5 ml of nitric acid (5.2.2.1.2.2) to the test portion, dilute with a few millilitres of water and mix. Dilute to volume with water and homogenize. For Pb and As: dissolve the test portion with a few millilitres of water and mix. Dilute to volume with water and homogenize. SIST EN 12678:2008

(7) Where y is the interim result (5.2.2.1.3.3); V is the volume, expressed in millilitres, of the test solution (5.2.2.1.3.2) (= 100 ml); m is the mass, expressed in grams, of the test portion; C1 is the potassium peroxomonosulfate content in percentage by mass of product (see 5.2.1.5). 5.2.2.2 Determination of the mercury content (Hg) 5.2.2.2.1 Principle The element mercury is determined by flameless atomic absorption spectrometry in accordance with EN 1483. 5.2.2.2.2 Reagents All reagents shall be of a recognised analytical grade and the water used shall conform to the appropriate grade specified in EN ISO 3696. 5.2.2.2.2.1 Potassium permanganate solution, c(KMnO4) = 50 g/l. 5.2.2.2.2.2 Sulfuric acid, concentrated, density ρ = 1,84 g/ml. 5.2.2.2.2.3 Hydroxylammonium chloride solution, c(NH2OH.HCl) = 100 g/l. 5.2.2.2.2.4 Potassium dichromate solution, c(K2Cr2O7) = 4 g/l in 50 % volumic fraction nitric acid solution. SIST EN 12678:2008
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