BS EN 901:2013 pdf download

BS EN 901:2013 pdf download.Chemicals used for treatment of water intended for human consumption -Sodium hypochlorite.
5.2.1.2 Principle
Sodium h.pochlorIte reacts with po(assftxn 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.
The titration may also be carried out potenhiometflcally by the aid of titration automates, in which case the addition of soluble starch is unnecessary.
5.2.1.3 Reagents
All reagents shall be of a recognised analytical grade and the water used shall conform to grade 3. as specified in EN ISO 3696:1995 (de..orwsed 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, odate-free, and dissolve in water and dibite to II.
5.2.1.3.2 AcetIc acid concentrated, of purity at least of mass fractIon 99 %
5.2.1.3.3 Sodium thiosulfate standard volLenetric solution, cNa2S2O3.5H2O) = 0,1 molll
Standard volumetflc solutions are commercially available, which might have to be diluted.
Allernatively, a standard volumetric solution may be prepared by the folowing procedure:
Dissolve 24.8 g NaS2O35l.4O In a 1 000 ml one-mark volumetflc flask in 0,75 I of water. After the temperature has equahsed. make up to the mark with water and nx thoroughly.
To standardise: 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(116 Kb3) 0,1 mnotfl). Place 200 ml of water in a 500 ml stoppered conical flask, add (2 ± 0.5)9 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 hydrochlonc 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 (I’,) of iodate used.
The actual concentration, c’, of the sodium thiosulfate standard volumetric solution (Na1S2O.5l-l1O). expressed in moles per litre is given by Fomiule (1):
c is the concentration, expressed in moles per litre, of the potassium iodate standard reference solution Ic(116K103)0.1 rnofl);
I is the volume, in millibtres, of the sodium thiosulfate standard volumetric solution used for the standardization (1’ = 10 ml);
I, is the volume, in mililitres. of potassium iodate standard reference solution used in the titration.
5.2.1.3.4 Starch solution, mass fraction of I %
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 poini. Keep the solution cool and use it within one week.
5.2.2.1.3 Reagents
Au reagents shall be of a recognised analytical grade and the water used shall have a conductivity of 0.056 aSicni (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(Na2CO3) 2 mmoLll with one volume of sodium hydrogen carbonate solution c(NaHCO3) = 0.75 mmolll.
5.2.2.1.3.2 Sulfuric acid solution c(H2S04) . 0.025 moUI regenerant solution.
5.2.2.1.3.3 Helium gas, high parity, for degassing eluant and regenerant solutions.
5.2.2.1.3.4 Sodium chlorate stock solution I gil.
Weigh, to the nearest 0,000 1 g. 0,255 1 g of NaCIO) 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 suppress.d conductivity detector
5.2.2.1.4.3 AnionIc column and pr.-column
Resin composed of 15 urn polystyreneldivinylbenzene substrate agglomerated with aneon exchange latex that has been aminaled,
5.2.2.1.4.4 Data loggeriplotter, able to record and display the chromatagrapc peak heights.
5.2.2.1.4.5 Generator of water (grade 1, EN ISO 3696:1995).
5.2.2.1.5 Chromatographlc conditions
— Eluant flow rate: 2 mIlmin
regenerant flow rate: 2,5 mllmin; full scale of conductivity: 30 mS; residual conductivity: C 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 (5.22.1.3.4) with the eluant solution (5.2.2.1.3.1). in accordance with Table 2.