Water quality -- Determination of pH

Document Number: NL ISO 10523 : 2010
Sector: Food Technology
TC: NL TC 147
ICS: 13.060.50
1.1 Field of application This method is applicable to all types of water and waste water samples in the range from pH 3 to pH 10. 1.2 Interferences The temperature, some gases and organic materials interfere with the pH-measurement. Suspended ma- terials in the Sample may Cause significant errors (Suspension effect). Wait for Sedimentation and only insert the electrodes in the clear fraction. Alterna- tively, an Ultrafiltrate tan be taken. When measuring sewage and some surface waters, there is a particu- larly high risk of smearing the electrodes or contami- nating the membranes and diaphragms with Oil, grease or other contaminants. In the case of reference electrodes, this tan be pre- vented (see 5.4, note 2). If precipitation takes place in the diaphragm, for example silver sulfide or Protein flocs, it will be necessary to form an electrolyte bridge between the Sample and the reference electrode with inert electrolytes, e.g. c(KN03) = 1 mol/l. Regular cleaning of the electrodes is necessaty (see 9 2) . 2010 English 25000.00 0 1727 1842 C NL ISO 10530 : 2010 NL TC 147 13.060.50 60.60 Food Technology Water quality -- Determination of dissolved sulfide -- Photometric method using methylene blue 1 .l Application range This International Standard specifies a photometric method for the determination of dissofved sulfide in water. The method is applicable to the determi- nation of dissolved sulfide in a mass concentration range from 0,04 mg/l to 1,5 mg/l. Higher concentrations may be determined by re- ducing and subsequently diluting the volume of the water Sample used. The method is applicable to waste water and natura1 waters requiring filtration. 1.2 Interferences The following ions do not interfere with the method as long as the mass concentrations specified below are not reached OY exceeded: Cyanide 2 rng/I Iodide 20 mg/l Thiosulfate 900 mg/l Thiocyanate 900 mg/1 Su Ifite 700 mg/1 When applying this procedure, the dctermination of the sulfide Portion from polysulfides will be incom- plete. Mass concentrations of carbon disulfide < IO mg/I and/or ethyl mercaptan < 1 n J/I do no1 interfere with the method. Waters which are not filterable according to clause 6 cannot be analysed by this method. In those cases sulfide which is easily liberated at pH 4 is determined. (An International Standard covering this is being prepared.) 2 "