ISO 23496:2019 pdf download

ISO 23496:2019 pdf download

ISO 23496:2019 pdf download.Determination of pH value – Reference buffer solutions for the calibration of pH measuring equipment
1 Scope
This document specifies reference buffer solutions fo r the calibratio n of pH measuring equipme nt.
2 Normative refer enc es
The following documents are referred to in the text in suc h a way that some or all of their content constitutes requirements of this document. For dated references, only the edit ion cited applies. For und ated references, the latest edition of the referenced document (including any amendments ] applies.
ISO 4793, Laboratory sintered filters – Porosity grading, classification and designation
ISO 19396-1, Paints and varnishes – Determination of pH value – Part 1: pH electrodes with glass membrane
ISO and units – Part 9: Physical chemistry and molecular physics
3 Terms and de finitions
For the purpo ses of this document, the terms and definitions given in ISO 80000-9 and the following apply.
ISO and I EC maintain terminological databases for use in standardization at the following addresses:
3.1 pH
ISO Online browsing platform: availab le at
IEC Electropedia: available at ht tp:,L/,L measure for the acidic or bas ic character of an aqueous solution
Note 1 to entry: Notation of pH: the p ” and the ” H ” are upright on one line.
Note 2 to entry: The acidic character is determined by the activity of the existing “hydrogen ions ”.
4 Ba sic information
4.1 General
Reference buffer so l utions are prepared using primary or secondary reference materials. The pH values of the reference buffer solutions are determined using the methods described The pH value of a reference buffer solution and the associated uncertainty of measurement are documented in a calibration certificate as the result of calibration. pH values of primary reference buffer solutions form the basis of pH measurements in practice and are generally det erm ined by nationa l metrology instit utes. Secondary reference buffer sol utions are commercially available. The reference buffer sol utions prepared according to the methods described as a material measure of the pH value.
4.2 The pH value based upon the activity of single ions according to the formula cannot be measured. The pH value is assigned to reference buff er solutions outlined in Iab.J.e…l . This is achieved using an el ectroc hemical method of m eas ur e ment that is based on the thermodynamic dependence of the potential of the platinum/hyd rogen electrode on the h ydrogen ion activity. Through the use of cells without transference, diffusion voltages arising from liquid junctions do not appear and the refore do not need to be considered when calculating the vol tage of the cell.