Studies on the Standardization of pH Measurement System

pH 측정 시스템의 표준화에 관한 연구

  • Lee, Hwa Shim (Electrochemistry Laboratory, Korea Research Institute of Standards and Science) ;
  • Kim, Myung Soo (Electrochemistry Laboratory, Korea Research Institute of Standards and Science) ;
  • Kim, Jin Bok (Electrochemistry Laboratory, Korea Research Institute of Standards and Science) ;
  • Oh, Sang Hyup (Electrochemistry Laboratory, Korea Research Institute of Standards and Science)
  • 이화심 (한국표준과학연구원 전기화학그룹) ;
  • 김명수 (한국표준과학연구원 전기화학그룹) ;
  • 김진복 (한국표준과학연구원 전기화학그룹) ;
  • 오상협 (한국표준과학연구원 전기화학그룹)
  • Published : 19980800

Abstract

Since the definition of pH, $pH=-Ioga_H$ is based on a single ion activity, pH values can not be determined with measurement itself, but require an approximation method. They are derived from EMF measurement of a liquid junction free cell using hydrogen and Ag/AgCl electrodes. Primary standard materials with certified pH values can be obtained with this approximation method. Standard buffer solutions are used to calibrate pH meters. Thus the accuracy of the pH values of standard buffer solutions limits the reliability of measured pH values can be obtained with this approximation method. Standard buffer solution are used to calibrate pH meters. Thus the accuracy of the pH values of standard buffer solutions limits the reliability of measured pH values of sample solutions. To certify the pH values, we have established the system for the primary standard measurement and certified the pH of buffer solutions in the range of 1.6∼12.5 pH unit within uncertainty of ${\pm}0.005$ pH unit.

Keywords

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