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KMID : 1059519980420040432
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Journal of the Korean Chemical Society
1998 Volume.42 No. 4 p.432 ~ p.442
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Hwashim Lee, Myungsoo Kim, Jinbok Lee, Sanghyup Oh
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Lee Hwa-Shim
Kim Myung-Soo
Lee Jin-Bok
Oh Sang-Hyup
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Abstract
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Since the definition of pH, pH=-IogaH 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 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 ±0.005 pH unit.
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