pHMeasurement is a relative measurement that only indicates the relationship between a standard solution and an unknown solutionpHDifference, in actual measurement, it is necessary to calibrate regularly with standard buffer solution. Therefore, in order to achieve consistency in measurement values, it is necessary to establishpHScale.PH standardThe degree range is set as0～14pH，pHThe magnitude of the scale is determined by the reference buffer solutionpHsValue determination. Therefore,pHThe meaning of scale can be expressed as: based onpHDefinition, in0～14pHSelect several options within the scopepHBuffer solution aspHThe fixed points of the scale are measured using the most accurate method possible with contemporary technology to determine their accuracypHsValue. There are two types availablepHScale, i.e. multiple benchmarkspHScale and single referencepHScale, China adopts multiple benchmarkspHsScale. Six reference buffer solutions0～95℃ofpHsSee table for values(1).
table(1) Six reference buffer solutionspHsvalue