Reference Standard is highly characterized specimen of chemical .....
This statement may be just a definition. It defines that
Reference Standard : highly characterized specimen of chemical 标准物质 : 理化特征明确的化学品
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For information:
In metrology, reference material is defined as follows (from “International Vocabulary of Basic and General Terms in Metrology”)
5.13 reference material, RM material, sufficiently homogeneous and stable with respect to one or more specified quantities, used for the calibration of a measuring system, or for the assessment of a measurement procedure, or for assigning values and measurement uncertainties to quantities of the same kind for other materials
5.14 certified reference material, CRM reference material, accompanied by an authenticated certificate, having for each specified quantity a value, measurement uncertainty, and stated metrological traceability chain
I think that the reference standard in chemistry may be same as the reference material in metrology.