What is the difference between Primay and Secondry
Standard ?

Answer Posted / dixit kachhia

Reference Standard, Primary
A substance that has been shown by an extensive set of
analytical tests to be authentic material that should be of
high purity. This standard can be: (1) obtained from an
officially recognised source, or (2) prepared by independent
synthesis, or (3) obtained from existing production material
of high purity, or (4) prepared by further purification of
existing production material.
Reference Standard, Secondary
A substance of established quality and purity, as shown by
comparison to a primary reference standard, used as a
reference standard for routine laboratory analysis.

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