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Analytical Standards


Introduction

Standards are materials containing a known concentration of an analyte. They provide a reference to determine unknown concentrations or to calibrate analytical instruments.

The accuracy of an analytical measurement is how close a result comes to the true value. Determining the accuracy of a measurement usually requires calibration of the analytical method with a known standard. This is often done with standards of several concentrations to make a calibration or working curve.


Primary Standards

A primary standard is a reagent that is extremely pure, stable, has no waters of hydration, and has a high molecular weight.

Some primary standards for titration of acids:

Some primary standards for titration of bases:

Some primary standards for redox titrations:


Secondary Standards

A secondary standard is a standard that is prepared in the laboratory for a specific analysis. It is usually standardized against a primary standard.


NIST Standard Reference Materials

The National Institute of Standards and Technology (NIST) provide a wide variety of standard reference materials (SRMs) for validating and calibrating analytical methods. Some examples of SRMs:

for chemical composition

for physical properties

for engineering materials