3. Reference and certified materials

3.1 The various types of reference materials

This section summarizes the important aspects of reference materials (whether certified or not) for instrument calibration and method performance studies. The fundamental difference between reference materials (RMs) and certified reference materials (CRMs) is that some parameters or substances in CRMs are known with a high degree of accuracy and are guaranteed by the producer.

There are four main types of reference material.

• Pure substances or solutions: used for calibration and/or identification, or for testing part or all of an analytical procedure. These materials are characterized or certified by establishing the maximum quantity, in mass fractions, of impurities remaining...