In the metrology of chemistry, an attempt is made to extend the traceability to the definition – mole – of the quantity belonging to the SI unit. However, in chemical measurements, many different factors impact the results and in the case of physical quantities, traceability can be extended to each quantity's measurement standard. Matrix effects, time and pH, which can have an impact on the results, introduce challenges to traceability, however. Validation proves that the desired measuring system produces correct results.
Traceability of one or several characteristic values can be proven by using certified comparison materials. These comparison materials are issued a certificate with measurement uncertainties corresponding to a calibration certificate. Matrix effects can also be taken into account in the comparison materials. Producers of certified reference materials can prove their competence with accreditation. Accreditation is based on ISO guide 34.