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3 Traceability: Reference Materials
official or standard method for this purpose in the literature and draw its
flow chart.
• Literature
Example in suggested reading no. 3.
• Traceability to what?
Choose the last link in the chain of comparisons, which will be used as
reference. Preferably, it should be a base standard (an SI unit such as the
kilogram or mole). When the traceability chain cannot be extended as far as
such units, a standard with a value more distant from that held as true can be
used instead.
• Traceability paths
Explain the different available alternatives: use of primary standards, use of
sample standards, comparison with primary methods.
• Equipment calibration
Check that the equipment used to make the measurements (mass, volume,
atomic absorption, etc.) operates as expected.
• Method calibration
Find the relation between the cadmium concentration and the instrument's
absorbance reading. Determine derived analytical parameters (linear range,
limits of detection and quantitation).
• UseofaCRM
Are there any sea water matrix standards with certified cadmium contents?
How can they be used to realize traceability in the results of the CMP?
• Standards involved
What type of standard is required for each type of calibration? How are the
standards linked to SI units?
• Traceability chart
Draw a scheme showing the chains of comparisons whereby traceability of
the CMP can be realized. Include the different types of standards involved
(secondary, primary, chemical, base).
• State traceability
Write a report describing how traceability to the CMP was realized.
Seminar 3.3
Sample Standards: Preparation, Certification and Usage
• Learning objective
To demonstrate, via several examples, the different ways in which a matrix
CRM can be prepared, its homogeneity and stability assured, the certifying
campaign conducted, the standard supplied and used, and its documentation
completed.
• Sources
• CRM catalogues from different suppliers (NIST, BCR).
3 Traceability: Reference Materials
official or standard method for this purpose in the literature and draw its
flow chart.
• Literature
Example in suggested reading no. 3.
• Traceability to what?
Choose the last link in the chain of comparisons, which will be used as
reference. Preferably, it should be a base standard (an SI unit such as the
kilogram or mole). When the traceability chain cannot be extended as far as
such units, a standard with a value more distant from that held as true can be
used instead.
• Traceability paths
Explain the different available alternatives: use of primary standards, use of
sample standards, comparison with primary methods.
• Equipment calibration
Check that the equipment used to make the measurements (mass, volume,
atomic absorption, etc.) operates as expected.
• Method calibration
Find the relation between the cadmium concentration and the instrument's
absorbance reading. Determine derived analytical parameters (linear range,
limits of detection and quantitation).
• UseofaCRM
Are there any sea water matrix standards with certified cadmium contents?
How can they be used to realize traceability in the results of the CMP?
• Standards involved
What type of standard is required for each type of calibration? How are the
standards linked to SI units?
• Traceability chart
Draw a scheme showing the chains of comparisons whereby traceability of
the CMP can be realized. Include the different types of standards involved
(secondary, primary, chemical, base).
• State traceability
Write a report describing how traceability to the CMP was realized.
Seminar 3.3
Sample Standards: Preparation, Certification and Usage
• Learning objective
To demonstrate, via several examples, the different ways in which a matrix
CRM can be prepared, its homogeneity and stability assured, the certifying
campaign conducted, the standard supplied and used, and its documentation
completed.
• Sources
• CRM catalogues from different suppliers (NIST, BCR).