4 Metrological Traceability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1
Traceability and the Comparability of Results . . . . . . . . . . . . . 37
4.1.1
The Standard Should Mimic the Measured
Quantity to the Best Extent . . . . . . . . . . . . . . . . . . . 39
4.2
General Requirements for Metrological Traceability . . . . . . . . 45
4.3
Measurement Traceability Over Time . . . . . . . . . . . . . . . . . . . 46
4.4
Compliance with the Requirements of the Reference
Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.5
Metrological Traceability in Practice . . . . . . . . . . . . . . . . . . . 47
4.6
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.1
Bracketing Over a Range of Concentrations . . . . . . . . . . . . . . 57
5.2
Evaluation of Recovery with Reference Materials . . . . . . . . . . 58
5.3
Method of Standard Addition . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.4
The Advantages of the Standard Addition Method . . . . . . . . . 60
5.5
Limitations of the Standard Addition Method . . . . . . . . . . . . . 60
5.6
The Method of the Internal Standard . . . . . . . . . . . . . . . . . . . 61
5.7
Internal Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.8
The Quality of Calibration of Analytical Procedure . . . . . . . . . 63
6 Reference Materials in Chemical Measurements . . . . . . . . . . . . . . . 65
6.1
Basic Definitions and Requirements . . . . . . . . . . . . . . . . . . . . 66
6.2
Production of Reference Materials . . . . . . . . . . . . . . . . . . . . . 70
6.3
Types of Reference Materials . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.4
Chemical Substances of a Given Purity . . . . . . . . . . . . . . . . . 73
6.5
Matrix Reference Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.6
Applicability of Reference Materials . . . . . . . . . . . . . . . . . . . 73
6.7
Selection of Reference Materials . . . . . . . . . . . . . . . . . . . . . . 75
6.8
The Type of Reference Material Versus the Type
of Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.9
The Content of the Substance to Be Determined
in the Reference Material and the Sample . . . . . . . . . . . . . . . . 77
6.10 The Uncertainty of the Certified Value and the Expanded
Uncertainty of the Measurement Result . . . . . . . . . . . . . . . . . 78
6.11 Proper Use of Reference Materials . . . . . . . . . . . . . . . . . . . . . 80
6.12 The Reference Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.13 The Shelf Life of Reference Materials . . . . . . . . . . . . . . . . . . 81
6.14 The Use of Certified Reference Materials for Ensuring
the Traceability of the Result . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.15 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
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4.1
Traceability and the Comparability of Results . . . . . . . . . . . . . 37
4.1.1
The Standard Should Mimic the Measured
Quantity to the Best Extent . . . . . . . . . . . . . . . . . . . 39
4.2
General Requirements for Metrological Traceability . . . . . . . . 45
4.3
Measurement Traceability Over Time . . . . . . . . . . . . . . . . . . . 46
4.4
Compliance with the Requirements of the Reference
Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.5
Metrological Traceability in Practice . . . . . . . . . . . . . . . . . . . 47
4.6
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.1
Bracketing Over a Range of Concentrations . . . . . . . . . . . . . . 57
5.2
Evaluation of Recovery with Reference Materials . . . . . . . . . . 58
5.3
Method of Standard Addition . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.4
The Advantages of the Standard Addition Method . . . . . . . . . 60
5.5
Limitations of the Standard Addition Method . . . . . . . . . . . . . 60
5.6
The Method of the Internal Standard . . . . . . . . . . . . . . . . . . . 61
5.7
Internal Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.8
The Quality of Calibration of Analytical Procedure . . . . . . . . . 63
6 Reference Materials in Chemical Measurements . . . . . . . . . . . . . . . 65
6.1
Basic Definitions and Requirements . . . . . . . . . . . . . . . . . . . . 66
6.2
Production of Reference Materials . . . . . . . . . . . . . . . . . . . . . 70
6.3
Types of Reference Materials . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.4
Chemical Substances of a Given Purity . . . . . . . . . . . . . . . . . 73
6.5
Matrix Reference Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.6
Applicability of Reference Materials . . . . . . . . . . . . . . . . . . . 73
6.7
Selection of Reference Materials . . . . . . . . . . . . . . . . . . . . . . 75
6.8
The Type of Reference Material Versus the Type
of Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.9
The Content of the Substance to Be Determined
in the Reference Material and the Sample . . . . . . . . . . . . . . . . 77
6.10 The Uncertainty of the Certified Value and the Expanded
Uncertainty of the Measurement Result . . . . . . . . . . . . . . . . . 78
6.11 Proper Use of Reference Materials . . . . . . . . . . . . . . . . . . . . . 80
6.12 The Reference Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.13 The Shelf Life of Reference Materials . . . . . . . . . . . . . . . . . . 81
6.14 The Use of Certified Reference Materials for Ensuring
the Traceability of the Result . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.15 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
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Contents