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Volume I - 5.6 Measurement Traceability

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ORA Laboratory Policies

Food and Drug Administration

DOCUMENT NO.:
ORA-LAB.QM

VERSION NO.:1.9

ORA Laboratory Manual of Quality Policies

EFFECTIVE DATE:
10-01-03
REVISED:
01-22-13

5.6.1 General

The laboratory equipment is calibrated before being placed into service, as scheduled and following repairs. Procedures for equipment calibration are provided in Volume II, Section 2, ORA-LAB.5.5 Equipment.

5.6.2 Specific Requirements

5.6.2.1  Calibration – Requirements for Contracting Metrologists

5.6.2.1.1 Measurement Traceability

The program for calibration of equipment demands that calibrations and measurements made by the laboratory are traceable to the International System of Units. The scheduling of calibration activities is defined in Volume II, Section 2, ORA-LAB.5.5 Equipment, Table 2. 

Contracting metrologists providing services to ORA laboratories are to provide evidence of measurement traceability of its own measurement standards and measuring instrument to the SI.  This is done by means of an unbroken chain of calibration or comparisons linking them to primary standards of the SI units of measurement. Such primary standards are those used by national measurement standards.

The measurement traceability to SI units may be achieved by measurements related to national measurement standards. National measurement standards may be used as primary standards that are primary realizations of the SI units or agreed representations of SI units. National measurement standards based on fundamental physical constants, or standards calibrated by another national metrological institute may be use as primary standards.

Contracting metrologists providing services to ORA laboratories are to provide documentation demonstrating measurement capability and competence to perform the calibration services requested by ORA laboratories.

Calibration certificates issued by contracting metrologists are to include the measurement results, including the measurement uncertainty and a statement of conformance with an identified metrological specification.

5.6.2.1.2.1 Non-traceability of reference standards to SI units

Calibrations that cannot provide strict measurement traceability to SI units are conducted such that the calibration results can provide confidence in the measurements made in the course of the analyses.  Traceability alternatives to SI units are described in the procedure in Volume II, Section 2, ORA-LAB.5.6 Measurement Traceability.

5.6.2.1.2.2 Interlaboratory comparisons

ORA laboratories participate in FDA’s National Check Sample Program, the AOAC Standard Microbiology Proficiency Testing Program, and other national or international proficiency programs, as applicable.

5.6.2.2 Testing 

5.6.2.2.1 Testing and calibration activities

The requirements of Volume I, Subsection 5.6.2.1 Calibration-Requirements for Contracting Metrologists are included in the laboratory’s calibration program for equipment that has a significant contribution from its calibration to the total measurement uncertainty.  Contributions are considered significant if they are greater than a fifth of the largest contributor.

The measurement of uncertainty is determined and recorded according to Volume II, Section 2, ORA-LAB.5.4.6, Estimation of Uncertainty of Measurement.

Equipment that does not contribute appreciably to the total uncertainty of the test result is exempt from the activities described in Volume I, Subsection 5.6.2.1 Calibration-Requirements for Contracting Metrologists.

5.6.2.2.2 Non-traceability to SI Units

Where measurement traceability for testing and calibration activities to SI units is not possible, the policies stated in Volume I, subsection 5.6.2.1 Calibration-Requirements for Contracting Metrologists are followed.

5.6.3 Reference Standards and Reference Materials

5.6.3.1 Reference Standards

The laboratory calibrates its reference standards. Details are included in Volume II, Section 2, ORA-LAB.5.5 Equipment.

A contracting metrologist who is to provide measurement traceability as described in Volume I, subsection 5.6.2.1 calibrates the reference standards.

The reference standards are used for calibration only.

5.6.3.2 Reference Materials

A reference material is a homogenous and well characterized substance used for standardization of equipment used in the testing process. Reference materials are traceable to national or international standard reference materials (SRMs), such as National Institute of Standards and Technology (NIST), or certified reference materials (CRMs) from competent suppliers of reference materials.

The measurement integrity of internal reference materials generated by the laboratory is evaluated against either standard reference materials or certified reference materials from an independent source when it is technically and economically possible.

5.6.3.3 Intermediate Confirmation of Calibration Status

Metrological confirmation for reference standards and reference materials included in the calibration program is conducted according to a schedule addressed in the procedure in Volume II, Section 2, ORA-LAB.5.5 Equipment. The confirmation is conducted to maintain confidence in the calibration status of reference standards and reference materials.

5.6.3.4 Transport and Storage

The procedure found in Volume II, Section 2, ORA-LAB.5.6 Measurement Traceability, addresses the safe handling, transport, storage and use of reference standards and reference materials.  These activities are established in order to prevent contamination, deterioration, and to protect the integrity of reference standards and reference materials.

Related Procedures