Wednesday, 30 July, 2014

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METHOD VALIDATION

Purpose of method validation: to adequately demonstrate that a particular method is fit for its intended purpose.
According to ISO / IEC 17025, “Validation is the confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled.” (ISO / IEC 17025 is the guideline used by assessment bodies when auditing laboratories).

This is a clause that indicates one of the key requirements for compliance of laboratories that are accredited or seeking accreditation. Without method validation, an accreditation body will not consider assessment of an analysis since the ability of the laboratory is brought into question for the particular analysis.

Some aspects of method validation include the following:
  • Accuracy
  • Precision
  • Ruggedness
  • Robustness
  • Range
  • Linearity
  • Uncertainty of measurement 
Wherever applicable these factors must be taken into account. Method validation gives the laboratory confidence to defend its analytical results when disputes occur.

COMMISONING OF LABORATORIES

Laboratories can be commissioned to include some of the following requirements:
  • Location of the laboratory
  • Design and layout
  • Equipment requirements and procurement
  • Consumable requirements and procurement
  • Assistance with recruitment of appropriate staff
  • Training of staff if required
  • Compilation of standard operating procedures

ASSESSMENTS

Prior to the laboratory being assessed by an accreditation body, the laboratory can be assessed for compliance to the technical requirements of ISO / IEC 17025. A vertical assessment can be carried out where a report that has been submitted to a client is chosen and the validity of the information on the report is traced, for example the analyst that conducted the test, training of the analyst, equipment used, calibration of the equipment etc. Any weakness in the system is raised as an audit finding. This helps the laboratory improve on its quality system. Also horizontal assessments can be done in terms of witnessing exercises. A particular test method is selected and the analyst is witnessed whilst the determination is carried out according to a standard operating procedure. If there are any deviations to the standard operating procedure audit findings are raised. Vertical and horizontal audits ultimately assist laboratories with continuous improvement.

BIAS TESTING

Bias testing is carried out according to ISO/IEC 13909 -8:2001 (Hard coal and Coke -Mechanical sampling: Methods of testing for bias). The reasons for testing for bias might be for contractual requirements or diagnostic purposes. It should be noted that no system whether it is sampling, sample preparation or analysis is completely free of bias. Instead the maximum tolerable bias should ascertained at the outset of bias testing