Speaker: Neville Taylor

Transcription

1 Paper: The importance of Stability Testing in Proficiency Testing Author: Vijay Padayachee Vijay Consulting cc PO Box 2707, Johannesburg, 2000, South Africa Phone: Fax: Speaker: Neville Taylor

2 This document is intended to explain the importance of Stability testing for Proficiency Testing Schemes.

3 Stability testing is validating that the proficiency testing sample is fit for purpose and will be able to identify errors in testing or calibration and not have false warnings due to unstable samples.

4 Stability claims reflects the ability of the PT sample to maintain consistent performance characteristics over time.

5 ISO/IEC17043:2010 for accreditation of proficiency testing schemes providers requires that the providers demonstrate both the homogeneity and the stability of proficiency testing samples.

6 The PT provider must be able to justify the claims that the Proficiency Testing sample has the ability to maintain consistent performance characteristics over times, and this can be done from experimental testing and data analysis that are appropriate for each proficiency testing measurand.

7 Stability characteristics of Proficiency Testing samples are affected by different internal and external factors such as preparation, packaging, storage conditions and handling procedures.

8 Shelf life stability testing Accelerated stability testing: In use stability Testing: Real-time stability testing: Transport stability testing:

9 Involves studies to determine the expiration date in its final packaging from the time of manufacture to the last day of usability. The testing should begin as soon as convenient after a batch is manufactured. The samples should be tested in a randomised order.

10 This process involves escalating the rate of chemical and physical damage of the Proficiency Testing sample by using overestimated environmental conditions such as light, temperature and humidity.

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12 The results from this study may be used to evaluate the influence of the design of the Proficiency Testing sample.

13 This process involves testing the Proficiency Testing sample over a period of time within its expiration date i.e. once the Proficiency sample has been prepared for testing. These studies are used to verify the amount of time in which the Proficiency Testing sample can retain its performance characteristics once opened. The testing should be done at the start and end of the shelf life.

14 This process involves exposing the Proficiency Testing sample to the recommended normal storage and in-use conditions, and assessing its robustness and stability under those conditions. The plan should extend beyond the expiry date.

15 This process involves exposing the Proficiency Testing sample to conditions designed to stimulate the extremes of environmental factors it may experience during the distribution process from the provider to the participant and then back to the recommended storage conditions before testing, sometimes referred as stress studies or flexi-testing.

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17 Results of the stress studies should be compared to baseline results from normal storage conditions to identify if any of the stability claims were affected by the stress conditions.

18 The process to establish the stability of a Proficiency Testing sample involves the following: Establish the operational definition of the stability for the Proficiency Testing sample. Establish a stability testing plan to generate experimental data Implement the plan Analyse and record the stability study claims

19 Theoretically, the stability of a Proficiency Testing sample is its ability to retain its properties and performance over a specified time period when stored under specified conditions.

20 The stability claim will demonstrate that the Proficiency Testing sample can meet all design input requirements at the start and end of a specified timeframe

21 The Proficiency Testing Provider should define the stability on the basis of ensuring that the key performance characteristics are met within predefined acceptance criteria throughout the claimed period.

22 In order to determine the timeframe over which a Proficiency Testing sample can be deemed stable, it is essential to establish the maximum allowable change for each stability characteristics before starting the study.

23 The acceptance criteria should come from the design input.

24 The Proficiency Testing sample stability study should use multiple samples in order to assess the performance across the method s analytical measurement range.

25 The experimental design and acceptance criteria of a stability claim should be documented in a stability testing plan which should include the following;

26 Identification of the Proficiency Testing sample Objectives of the studies to be performed Study protocol Acceptance criteria Number and identification of the Proficiency Testing sample batch to be tested Storage location of the Proficiency Testing sample

27 Specified environmental conditions Number of samples to be tested Measurement system(s) to be used Testing schedule Test volume Criteria of how the samples will be selected for the testing Testing procedure Data analysis procedure Procedure for handling outliers

28 All raw data must be retained. The final report should make reference to the study plan, any deviations from the plan, all results, a summary and a conclusion regarding the stability of the Proficiency testing sample.

29 Proficiency Testing sample stability claims are normally based on data derived from the real-time testing.

30 Stability testing validates the design of a Proficiency testing sample.