Meeting the measurement uncertainty and traceability requirements of ISO/AEC standard 17025 in chemical analysis

Complying with the resource requirements of ISO/IEC 17025:2017 in Indonesian calibration and testing laboratories: current challenges and future directions

Compliance with all the requirements in the ISO/IEC 17025:2017 is crucial for testing and calibration laboratories in assuring the quality of measurement conducted in their laboratories. The latest version of the ISO/IEC 17025:2017 presents a different structure compared to the previous version, ISO/IEC 17025:2005. Therefore, amendments in the quality documents and the operational procedures in the laboratories are urgently required. However, not all laboratories' personnel understand this new standard and know how to implement or incorporate this new version standard with their old version documents and operational procedures. It causes a problem for the testing and calibration laboratories, especially in Indonesia. This study is expected to provide enlightenment and hints for the laboratories struggling to comply with the ISO/IEC 17025:2017.

Standardisation of data from real-time quantitative PCR methods - evaluation of outliers and comparison of calibration curves

Background

As real-time quantitative PCR (RT-QPCR) is increasingly being relied upon for the enforcement of legislation and regulations dependent upon the trace detection of DNA, focus has increased on the quality issues related to the technique. Recent work has focused on the identification of factors that contribute towards significant measurement uncertainty in the real-time quantitative PCR technique, through investigation of the experimental design and operating procedure. However, measurement uncertainty contributions made during the data analysis procedure have not been studied in detail. This paper presents two additional approaches for standardising data analysis through the novel application of statistical methods to RT-QPCR, in order to minimise potential uncertainty in results.

Results

Experimental data was generated in order to develop the two aspects of data handling and analysis that can contribute towards measurement uncertainty in results. This paper describes preliminary aspects in standardising data through the application of statistical techniques to the area of RT-QPCR. The first aspect concerns the statistical identification and subsequent handling of outlying values arising from RT-QPCR, and discusses the implementation of ISO guidelines in relation to acceptance or rejection of outlying values. The second aspect relates to the development of an objective statistical test for the comparison of calibration curves.

Conclusion

The preliminary statistical tests for outlying values and comparisons between calibration curves can be applied using basic functions found in standard spreadsheet software. These two aspects emphasise that the comparability of results arising from RT-QPCR needs further refinement and development at the data-handling phase. The implementation of standardised approaches to data analysis should further help minimise variation due to subjective judgements. The aspects described in this paper will help contribute towards the development of a set of best practice guidelines regarding standardising handling and interpretation of data arising from RT-QPCR experiments.

Uncertainty of Measurement: Approaches and Open Problems

Despite of exhaustive literature information, analysts are still fronting serious problems in estimating the uncertainty of measurement (UOM), mainly because of the intrinsic difficulties in choosing an appropriate approach and/or of an inadequate background in statistics and metrology fundamentals. Sometimes, additional problems, at present under debate, make their efforts even more stressful. In this paper, attention is mainly paid to intra-laboratory estimation of UOM, the most frequent situation. After a short re-examination of the existing UOM approaches, some applicative problems are discussed in the light of the most representative literature information.