Proficiency Testing PT

Over the past decade, a major trend has been the development of the use of proficiency testing (PT) or evaluation materials (Fox 2000). PT materials are a type of reference material, which aid in assessment of analytical laboratory measurement quality. There will be an increased use of such materials as part of laboratory accreditation programs and other new quality assurance efforts, including internal audits. At the same time, a number of providers have used PT schemes to produce a form of RM intended to meet the ever-growing need for RMs required for routine QC use (Jenks 1995,1997). 

The previous chapters of this book have discussed the many activities which laboratories undertake to help ensure the quality of the analytical results that are produced. There are many aspects of quality assurance and quality control that analysts carry out on a day-to-day basis to help them produce reliable results. Control charts are used to monitor method performance and identify when problems have arisen, and Certified Reference Materials are used to evaluate any bias in the results produced. These activities are sometimes referred to as internal quality control (IQC). In addition to all of these activities, it is extremely useful for laboratories to obtain an independent check of their performance and to be able to compare their performance with that of other laboratories carrying out similar types of analyses. This is achieved by taking part in interlaboratory studies. There are two main types of interlaboratory studies, namely proficiency testing (PT) schemes and collaborative studies (also known as collaborative trials). 

Participation in Proficiency Testing (PT) schemes/interlaboratory comparisons and review of data... 

To monitor the laboratory performance against both its own requirements and the norms of peer laboratories there is a need for intercomparison of laboratory results. This is usually done by participating in proficiency testing (PT), i.e. an external quality assessment. In this way, the laboratory performance at national or international level are monitored and, furthermore, the reproducibility is highlighted. 

We also can take suitable data from a proficiency test (PT). In this case the laboratory must have participated in the PT successfully. We also have to consider, if the PT covered all relevant uncertainty components and steps of analysis. This includes e.g. if the matrix of the PT sample was similar to routine samples. If this is the case, we again calculate U from 2 Sr. 

The third type of interlaboratory tests is proficiency testing (PT) for laboratories. The objective here is to get an indication of the performance of the laboratoiy. The laboratory should work under routine conditions to get a realistic indication of its performance. A PT can not only be a help for the laboratoiy to improve its capabilities, but also can be used by customers or regulatory bodies for the selection of qualified laboratories. 

Participance in Proficiency Testing Schemes Proficiency testing (PT) is the periodic assessment of the competency or the analytical performance of individual participating laboratories [23]. An independent coordinator distributes individual test portions of a typical uniform test material. The participating laboratories analyze the materials by their method of choice and return the results to the coordinator. Test results obtained by different laboratories are subsequently compared with each other and the performance of each participant evaluated based on a single competency score [64,107]. International harmonized protocols exist for the organization of PT schemes [59,60,64,69,79]. 

Eurachem Guide (2000), Selection, Use and Interpretation of Proficiency Testing (PT) Schemes by Laboratories, available http //www.eurachem.org. 

Results of a trial United Kingdom proficient testing (PT) scheme using stack-emission gases... 

Fig. 2 Summary of results of the National Physical Laboratory Source Testing Association (NPL/STA) proficiency testing (PT) scheme for gaseous analysis...

Provide Proficiency Testing (PT) to field laboratories to establish comparability and reliability Develop and validate analytical methods in the field of responsibility... 

The need to carry out both QA and QC in order to achieve the expected quality of analytical results immediately generates the requirement for clearly defined performance criteria. These criteria enable comparability to be achieved via the traceability of analytical results to national or international standards along an unbroken chain of comparisons. Validation is the central task in the development of any analytical method whose capabilities in specific applications can be assessed with the aid of measurement uncertainty. Finally, proficiency testing (PT) serves to demonstrate comparability in terms of the scatter of the results.3... 

Before the designation, the laboratories developed their laboratory methods for testing, constructed and made operational their laboratory quality system and obtained its accreditation, and continued the participation and successful performance in the OPCW proficiency tests (PT). Analytical methods in particular and a certain level of quality assurance systems have existed in the laboratories, involved often in research, well before their designation. Participation in the international interlaboratory... 

External laboratory QC involves reference help from other laboratories and participation in national or international interlaboratory sample and data exchange programs such as Proficiency Testing (PT). Such programs may involve ... 

A Proficiency Test (PT) is defined as the study of laboratory performance by means of ongoing interlaboratory test comparisons . It is also known as an external quality assessment scheme, external laboratory performance check or external quality assurance (EQA). There are many such schemes run by independent external bodies for different analytes in a variety of matrices. Evidence in published papers shows that the performance of analytical laboratories improves as a result of participating in Proficiency Testing schemes and the betw een-laboratory precision can improve, sometimes dramatically. This is especially true in the early years of participation. 

Ion-selective electrodes (ISEs) represent the current primary methodology in the quantification of S-Li [11-13], Moreover, ISE modules are parts of large and fully automated clinical chemistry analysers. In practice, the validation parameters are most often chosen in terms of judging the acceptability of the new measurement system for daily use. For this reason, the first approach was to study whether the detected imprecision fulfilled the desired analytical quality specifications. Secondly, proficiency testing (PT) results from past samples were of great value in predicting future bias. The identity of the three ISE methods was evaluated using patient samples. The analytical performance was checked after 6 months routine use. Without any exception, method validations always mean an extra economical burden. Therefore, the validation parameters chosen and processed have to be considered carefully. 

Standardization of immunochemical methods will be needed for their widespread usage in different countries and laboratories. This will include SOPs (standard operating procedures), GLP (good laboratory practice), and participation in proficiency tests (PTs) that will be comparable to those carried out routinely for conventional analysis, but with adaptations to tailor them for immunochemical analysis. 

For this aim, three proficiency testing (PT) campaigns were organized within the SWIFT-WFD project, mainly dedicated to the determination of the list of priority pollutants annexed to the WFD. The SWIFT-WFD PT campaigns, one per year for three years, were organized on 17 reference materials (RMs) including 5 matrix RMs at natural concentration levels, 3 at low fortified concentration levels, 4 at fortified concentration levels, and 5 multi-analyte blind standard solutions, targeting the analysis of... 

Participation in proficiency testing (PT) programmes is included as part of the requirements that the laboratories must fulfil in order to demonstrate their competences in analysing relevant physico-chemical or chemical measurands under the WED. 

When information on the stability of analyte in matrix during typical conditions of storage is unavailable from the literature or from proficiency testing (PT) providers, such as the food analysis proficiency assessment scheme (PAPAS), this information shouid be developed in the laboratory as part of the method development and validation. However, a study to obtain information on stability of the analyte first requires the availability of a validated method if results are to be considered reliable. When a method is being developed to introduce a test capability for a new analyte into the laboratory, the new... 

Given that laboratories accredited to ISO 17025 are encouraged to participate in proficiency testing (PT) programs when available, historical data from PT participation can be used to estimate an individual laboratory s uncertainty. The approaches to using PT data to calculate uncertainties vary Horwitz models," modifications of the ISO 5725-2 approach," and propagation of uncertainty models with variations depending on reliability of PT participants ... 

A key feature of the MRA is the development of a BIPM key comparison database (KCDB), which includes the results of key and supplementary comparisons (KCs) and the calibration and measurement capabilities (CMCs) of the NMI signatories to the MRA. Key comparisons are high-level interlaboratory comparisons of the standards or measurement procedures of the participating institutes. The scheme for organizing such comparisons is shown in Figure 3. The comparisons are operated in the same way as proficiency testing (PT) schemes, i.e.. 

Laboratories that are accredited to ISO 17025, rather than the well-established ISO 9000 series, are using RMs and CRMs more often and are signing up for proficiency testing (PT). ISO 17025 is the standard that provides the international aspect to any laboratory measurement process and provides the control framework to assist the production of comparable measurements. ILAC (International Laboratory Accreditation Co-operation) harmonises laboratory accreditation procedures. ISO 17025 plays an important role in international traceability and in the requirements for an internationally agreed suitable CRM. 

The performance of the GFPC and LSC methods for the measurement of gross alpha and beta activity in water was evaluated by participating in Proficiency Tests (PT) organized by Instituto de Radioprotefao e Dosimetria IRD/CNEN, which is available on a routine basis three times per year. The results obtained for the measurement of gross alpha... 

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