Proficiency Testing in Industrial & Commercial Laboratories

Type 1 (CRM Based)

In this type of test Thistle QA will source certified reference materials from a commercial supplier suitable for analysis by the clients’ analytical methodology where a number of elements have well established values. The results of analysis carried out on these materials over an agreed review period will be evaluated by a number of statistical procedures and the performance of the laboratory assessed by the proximity to the certified value (“z” score) the percentage deviation and the precision of test results.

Type 2 (Specification Testing)

Certain products need to meet a given specification to be acceptable in the market or to meet a particular quality parameter e.g. impurities must lie within a specified range. Special High Grade (SHG) zinc is an example of such a commodity. Thistle QA will design an individual test programme and carry out statistical analysis of data produced by a laboratory to demonstrate that minor elemental components in current production batches are part of the same data set as those of the standard selected by the client and whose values are known to be acceptable by consensus.

Type 3 (Inter-laboratory Testing)

With the permission of individual laboratories and when sufficient participants’ results become available tables will be published comparing individual laboratory performance with that of the other participants for benchmarking purposes. In publishing these data individual laboratories are not identified other than by a code number known only to the laboratory concerned and Thistle QA

Type 4 (Method Validation)

Analysis of a material of known composition, not only of the major components but also those components which are not typically analysed for, is valuable in providing data for use in correcting for interferences in instruments with multi element capability. Once this data have been verified by proficiency testing the applicability of various analytical strategies can be compared. An example might be to compare results obtained using the high speed capability of multi-element XRF analysis when compared with those obtained from ICP instruments involving extended sample preparation times.

Type 5 (QA Report Validation)

Should a laboratory already operate a thorough and comprehensive QC system that complies with good quality management practices Thistle QA will review the data generated and issue a quality audit report based on verification of the conclusions drawn. It is our experience that such independent verification of results produced is a valuable marketing tool in a highly competitive environment.