ILP (Inter Laboratory Practice)
Since 2005, UILI has been conducting ILP (Inter Laboratory Practice) as one of quality management in the global environmental chemical analysis field. Six tests have been implemented by 2011. Summary of past tests are shown on Table-1.
For evaluation, the median of reported values of participants are used as “certified value of CRM (Certified Referrence Material)” or “assigned values”. ISO/IEC 17043, APLAC (Asia Pacific Laboratory Accreditation Cooperation) T001 and ISO 13528 are adopted for statistical analysis. Results are shown by z scores and Youden plots with confidence ellipses.
The ILP Committee of UILI, JEMCA (Japan Environmental Measurement & Analysis Association) and VRS (Vereniging van Raadgevend Scheikundige Laboratoria) is in charge of statistical analysis, and report issuing for the Japanese and English version.
Taking into account the circumstances that analysis method diverse among countries, method in ILP is not instructed. However, participants are required to report their method on pretreatment and type of detection instrument used. Based on this information, we analyze and evaluate the difference of reported values depending on methods. In this point this test differs from the definition of “Proficiency Testing” of ISO/IEC ISO/IEC 17043, so we named “Inter Laboratory Practice”. Lots of attractive results we gained from 1st to 6th ILP which we couldn’t face in domestic inter-laboratory comparison tests. For instance, we found by statistical evaluation that different pretreatment when analyzing some metal causes a great differ in reported value.
As characteristic of chemical analysis, data are often exchanged at international trading scenes. We argue the benefits of this kind of program and result aspects in future of which mutual recognition system amongst global testing laboratories will become required.