INTER-LABORATORY COMPARISON OF PLANT ANALYSIS ACCURACY IN MEXICO

Abstract

Laboratories seeking accreditation based on norm ISO 17025 are requested to satisfy several requirements such as: traceability of measurements (i.e., the use of certified reference material linked to SI units), participation in inter-laboratory comparison or proficiency testing programs, and determination of the uncertainty of the measurements. One of the objective of the present work was to evaluate the accuracy of analytical measurements conducted by Mexican soil and plant analytical facilities, using certified reference material as recommended by the metrological methods. The statistics used to evaluate the accuracy was the Mean Square Error as recommended by The Mexico's Metrological National Center (CENAM). Most laboratories did not produce reliable results. It is important to have long term programs like this and more reference materials available to achieve better accuracy. The results of the intercomparison exercises allowed to identify the laboratories that generate reliable results.