The Establishment And Use Of A Reference Material As A Control Sample

The production of reliable analytical data is dependent on a range of quality control procedures. One of the critical components of a robust quality assurance program is the ability to demonstrate the comparison of results achieved to a previously "benchmarked sample." The use of a validated internal reference sample with a similar matrix as that of samples routinely analyzed is the preferred option. However, due to cost considerations and the commercial availability of suitable reference material, this is often not possible.This paper describes our experience in establishing reference control sample of pine needles (spp. Pinus patula) in collaboration with Wageningen Evaluating Programmes for Analytical Laboratories (WEPAL) based at the Wageningen University in the Netherlands.The sample was analyzed for total concentrations of B, Fe, Cu, Zn, Mn, P, Ca, Mg, K, Na and N. The results achieved are presented in comparison to the consensus values achieved by the IPE (International Plant Analytical Exchange) program. The data was analyzed and the group statistics (mean, standard deviation and coefficients of variation) were determined for each element.dIn general the Standard Deviation values for the "intra laboratory" analyses were lower than the "inter laboratory" values achieved. The wide range of analytical methods considered in the "inter laboratory" comparison will most likely account for this difference.