Quality assurance and control in a plant analysis laboratory

Abstract The plant samples are mineralized using the CII reference method, then K, Ca, Mg, Na, P, B, Fe, Cu, Mn, Zn, and Al are determined with a multi‐channel AES‐Inductively coupled plasma (ICP) emission spectrometer. The measurement protocol is based on the repeatability and the precision of the whole of these elements: the calibration is done again every 20 samples. The results computation takes the shift into account. When a complex 10 mg/L solution is analyzed for six hours (120 measures), the variation coefficients are less than 2.5%. The routine analyses control is done introducing internal reference samples (palm tree, pineapple, and maize leaves powders). Control charts are drawn to check the global quality, including the mineralization and the instrumental measure. The yearly variation coefficients arc less than 6%, except for Cu and Zn in the ananas sample. The laboratory proficiency is tested with the International Plant Exchange program. Our results are very close to the published medians, e...