A silicon metal quality-control standard preparation by means of collaborative trials of Brazilian laboratories

A powdered silicon metal material was prepared as a quality-control standard to provide the Brazilian quality-control laboratories with a means to verify the quality of their results, when determining Ca, Al, Fe, Mn and Ti present as impurities. The material was prepared and its homogeneity tested using one-way ANOVA with an ICP-OES analytical technique. The participating laboratories in the first collaborative trial were requested to use their routine procedures that included XRF, ICP-OES and FAAS techniques to analyse the distributed samples. The statistical analysis results showed that the interlaboratory variabilities were very high. By implementing a suggested protocol to put the solid sample into a solution, the participating laboratories showed better performances in the second run. By attributing values to the prepared material the analytes' results were obtained in a new collaborative trial. Statistically the data were evaluated with two-way ANOVA. The values and their associated uncertainties included inhomogeneity and characterisation uncertainties.