Preparation of in-house reference material of Fe, Ca, Ni, and Si in carbon samples from an aluminum industrial facility and the results of a proficiency test
This study presents the preparation of reference material for Fe, Ca, Ni, and Si to ensure the quality of the analysis of these elements in routine samples of carbonaceous materials in the aluminum industry. The sample was fractioned and bottled for homogeneity and stability studies before being shipped to interlaboratory certification. We then sent a bottle to each of the seven participating laboratories to determine the reference values. The results of concentration for Fe, Ca, Ni, and Si after outlier exclusion were 589.1 ± 25.3, 142.9 ± 12.0, 178.1 ± 9.3, and 134.2 ± 6.6 ppm, respectively. Lastly, we applied a technique called z-score to evaluate the performance of the participating laboratories. After the results of this study, we can conclude that the carbon material can be used as referencematerial for in-house control of Fe, Ca, Ni, and Si analyses.