UV-Vis spectrophotometry for the determination of iron and silicon in calcined alumina: evaluation of calibration curves

In laboratories with strict quality requirements, the calibration of equipment is crucial for the reliability of analytical results, especially in the determination of iron and silicon in alumina. This study validated analytical methods by constructing calibration curves for iron (Fe) and silicon (Si) using certified reference materials. The content of iron(III) oxide (Fe2O3) and silicon dioxide (SiO2) in calcined alumina (NIST 699 standard) was evaluated by UV-Vis spectrophotometry. The statistical viability of the calibration models was confirmed with a Student's t-test. The calibration curves for Fe2O3 and SiO2 showed a strong linear relationship (R2 = 0.99891 and R2 = 0.9995, respectively). The analysis of the reference standard yielded concentrations of 0.0129 ± 0.0004% for Fe2O3 and 0.0124 ± 0.0005% for SiO2, demonstrating the accuracy of the method. Statistical analysis confirmed the consistency of the results with the expected theoretical values. In conclusion, the calibration curves showed robustness, the precision was evidenced by the low standard deviation in the replicates, and UV-Vis spectrophotometry proved to be highly reliable and accurate for the quantitative determination of iron and silicon in calcined alumina certified reference material.