Comparative evaluation of conventional acid digestion and a calcination-assisted sample preparation for titanium dioxide determination in paints by UV-vis spectrophotometry.

Titanium dioxide (TiO2) is a critical functional component in paint formulations, providing essential properties such as opacity, whiteness, UV resistance, high cleaning power and durability. Given that TiO2 is among the most expensive raw materials in the industry, accurate quantification is vital for both quality control and cost-benefit optimization. This study aimed to optimize a routine analytical method for TiO2 determination by focusing on the sample preparation stage-the most resource-intensive phase of the process. A comparative analysis was conducted between the traditional direct acid digestion method and a proposed alternative incorporating a calcination step. The performance was evaluated using UV-vis molecular spectroscopy based on validation criteria including analysis time, reagent consumption, and sample throughput. The optimized method demonstrated high linearity (R2 > 0.99) with a Limit of Detection (LOD) and Limit of Quantification (LOQ) of 4.35 and 5.76 mg L-1, respectively. The process proved precise and accurate, with a Coefficient of Variation (CV) below 5.0% and recoveries exceeding 95% across all concentration levels. While statistical differences between analysts were noted for two solvent-based samples (t-test > t-critical of 12.7), the calcination step demonstrated significant advantages for routine operations. Implementation resulted in a 50% reduction in total analysis time, a 25% decrease in acid consumption, and a 75% reduction in energy expenditure. Furthermore, evaluation via the AGREEprep tool confirmed that the proposed method significantly enhances analyst safety and aligns with green analytical chemistry principles.