Fast and Simple Spectrophotometric Procedure for Determination of TiO2 in Paint Samples

Author(s)

Reis, Felipe Eduardo ; Maringolo, Vivian ; Rocha, Diogo Librandi

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF ANALYTICAL CHEMISTRY; v. 6, n. 22, p. 8-pg., 2019-01-01.

Abstract

Paints are commonly used to protect solid surfaces and to cover imperfections. The composition alters the characteristics of the paint such as brightness, and resistance to abrasion. An important component of paints is TiO2, which yields a strong white color and opacity. Due to the cost of this raw material, its employment is limited. The determination of TiO2 is important for quality control and for developing formulations with lower content of TiO2. Additionally, deformulation studies are generally carried out aiming at aiding market assessment. The reference procedure for determination of TiO2 is based on a volumetric method using highly unstable species such as Ti(III) and Fe(II), making it extremely susceptible to systematic errors. Alternative procedures with atomic absorption or emission techniques are expensive for research laboratories in the industry, especially when the determination of a few metals is required. In this sense, a simple spectrophotometric procedure for TiO2 determination in paint samples is herein proposed, based on the reaction between Ti(IV) and H2O2 that yield a soluble complex with absorption maximum at 435 nm. The univariate optimization of the parameters was carried out aiming at best sensitivity and analytical frequency, and minimum reagent consumption and waste generation. Linear response was observed between 6.0 and 60 mg L-1 Ti. Detection limit (n = 20, 99.7% confidence level) and coefficient of variation (n = 20) were estimated at 2.8 mg L-1 and 1.2 %), respectively. Sample preparation was based on ashing, and dissolution in hot mixture of sulfuric and hydrochloric acids. The analysis of the digests by the proposed and the titrimetric reference procedures agreed at the 95% confidence level. The developed procedure is a faster, low-cost, reliable and cleaner alternative for determination of TiO2 in paint samples. (AU)

• FAPESP's process: 15/12172-6 - Flow-based analytical procedures exploiting on-line decompositions and extractions for fractionation and total determinations
• Grantee: Diogo Librandi da Rocha
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/05559-0 - Evaluation of microdecomposition and microextraction strategies for quality control of fuels
• Grantee: Diogo Librandi da Rocha
• Support Opportunities: Regular Research Grants