Determinação de Cério em matrizes semi-sólidas: investigação de estratégias de preparo de amostra e aplicação de métodos instrumentais

Abstract

The present work aimed at the development and validation of analytical methodologies for the determination of cerium in topical medications containing cerium nitrate, in cream and gel formulations. The study involved the investigation of sample preparation strategies, with emphasis on liquid-liquid extraction (LLE) and microwave-assisted acid digestion. Analytical determinations were performed by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). The methods were validated according to the criteria of ANVISA Resolution RDC 166/2017, evaluating parameters such as selectivity, linearity, precision, accuracy, detection limits, and robustness. The results demonstrated that microwave-assisted acid digestion presented better performance for both matrices, allowing accurate and precise quantification of Ce in cream and gel pharmaceutical formulations. Method validation by ICP-OES demonstrated satisfactory performance, with adequate selectivity (recoveries between 97.6–100.8 %), excellent linearity (r = 1.00, homoscedastic residuals), consistent accuracy (96.9–102.2 %), high precision (RSD ≤ 2.0%), and acceptable robustness. For ICP-MS, the parameters also met the criteria: selectivity within 95.0–105.0 %, adequate linearity (r = 0.995; r² = 0.989, homoscedastic residuals), satisfactory accuracy (96.0–102.5 %), adequate precision (RSD < 4.0%), and confirmed robustness against operational variations. The data obtained confirm the applicability of the proposed methodologies for the quality control of cerium-containing pharmaceutical products, demonstrating their suitability not only for routine quantification of the active ingredient but also for monitoring its content in stability studies, in compliance with current regulatory requirements.