Abstract
A fast and simple method for the extraction and Flame Atomic Absorption Spectroscopy (FAAS) quantification of ZnO in different cosmetic matrices, including lipsticks, water-in-oil foundations, and oil-in-water creams, was developed and validated, according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) and the United States Pharmacopeial Convention guidelines. The sample preparation consisted of an ultrasound-assisted ethanolic extraction of ZnO followed by digestion with 1 M nitric acid (HNO3). Samples were analyzed by Flame Atomic Absorption Spectroscopy (FAAS). Specificity, linearity, the limit of detection (LOD), the limit of quantification (LOQ), sensitivity, precision, and accuracy parameters were studied. The robustness of the method was evaluated with a five-variable Youden–Steiner model. The method was specific for ZnO, and the extraction procedure did not affect the stability of the signal compared to the background. The method was linear in the range 0.2–1.0 mg/L with LOD/LOQ values equal to 0.0156 (mg·L−1)/0.0473 (mg·L−1), 0.0098 (mg·L−1)/0.0297 (mg·L−1), 0.0113 (mg·L−1)/0.0341 (mg·L−1), and 0.0131 (mg·L−1)/0.0397 (mg·L−1), respectively, for raw material, lipstick, liquid foundation, and emulsion matrices. Regarding precision, the %RSD values were below 3.0% for repeatability and intermediate precision. Global reproducibility RSD was below 8.0% for all matrices. The percentage of recovery was not statistically different from 100% in all cases. The final concentration was found to be a critical variable for all matrices except for the raw material. The variables associated with the extraction step (ethanol volume, bath temperature, and extraction time) were critical in the extraction of liquid foundations and cream emulsions. The method reduces the number and concentration of mineral acids spent on the digestion of ZnO, and its application is extendable to raw materials. This development is an adequate tool for routine analysis and cosmetic quality control of chemically different products that contain ZnO as ultraviolet radiation (UV) filter, to guarantee regulatory compliance and ensure the safety and efficacy of products delivered to consumers.
Highlights
Cosmetics have played an important role in our society since ancient times until today, driven in part by a constantly evolving innovation culture [1, 2]
We aim to develop and validate a simplified method for the routine extraction and quantification of zinc oxide (ZnO) in different cosmetic matrices by Flame Atomic Absorption Spectroscopy (FAAS), assessing its specificity, linearity, precision, accuracy, and robustness according to ICH and United States Pharmacopeia guidelines [33, 34]
Development. e cosmetic matrices considered in this work include lipsticks, which can be thought of as waxy matrices [36], to foundations, including but not limited to water-in-oil emulsions which contain dimethicone and dimethicone-derived emulsifiers [37, 38], and cream emulsions that include both water-in-oil and oil-inwater emulsions [4]. e diverse chemical properties of these matrices make the use of an extraction solvent necessary, as direct acid digestion might require long times for products with high lipophilic material content
Summary
Cosmetics have played an important role in our society since ancient times until today, driven in part by a constantly evolving innovation culture [1, 2]. Skincare accounts for 40% of the total market size, well ahead of haircare (21%) and makeup (18%) segments [3]. Nowadays, innovation in those segments is concerned with the development of multifunctional products with appealing properties [4]. No addition of zinc standard was performed on raw material samples, as the concentration reported in its certificate of analysis was assumed as the nominal value. Method standard conditions and alternative conditions were studied in eight experiments for each cosmetic matrix and the raw material. Critical variables were tho√se that exhibited an absolute difference greater than σ ∗ 2, where σ is the standard deviation derived from the repeatability assays
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
