Many ordinary cosmetics are now based on mineral nanoparticles and nano-emulsions. Since their first use, benefits of nanotechnology have been widely publicized, but the discussion of the potential effects on their widespread use in consumer are just emerging. Ideally a nanomaterial in cosmetics should be characterized as it appears in the final formulation used by the consumer. Unfortunately, because of the limitations of existing methodologies to achieve this, it seems, that the current best possibility is to characterize the ingredient itself. The need of analytical methods able to detect and monitor the presence of micro- or nano-sized particles inside of commercial products is so a mandatory request, not only to assess the quality of the ingredients but also to establish the safety of the finished products, particularly for the stay-on cosmetic products, which are subjected to a close, direct and prolonged contact with the skin and/or permeable mucous membranes. In this work a whole methodology based on Square Wave Voltammetry (SWV) [1] and ICP-AES, together with the Sedimentation and the Flow Field-Flow Fractionation techniques (SdFFF and FlFFF respectively) [2-3] is proposed to determine the presence of nano- or micro- TiO2 particles in commercial cosmetic formulations, which may have a daily use. The novelties of this study lie in the set-up of an analytical method for the SWV at the hanging mercury drop electrode (HMDE) as alternative identification technique to ICP-AES to quantify the TiO2 content in a complex matrix such as a foundation cream, and the sample type – foundation - which has never taken into consideration before as possible application for the FFF separation techniques, which provide very powerful size-selective sorting methods. The new SWV analytical procedure, based on an acidic digestion microwave-assisted of the sample, was verified by analyzing the P-25 Degussa sample, and the results compared and critically commented with those obtained by the established ICP-AES method. The sizes of the particles contained in the foundations were investigated through SdFFF and FlFFF, sinergically coupled with the ICP-AES, by analyzing aqueous slurries obtained from the foundation through a solvent extraction procedure. The content of the extracted slurries was also checked by TEM observations. 1. Fatouros, N.; Krulic, D.; Larabi, N.; J. Electroanal. Chem., 2005, 579, 243-247. 2. C. Contado, A. Pagnoni, Anal. Chem., 2008, 80(19), 7594-7608. 3. Field-Flow Fractionation Handbook; M. E. Schimpf, K.D. Caldwell, J.C: Giddings, Eds.; Wiley-Interscience: New York, 2000.
TiO2 NANO- AND MICRO-PARTICLES IN COMMERCIAL FOUNDATION: FIELD FLOW FRACTIONATION TECHNIQUES TOGETHER WITH ICP-AES AND SQW VOLTAMMETRY FOR THEIR CHARACTERIZATION
CONTADO, Catia;PAGNONI, Antonella
2010
Abstract
Many ordinary cosmetics are now based on mineral nanoparticles and nano-emulsions. Since their first use, benefits of nanotechnology have been widely publicized, but the discussion of the potential effects on their widespread use in consumer are just emerging. Ideally a nanomaterial in cosmetics should be characterized as it appears in the final formulation used by the consumer. Unfortunately, because of the limitations of existing methodologies to achieve this, it seems, that the current best possibility is to characterize the ingredient itself. The need of analytical methods able to detect and monitor the presence of micro- or nano-sized particles inside of commercial products is so a mandatory request, not only to assess the quality of the ingredients but also to establish the safety of the finished products, particularly for the stay-on cosmetic products, which are subjected to a close, direct and prolonged contact with the skin and/or permeable mucous membranes. In this work a whole methodology based on Square Wave Voltammetry (SWV) [1] and ICP-AES, together with the Sedimentation and the Flow Field-Flow Fractionation techniques (SdFFF and FlFFF respectively) [2-3] is proposed to determine the presence of nano- or micro- TiO2 particles in commercial cosmetic formulations, which may have a daily use. The novelties of this study lie in the set-up of an analytical method for the SWV at the hanging mercury drop electrode (HMDE) as alternative identification technique to ICP-AES to quantify the TiO2 content in a complex matrix such as a foundation cream, and the sample type – foundation - which has never taken into consideration before as possible application for the FFF separation techniques, which provide very powerful size-selective sorting methods. The new SWV analytical procedure, based on an acidic digestion microwave-assisted of the sample, was verified by analyzing the P-25 Degussa sample, and the results compared and critically commented with those obtained by the established ICP-AES method. The sizes of the particles contained in the foundations were investigated through SdFFF and FlFFF, sinergically coupled with the ICP-AES, by analyzing aqueous slurries obtained from the foundation through a solvent extraction procedure. The content of the extracted slurries was also checked by TEM observations. 1. Fatouros, N.; Krulic, D.; Larabi, N.; J. Electroanal. Chem., 2005, 579, 243-247. 2. C. Contado, A. Pagnoni, Anal. Chem., 2008, 80(19), 7594-7608. 3. Field-Flow Fractionation Handbook; M. E. Schimpf, K.D. Caldwell, J.C: Giddings, Eds.; Wiley-Interscience: New York, 2000.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
