title: Optimization of SERS scattering by Ag-NPs-coated filter paper for quantification of nicotinamide in a cosmetic formulation.
abstract: Supported silver nanoparticles on filter paper were synthesized using Tollens' reagent. Experimental designs were performed to obtain the highest SERS enhancement factor by study of the influence of the parameters: filter paper pretreatment, type of filter paper, reactants concentration, reaction time and temperature. To this end, fractional factorial and central composite designs were used in order to optimize the synthesis for quantification of nicotinamide in the presence of excipients in a commercial sample of cosmetic. The values achieved for the optimal condition were 150 mM of ammonium hydroxide, 50 mM of silver nitrate, 500 mM of glucose, 8 min for the reaction time, 45 °C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1-2 µm). Despite the variation of SERS intensity, it was possible to use an adapted method of internal standard to obtain a calibration curve with good precision. The coefficient of determination of the linear fit was 0.97. The method proposed in this work was capable of quantifying nicotinamide on a commercial cosmetic gel, at low concentration levels, with a relative error of 1.06% compared to the HPLC. SERS spectroscopy presents faster analyses than HPLC, also complex sample preparation and large amount of reactants are not necessary.
authors.affiliation: Department of Chemistry, Federal University of São Carlos, Rodovia Washington Luiz km 235, P.O. Box 676, 13560-970 São Carlos - SP, Brazil. Electronic address: lorizsallum@gmail.com.
authors.forename: Loriz Francisco
authors.initials: LF
authors.lastname: Sallum
authors.forename: Frederico Luis Felipe
authors.initials: FL
authors.lastname: Soares
authors.forename: Jorge Armando
authors.initials: JA
authors.lastname: Ardila
authors.forename: Renato Lajarim
authors.initials: RL
authors.lastname: Carneiro
mesh_terms: D003358:Cosmetics / Q000032:analysis*; D005374:Filtration; D053768:Metal Nanoparticles / Q000737:chemistry*; D009536:Niacinamide / Q000032:analysis*; D010209:Paper; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D003358:Cosmetics; D009536:Niacinamide; D012834:Silver
keywords: Design of experiments; Nicotinamide; Silver nanoparticles; Surface-enhanced Raman spectroscopy