title: Validation of an isocratic LC method for determination of quercetin and methylquercetin in topical nanoemulsions.
abstract: The aim of this study was to validate an isocratic LC method for the quantification of either quercetin (Q) or methylquercetin (MQ) incorporated in topical nanoemulsions. The analyses were performed at room temperature on a reversed-phase C(18) column using a mobile phase composed of methanol/water (70:30, v/v) and trifluoracetic acid 0.1% at 0.8 mL min(-1). The detection was carried out on a UV detector at 368 or 354 nm for Q and MQ, respectively. The linearity, in the range of 0.15-1.5 microg/mL, presented a determination coefficient (r(2)) higher than 0.99, calculated by the least square method for both flavonoids. No interferences from the excipients (egg-lecithin or octyldodecanol) were detected. The R.S.D. values for intra- and inter-day precision experiments were lower than 2% for both flavonoids. The recovery ranged from 98.9% to 103.46% for Q and from 98.9% to 102.92% for MQ.
authors.affiliation: Universidade Federal do Rio Grande do Sul, Faculdade de Farmácia, Programa de Pós-Graduação em Ciências Farmacêuticas, Porto Alegre, RS, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fasolo
authors.forename: Liege
authors.initials: L
authors.lastname: Schwingel
authors.forename: Maribete
authors.initials: M
authors.lastname: Holzschuh
authors.forename: Valquíria
authors.initials: V
authors.lastname: Bassani
authors.forename: Helder
authors.initials: H
authors.lastname: Teixeira
mesh_terms: D000287:Administration, Topical; D002853:Chromatography, Liquid / Q000379:methods*; D004655:Emulsions; D036103:Nanotechnology / Q000379:methods*; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry; D011794:Quercetin / Q000031:analogs & derivatives* / Q000032:analysis*; D015203:Reproducibility of Results
chemical_list: D004655:Emulsions; D004364:Pharmaceutical Preparations; D011794:Quercetin