title: Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.
abstract: Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics.
authors: School of Chemical and Material Engineering, Jiangnan University, Wuxi, P. R. China.
authors: Xiaojin
authors: X
authors: Xu
authors: Xinjiong
authors: X
authors: Ni
authors: Yuhua
authors: Y
authors: Cao
authors: Xiaolu
authors: X
authors: Zhuo
authors: Xiaoxiao
authors: X
authors: Yang
authors: Guangqun
authors: G
authors: Cao
mesh_terms: D000305:Adrenal Cortex Hormones / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D003358:Cosmetics / Q000737:chemistry*; D008823:Micelles; D011109:Polymethacrylic Acids / Q000737:chemistry*
chemical_list: D000305:Adrenal Cortex Hormones; D003358:Cosmetics; D008823:Micelles; D011109:Polymethacrylic Acids; C038300:methylmethacrylate-methacrylic acid copolymer
keywords: Amphiphilic polymeric micelle; Corticosteroids; Cosmetics; Electrokinetic chromatography; Pseudostationary phase