RESUMO
Aqueous polymethylmethacrylate (PMMA)-capped CdSe/ZnS quantum dots were used as fluorescence probes for paeonol determination. Based on the fluorescence quenching of aqueous CdSe/ZnS quantum dots caused by paeonol, a simple, sensitive and rapid method was developed. Under the optimal conditions, with excitation and emission wavelengths at 350 nm and 620 nm, respectively, the calibration plot of F0-F with concentration of paeonol was linear in the range of 25.04-175.2 mg L(-1) with correlation coefficient of 0.9986. The limit of detection was 0.017 mg L(-1). The concentration of paeonol in paeonol ointment was determined by the proposed method and the result agreed with the claimed value. Furthermore, the possible fluorescence quenching mechanism was discussed.
Assuntos
Acetofenonas/análise , Compostos de Cádmio/química , Pontos Quânticos , Compostos de Selênio/química , Espectrometria de Fluorescência/métodos , Sulfetos/química , Compostos de Zinco/química , Absorção , Soluções Tampão , Calibragem , Etanol/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Microscopia Eletrônica de Transmissão , Padrões de Referência , Soluções , Temperatura , Fatores de Tempo , Água/químicaRESUMO
Alcohols 8 bearing two identical perfluoroalkyl groups were prepared by the reaction of the corresponding perfluoroalkyl phenyl ketones 7 with 0.5 equivalents of t-BuOK via Cannizzaro-type disproportionation. Utilizing the new bulky bidentate ligand with two n-C(3)F(7) groups generated from 8c, anti-apicophilic phosphorane 5a and its stable isomer 6a were synthesized. The crystal structures of 5a and 6a were slightly affected by the steric repulsion of heptafluoropropyl groups. Kinetic studies on the isomerization of 5a to 6a showed that the new ligand was effective for decreasing the isomerization rate compared with its C(2)F(5) analog 3a to about half.
