title: Application of nanofiber-packed SPE for determination of salivary-free cortisol using fluorescence precolumn derivatization and HPLC detection.
abstract: Salivary cortisol has emerged as an easy-to-collect biologic marker of stress in many researches. In this study, we present a method for the determination of salivary-free cortisol using HPLC method with fluorescence precolumn derivatization, which is based on a novel extraction from the strongly acidic medium (fluorescent derivatives of cortisol in sulfuric acid medium) by electrospun polystyrene nanofibers packed SPE. For high-throughput sample extraction, an array pretreatment device based on nanofibers packed SPE micro-column was designed. The LOD of cortisol was 0.01 microg/L (S/N=3). The RSDs (n=6) for all analytes were below 8.0%, and the recoveries were 110, 102.4, and 99.4% (n=3) for saliva spiked with 0.1, 10, and 20 microg/L of cortisol, respectively. The proposed method was then successfully applied in the determination of free cortisol in human saliva. The salivary cortisol concentrations in the real samples ranged from 0.22 to 7.45 microg/L. The nanofiber-packed SPE overcame the low extraction recovery and bad clean-up effect of the conventional methods, and increased the sensitivity and selectivity of the method.
authors.affiliation: Key Laboratory of Child Development and Learning Science (Ministry of Education), Research Center for Learning Science, Southeast University, Nanjing, P. R. China.
authors.forename: Li-Qin
authors.initials: LQ
authors.lastname: Chen
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Kang
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Deng
authors.forename: Zhong-Ze
authors.initials: ZZ
authors.lastname: Gu
authors.forename: Zu-Hong
authors.initials: ZH
authors.lastname: Lu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005453:Fluorescence; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D057139:Nanofibers / Q000737:chemistry*; D012463:Saliva / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*
chemical_list: D006854:Hydrocortisone