title: Calibration of pre-equilibrium HF-LPME and its application to the rapid determination of free analytes in biological fluids.
abstract: This study establishes a novel calibration method for pre-equilibrium hollow-fiber liquid-phase microextraction (PE-HF-LPME), where the time constant of the extraction of the analyte from sample matrix to the extraction phase (organic solvent) is obtained from a simple concentration curve. Comparing to the traditional kinetic calibration method, where the time constant was obtained from the extraction time profile, the new calibration approach shows improved accuracy and precision. More importantly, deuterated standards are not required in the new method, thus significantly improving its cost-effectiveness and extending its applicability to a wide range of analytes lack of deuterated analogs serving as internal standards. In addition, mass spectrometry is not necessary for the quantification of analytes with the new calibration method, which may further extend the applicability of PE-HF-LPME to some laboratories without mass spectrometers. This study has been substantiated with both theoretical and experimental evidences. Further, the feasibility of the method for real biological samples was demonstrated by measuring the free concentration of flunitrazepam in urine and plasma samples and its drug-protein binding ratio in plasma. The results showed that the method had a short analysis time and was easily implemented with high accuracy and good reproducibility.
authors.affiliation: Department of Biological Applied Engineering, Shenzhen Key Laboratory of Fermentation, Purification and Analysis, Shenzhen Polytechnic, Shenzhen 518055, China.
authors.forename: Baiqiu
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Biological Applied Engineering, Shenzhen Key Laboratory of Fermentation, Purification and Analysis, Shenzhen Polytechnic, Shenzhen 518055, China; School of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 510275, China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Biological Applied Engineering, Shenzhen Key Laboratory of Fermentation, Purification and Analysis, Shenzhen Polytechnic, Shenzhen 518055, China.
authors.forename: Jinxing
authors.initials: J
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Verschuren Centre for Sustainability in Energy and the Environment, Cape Breton University, Sydney B1P 6L2, Canada.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Biological Applied Engineering, Shenzhen Key Laboratory of Fermentation, Purification and Analysis, Shenzhen Polytechnic, Shenzhen 518055, China. Electronic address: shufencui@163.com.
authors.forename: Shufen
authors.initials: S
authors.lastname: Cui
mesh_terms: D001826:Body Fluids / Q000737:chemistry; D002138:Calibration; D005445:Flunitrazepam / Q000097:blood / Q000652:urine; D059627:Liquid Phase Microextraction / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D005445:Flunitrazepam
keywords: Calibration; Concentration curve method; Fast analysis; Free concentration; Hollow fiber liquid-phase microextraction (HF-LPME); Time constant α