科研之友
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摘要
In this study, a liquid-phase solvent bar micro-extraction technique was used to investigate both the extraction and back-extraction processes of the target analyte. A novel concentration curve method and a classic time curve method, used under the same experimental conditions, verified the symmetry between the extraction process (target analyte moves from sample matrix to the organic solvent-based extraction phase) and the back-extraction process (target analyte moves from organic solvent to the sample matrix), providing the basis to use the target analyte in the back-extraction process to calibrate its extraction process. A quantitative calibration can be achieved using back extraction on the target analyte from the blank sample matrix in the organic solvent. Information from the process of back extraction of the target analyte, such as the time constant a, can be directly used to calculate the initial concentration of the target analyte in the sample matrix. This new kinetic calibration method employs a liquid-phase solvent bar micro-extraction technique combined with high-performance liquid chromatography with a diode array detector (HPLC-DAD) and was successfully used to analyze three local anesthetics in biological samples; it extends the application of the kinetic calibration to HPLC-DAD and establishes a novel, simple and accurate method to determine the concentration of the free drug in biological samples and its protein-binding ratio.
