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.