Integrating HPLC Fingerprinting, Gray Relational Analysis, and In Vitro–In Vivo Evaluation of Xiaochaihu Decoction and Its Nano‐Phase

N-XCH, as a self-assembled nanoemulsion phase in XCH decoction, markedly improves the systemic exposure and liver targeting of representative actives without excessive peak concentrations. These findings highlight the potential of SANS in TCM decoctions to optimize oral bioavailability and organ targeting, and provide an integrated analytical-pharmacokinetic framework for linking spectrum-effect relationships with nano-phase behavior.