Analysis of Transdermal Distribution and Blood Components in Guinea Pigs Following the Application of Bai Jie Zi San Using Matrix‐Assisted Laser Desorption Ionization Mass Spectrometry Imaging and Ultra‐High‐Performance Liquid Chromatography‐Quadrupole‐Time‐of‐Flight Mass Spectrometry

ABSTRACT Introduction Bai Jie Zi San (BJZS) is a traditional Chinese herbal formula commonly used in acupoint sticking therapy, extensively used in clinical practice for the prevention and treatment of asthma. It has a wide application not only in China but also across various East Asian countries. Objective This study aimed to analyze the transdermal distribution and blood components in guinea pigs following the application of BJZS. Methods We used matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) to visualize the transdermal spatial distribution of BJZS components in the skin tissue of guinea pigs and ultra‐high‐performance liquid chromatography‐quadrupole‐time‐of‐flight mass spectrometry (UHPLC‐Q‐TOF‐MS) to identify the components present in the blood. Results The results revealed significant differences in the distribution of each component across various skin areas of the guinea pigs, with the Feishu acupoint showing significantly higher concentrations compared to the other acupoints. Seventeen components were successfully identified in the blood, including eight from Corydalis Rhizoma, four from Asari Radix et Rhizoma, two from Semen Sinapis Albae, two from Rhizoma zingiberis recens, and one from Kansui Radix. Conclusion The study demonstrated that combining MALDI‐MSI with UHPLC‐Q‐TOF‐MS technology offered an intuitive, straightforward, and reliable approach to effectively reflect the distribution characteristics of transdermal components and identify the types of components entering the bloodstream after the application of BJZS. These findings provided valuable insights into the pharmacological mechanisms and modern development of this traditional Chinese herbal formula.