土荊皮為常用中藥材，來源於松科植物金錢松Pseudolarix kaempferiGord.的乾燥根皮，常用於治療真菌感染引起的皮膚疾病等。本文首次建立了同時測定土荊皮中土荊甲酸、土荊乙酸和土荊丙酸3個主要二萜酸類成分含量的方法，並對收集到的8份藥材進行了分析。採用Zorbax XDB RP-C18（4.6 mm × 250 mm, 5 μm）管柱，以乙捷-1%冰醋酸溶液為流動相梯度沖提（0→30 min：30%→60%乙捷），流速為1.0 mL/min，檢測波長為260 nm。在此層析條件下，3個成分得到良好的分離效果，土荊甲酸、土荊乙酸和土荊丙酸分別在0.982-98.2 μg/mL，0.618-61.8 μg/mL，1.052-105.2 μg/mL呈良好的線性關係，相關係數均大於0.999。所測6份正品土荊皮藥材中，土荊甲酸、土荊乙酸和土荊丙酸的含量範圍分別為0.097-0.153%，0.266-0.406%和0.037-0.098%。2份混淆品藥材水翁皮中未檢測到這3個成分。本方法簡便易行、準確可靠，可同時測定土荊皮中3個主要的二萜酸類成分的含量，較全面地對土荊皮藥材進行質量控制。

The root bark of Pseudolarix kaempferi, a famous traditional Chinese medicine, has been commonly used in China to treat skin diseases caused by fungal infections. To evaluate its pharmatherapeutic quality, a sensitive, simple and accurate high-performance liquid chromatography (HPLC) method was developed for the quantitative analysis of three major bioactive diterpenoids, pseudolaric acids A-C in P. kaempferi. A Zorbax XDB RP-C18 (4.6 mm × 250 mm, 5 μm) was used in this HPLC system, with UV detection at 260 nm. A gradient elution was effected by a mobile phase composed of acetonitrile and 1% aqueous acetic acid, where acetonitrile concentration was changed from 30% to 60% in 30 min. These three constituents were well resolved by this method with good linear relationships in the range of 0.982-98.2 μg/mL for pseudolaric acid A, 0.618-61.8 μg/mL for pseudolaric acid B, and 1.052-105.2 μg/mL for pseudolaric acid C, respectively. The correlation coefficients of the calibration curves were all over 0.999. In addition, these three compounds in six batches of the root barks of P. kaempferi were quantitatively determined to evaluate the effectiveness of this method.