Journal of Chromatography B, 833 (2006) 260–263 Short communication Determination of four water-soluble compounds in Salvia miltiorrhiza Bunge by high-performance liquid chromatography with a coulometric electrode array system Lijuan Ma a,1 , Xuezhu Zhang b,1 , Hui Guo b , Yiru Gan a,∗ a Department of Biochemical Engineering School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China b The First Hospital affiliated to Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China Received 24 November 2005; accepted 18 January 2006 Available online 24 February 2006 Abstract A method has been developed to determine the four water-soluble components—Danshensu (I), protocatechuic acid (II), protocatechuic aldehyde (III) and salvianolic acid B (IV) in Chinese medicine plant Salvia miltiorrhiza Bunge using high-performance liquid chromatography with a coulometric electrode array detection (HPLC–CEAD) system. Heat reflux extraction was used to pretreat the sample. This analysis was carried on a column of Hypersil C 18 (250 mm × 4.6 mm, 5 m) with a mobile phase of sodium acetate (pH 2.5, 50 mM) and acetonitrile in gradient mode. An ESA electrochemical detector monitored the four compounds. Potentials of four electrodes in series were set at 100, 150, 200 and 250mV, respectively. Optimization of the pH of mobile phase and the proportion of acetonitrile were also performed. Calibration curve showed good linearity with correlation coefficients (r) more than 0.9937. Average recoveries of the four compounds were more than 92% and relative standard deviations were less than 6.6%. This method appeared to be stable, sensitive and reproducible for determination of the four water-soluble compounds in Chinese medicine plant S. miltiorrhiza Bunge. © 2006 Elsevier B.V. All rights reserved. Keywords: HPLC; Electrochemical detector; Chinese medicine plant; Salvia miltiorrhiza Bunge 1. Introduction The root and rhizome of Salvia miltiorrhiza Bunge (Labi- atae), Danshen in Chinese, has been commonly used in Chi- nese traditional medicine (CTM) in the treatment of coronary artery disease and cerebrovascular diseases including stroke [1]. The effective components of the roots could be classified as lipid-soluble and water-soluble. In recent years, the lipid- soluble components and their pharmacological functions have been largely researched. However, decoction with water is the conventional method of taking CTM. Danshensu (I), protocate- chuic acid (II), protocatechuic aldehyde (III) and salvianolic acid B (IV) have been isolated and identified as the main constitutes in water-soluble compounds [2]. Pharmacological experiments ∗ Corresponding author. Tel.: +86 22 27409598; fax: +86 22 27409598. E-mail address: ganyiru@yahoo.com.cn (Y. Gan). 1 These authors contributed equally to this work and can also be seen as the first author. have demonstrated that IV can effectively restrain lipid peroxida- tion of the brain, liver and kidney; I can protect cardiac muscle from lacking blood and oxygen; III can increase the flux of coronary [3]. Therefore, it is of great practical significance to establish an analytical method for determining them. To detect water-soluble components in S. miltiorrhiza Bunge, colorimetric method [4], ultraviolet spectrophotometric method [5], high-performance capillary electrophoresis (HPCE) [6], thin layer chromatography (TLC) [7] and high-performance liquid chromatography (HPLC) [8–15] have been reported. Never- theless, the first two methods are usually interfered by other compounds; the results of TLC have a bad repeatability and accu- racy while the sensitivity of HPCE is restricted by low sample injection and short optical length. Among them, HPLC is most widely used. The coulometric electrode array detection (CEAD) would be an ideal choice to separate the overlap peaks of the co-eluting analytes because of electroactive phenolic hydroxyl group in these four aqueous soluble compounds (Fig. 1) [16]. CEAD consists of 4–16 electrochemical cells arranged in series and the 1570-0232/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jchromb.2006.01.021