LC and LC-MS-MS analyses of undeclared codeine in antiasthmatic Chinese proprietary medicine

This paper describes an accurate and sensitive reversed phase high-performa nce liquid chromatographic (RP-HPLC) method for the detection and quantific ation of undeclared codeine in a Chinese Proprietary Medicine (CPM) for ast hma. A rapid and specific liquid chromatography-mass spectrometry-mass spec trometry (LC-MS-MS) method was applied to confirm the presence of codeine b y selected reaction monitoring (SRM). Codeine was extracted from the capsul es by dissolving in sodium dihydrogen phosphate buffer (10 mM, pH = 2.2) an d ethanol, then made alkaline (pH = 9) and extracted using chloroform. The amount of codeine in AsthmaWan was found to be 61.8 mu g/capsule (R.S.D. = 7.9%, n = 9). Excellent resolution was obtained despite the complexity of t he product which claimed to contain at least nine herbal ingredients, none of which will give rise to codeine. As a further confirmation method, LC-MS -MS is accurate and specific. The LC method has been validated for linearit y, limit of detection, limit of quantification, accuracy and specificity. G reater awareness of and control over undeclared drugs in complementary medi cine are necessary to ensure patients' safety. (C) 2000 Elsevier Science B. V. All rights reserved.