Chemiluminescence-based liquid chromatographic determination of hydrochlorothiazide and captopril

Narrow-bore liquid chromatography has been coupled to chemiluminescence detection for the determination of hydrochlorothiazide and captopril as such and as a two-component mixture in tablet formulations. A narrow-bore C18 reversed-phase column using sodium octane sulphonate as ion-pairing reagent proved suitable for the purpose, Tiopronin was used as the internal standard. Chemiluminescence detection was carried out based on the reaction with Ce(IV) in sulphuric acid medium, sensitized by rhodamine 6G. The response was linearly related to concentration in the range 0.6-200 mu mol l(-1) (R = 0.9992, n = 10) for hydrochlorothiazide and 8-300 mu mol l(-1) (R = 0.9989, n = 10) for captopril. The detection limits (3 sigma blank) are 5 pmol per injection for hydrochlorothiazide and 67 pmol per injection for captopril. The relative standard deviations were 1.8% for 30 mu mol l(-1) hydrochlorothiazide and 4.0% for 66 mu mol l(-1) captopril (n = 11). (C) 1999 Elsevier Science B.V. All rights reserved.