Theoretical prediction of the chemiluminescence behaviour of the ergot alkaloids. Direct flow injection chemiluminescence determination of ergotamine tartrate

Abstract

The present manuscript is dealing with the application of molecular connectivity calculations to predict the chemiluminescent behaviour of ergot alkaloids when they react with common strong oxidants in liquid phase. Twenty compounds were theoretically studied by means of a discriminant equation formerly published, being 19 of them predicted as chemiluminescent with a high probability. Empirical confirmation of the chemiluminometric behaviour is performed with the few soluble and commercially available ergot alkaloids. On the basis of these results, a new FIA-direct chemiluminescent method is proposed for the determination of the ergot presenting the higher light emission, the pharmaceutical ergotamine. The method is based on the oxidation of the drug by K3[Fe(CN)6] in sodium hydroxide medium, at seventy degrees and enhanced by the presence of dioxane. The studied calibration up to 5.0 mg l−1, revealed a linear dynamic graph up to 0.5 mg l−1. The reproducibility between days resulted in a rsd (in slope %) of 8.9 (n, 5) and the repeatability with a %R.S.D. (n = 20) of 1.9 and 0.6 for 0.3 and 4.0 mg l−1, respectively. LOD (s/n = 3) of 6 × 10−7 mg l−1 and sample throughput of 73 h−1. The influence of foreign compounds is also tested and the optimised flow-assembly is applied to other compounds of the ergot alkaloids family. © 2004 Elsevier B.V. All rights reserved.