Dysprosium-sensitized chemiluminescence system for the determination of enoxacin in pharmaceutical preparations and biological fluids with flow-injection sampling

A novel trivalence dysprosium(Dy3+)-sensitized chemiluminescence method was developed for the first time for the determination of enoxacin (ENX) using flow-injection sampling based on the chemiluminescence (CL) associated with the reaction of the Dy3+-cerium(Ce(IV))-S2O32--ENX system and the Dy3+-MnO4- S2O32--ENX system. The analytical conditions for CL emission were investigated and optimized. The relationship between the CL intensity of ENX and its concentration has good linearity, with a correlation coefficient of 0.9984-0.9994. The limit of detection (LOD, 3 sigma) was 0.20 ng/mL for the Dy3+-ENX-S2O32--Ce(IV)-H2SO4 system and 0.22 ng/mL for the Dy3+-ENX-S2O32--MnO4--HNO3 system. The relative standard deviation (RSD, n = 11) was 1.8% for 11 determinations of 60 ng/mL ENX. The proposed method was applied to the analysis of ENX in injections, serum and urine samples with a recovery of 98%-105%. A possible mechanism for this sensitized CL reaction is discussed by comparing the CL spectra with the fluorescence emission spectra. The proposed method represents a wide linear range, high sensitivity and accuracy, and can be used for the routine determination of ENX in pharmaceutical preparations and biological fluids. Copyright (C) 2009 John Wiley & Sons, Ltd.