Abstract: In this paper, it was found that the isoniazide could be effectively preconcentrated onto the carbon paste electrodes doped with bentonite.Then, based on the medium exchange and its sensitizing effect of isoniazide for the weak ECLsignal of electrooxidation luminol, the isoniazide could be sensitively and selectively detected witHECLmethod.In addition, it was also found that the blank ECLsignal of electrooxidation luminoLItself, compared to the unmodified CPE, was effectively decreased on the surface of bentonite modified CPE.In this case, a more higher ratio of the ECLsignal to the noise for detecting isoniazide with this chemically modified CPEwas obtained.Based on these findings, a more sensitive and selective ECLmethod for the determination of isoniazide was developed.At the same time, a new concept, to improve the sensitivity of luminol ECLsystem, based on using chemically modified CPE, was also first developed in this paper.Under the selecting experimental conditions, the relative ECLintensity was linear with isoniazide concentration in the range of 5.0×10^-9-8.0×10^-7mol/L.The correlation coefficient is 0.9984.

Key words: Electrochemiluminescence analysis, Luminol, Isoniazide determination, Bentonite chemically modified carbon paste electrode