The inhibition and enhancement of liquid phase CL by organic compounds are of considerable(interests) in analytical chemistry because they can be used for the sensitive detection of numerous compounds.However

the mechanism of inhibition and enhancement is not fully understood and the discovery of new(enhancers) and inhibitors is usually achieved in an empirical fashion by trail and error.Although there are(reports) in the literatures concerning the use of the luminol-KIO

4

-H

2

O

2

CL for the determination of hydrogen peroxide

glucose and ascorbic acid

the effect of aromatic compounds on the luminol-KIO

4

-H

2

O

2

CL has not been studied systematically.The effects of 36 organic compounds on the luminol-KIO

4

-H

2

O

2

system chemiluminescence(CL) were studied under different pH conditions of luminol solution.The CL signal was detected with a flow injection chemiluminescence system(Xi'an Ruimai Electronic Technology Co.

Ltd.

China) consisted of a model IFFM-D peristaltic pump

a mixing tee

a model IFFS-A CL detector equipped with a glass coil(used as reaction coil and detection cell)

a photomultiplier

and IBM compatible microcomputer.It was found that most of the tested compounds could inhibit or enhance the CL intensity.The activities of such(inhibitors) or enhancers were related to pH value of the CL system and the number and position of functional groups such as —OH and —NH

2

on aromatic ring and property of substituent group

electron delocalization and steric hindrance.The CL spectra and UV-visible absorption spectra were studied and the mechanism for the CL inhibition and enhancement was also discussed.The mechanism for such inhibition or enhancement of organic compounds is most likely due to the reactions between inhibitors or enhancers and radical intermediates of the CL reactions.Based on the CL inhibition or enhancement

the possibility of analytical applications was explored.The results demonstrated that numerous compounds are detectable at ng·mL

-1

level.