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Effect of pH on inhibition and enhancement of luminol‐H 2 O 2 ‐Co 2+ chemiluminescence by phenolic compounds and amino acids
Author(s) -
Cui Hua,
Shi MingJuan,
Meng Rong,
Zhou Jian,
Lai ChunZe,
Lin XiangQin
Publication year - 2004
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2004.tb00390.x
Subject(s) - chemistry , luminol , chemiluminescence , amino acid , deprotonation , medicinal chemistry , phenols , ketone , nuclear chemistry , photochemistry , organic chemistry , biochemistry , ion
The effect of pH on inhibition and enhancement of luminol‐H 2 O 2 ‐CO 2+ chemiluminescence (CL) by 18 phenolic compounds and 20 amino acids was studied. It was found that most of the tested compounds showed an inhibiting effect of lower pH and an enhancing effect at higher pH. At a midrange pH, for some phenolic compounds with two ortho ‐position ‐OH, both an inhibiting and an enhancing peak were simultaneously observed. UV‐visible spectra of the tested phenolic compounds at different pH values were studied. The mechanism for CL inhibition and enhancement was proposed. It is likely that the competition of the ‐OH or the ‐NH 2 group and other reducing groups in the molecules with luminol for O 2 * − led to the CL inhibition. A reaction of ‐COO − and quinone or ketone formed by phenolic compounds at higher pH via deprotonation with O 2 * − also resulted in the CL enhancement.