A novel on-line gold nanoparticle-catalyzed luminol chemiluminescence detector for high-performance liquid chromatography

Abstract

A novel on-line gold nanoparticle-catalyzed luminol–H2O2 chemiluminescence (CL) detector for high-performance liquid chromatography (HPLC) was established, in which gold nanoparticles were produced by the on-line reaction of H2O2, NaHCO3–Na2CO3 (buffer solution of luminol), and HAuCl4. Eight phenolic compounds (gallic acid, protocatechuic acid, protocatechuic aldehyde, 2,5-dihydroxybenzoic acid, caffeic acid, 2,3-dihydroxybenzoic acid, (+)-catechin, and (−)-epicatechin) were chosen as the model compounds. Every separated phenolic compound in the column eluent strongly enhanced the CL signal of on-line gold nanoparticle-catalyzed luminol system. The CL and UV–visible absorption spectra and transmission electron microscopy studies were carried out, and the CL enhancement mechanism was ascribed to that the presence of phenolic compound promoted the on-line formation of 38-nm-diameter gold nanoparticles, which better catalyzed the luminol–H2O2 CL reaction. The effects of methanol and phosphoric acid in the proposed HPLC configuration were performed by two gradient elution programs, and the baseline profile revealed that on-line gold nanoparticle-catalyzed luminol–H2O2 CL detector had better compatibility than 38nm gold colloids–luminol–H2O2 CL detector. The proposed CL detector exhibits excellent analytical performance with the low detection limit (S/N=3) of 0.53–0.97ng/mL (10.6–19.4pg) phenolic compounds, and offers a new strategy for developing on-line nanoparticle-catalyzed CL detector for HPLC with sensitive analysis.