Sensitive and selective capillary electrophoretic analysis of proteins by zirconia nanoparticle-enhanced copper (II)-catalyzed luminol–hydrogen peroxide chemiluminescence

We report herein a sensitive, selective, convenient CE determination of heme proteins in complex matrices by a sodium-dodecyl-sulfate-assisted, zirconia nanoparticle-enhanced copper (II)-catalyzed luminol–hydrogen peroxide chemiluminescence (CCLHPCL). Introducing a segment of sodium dodecyl sulfate to the capillary after sample injection not only rendered selective detection by quenching the luminescence signals from the non-heme proteins but also owning to the suppressed protein adsorption, led to significant improvement in separation efficiency and detection sensitivity. The signals were further improved by addition of ZrO2 nanoparticles to the chemiluminescence solution. Compared with the conventional CCLHPCL, the detection limits (S/N=3) were improved by 10.2–22.0 folds, with 7.8×10−9, 3.3×10−9 and 1.5×10−9 M for three model proteins, viz, myoglobin, hemoglobin and cytochrome C, respectively. Because the method did not require sophisticated pretreatment, it was convenient to analyze heme proteins in complex matrices, as demonstrated, hemoglobin in human blood and spiked human urine samples.