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Capillary electrophoresis (CE) and gold nanoparticle aggregation based-colorimetric detection (AuNP/ABCD) were incorporated to provide rapid, sensitive and selective detection of Cd 2+ , Pb 2+ , and Hg 2+ . CE and AuNP/ABCD were interfaced by a pressurized electric field decoupler to isolate the colorimetric reaction solution from the separation voltage. The AuNPs co-functionalized with 11-mercaptoundecanoic acid (MUA) and 6-mercapto-1-hexanol (MCH) were used as colorimetric probes, which provided enhanced sensitivity and good selectivity toward the heavy-metal ions. Under optimal conditions, good linearities were obtained for the analytes, and the detection limits for Cd 2+ , Pb 2+ , and Hg 2+ were 0.214, 0.150, and 0.0214 μg/mL, respectively. The method was successfully applied to cosmetic samples, with recoveries of 87.8% to 103% for the heavy-metal ions spiked. Our results suggested the great potential of the CE-AuNP/ABCD strategy in determining heavy-metal ions in complicated matrices., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A method integrating capillary electrophoresis (CE) and gold nanoparticle aggregation-based colorimetry (AuNP-ABC) was described. By using a dual-sheath interface, the running buffer was isolated from the colorimetric reaction solution so that CE and AuNP-ABC would not interfere with each other. The proof-of-concept was validated by assay of polyamidoamine (PAMAM) dendrimers that were fortified in human urine samples. The factors influencing the CE-AuNP-ABC performances were investigated and optimized. Under the optimal conditions, the dendrimers were separated within 8 min, with detection limits of 0.5, 1.2 and 2.6 μg mL -1 for PAMAM G1.0, G2.0 and G3.0, respectively. The sensitivity of CE-AuNP-ABC was comparable to or even better than those of liquid chromatography-fluorimetry and liquid chromatography-mass spectrometry. The results suggested that the proposed strategy can be applied to facile and quick determination of analytes of similar properties in complex matrices., (Copyright © 2017 Elsevier B.V. All rights reserved.)

[Display omitted] • CDs were greenly synthesized using mango pulps and subsequently treated with ozone. • The ozone-treated CDs could stabilize the diimine form of oxidized TMB. • A dual-detection platform composed of ozone-treated CDs and TMB was developed. • The platform offered sensitive, selective, and reproducible detection of sarcosine. We synthesized excitation-dependent fluorescent carbon dots (CDs) through a one-pot hydrothermal process using mango pulps as precursors and discovered that the ozone-treated CDs (O 3 -CDs) could stabilize the diimine form of oxidized 3,3′,5,5′-tetramethylbenzidine (diimine oxTMB). A dual-mode colorimetry and ratiometric fluorescence method using O 3 -CDs and TMB as probes was developed for detecting sarcosine. During measurement, sarcosine was selectively oxidized by sarcosine oxidase, and the resulting hydrogen peroxide was catalyzed by horseradish peroxidase to convert TMB into a blue-colored oxidized product. Under acidic conditions, this product was further oxidized to diimine oxTMB, which exhibited an absorbance band at 450 nm. Due to the inner filter effect, the fluorescence emission of O 3 -CDs at 450 nm was significantly quenched by the diimine oxTMB, while the emission at 550 nm was utilized as a reference signal. The dual-mode method selectively detected sarcosine, with detection limits of 0.034 µM and 0.096 µM for colorimetry and ratiometric fluorescence detection, respectively. The ratiometric fluorescence sensing strategy provided a built-in correction to prevent errors originating from environmental variabilities. Moreover, the stabilization of diimine oxTMB mediated by O 3 -CDs improved the detection performance of the method. This study enriches the library of luminescent CDs through the rational utilization of natural biomass and introduces a novel approach to improve the analytical performance of dual-mode detection. [ABSTRACT FROM AUTHOR]