Detection of Copper Ion with Laser-Induced Fluorescence in a Capillary Electrophoresis Microchip

Label-free, Water-soluble Fluorescent Peptide Probe for a Sensitive and Selective Determination of Copper Ions

This study aimed to develop a label-free, sensitive, selective, and environment-friendly fluorescent peptide probe His-His-Trp-His (HHWH) for determining the concentration of copper ion (Cu²⁺) in aqueous solutions. The results demonstrated that the designed HHWH has a high selectivity and sensitivity for monitoring the concentration of free Cu²⁺ via quenching of the probe fluorescence upon a binding of Cu²⁺. The fluorescence intensity of the HHWH had a linear relationship with the concentration of Cu²⁺ between 10 nM and 10 μM, and the detection limit was 8 nM. Furthermore, HHWH could be regenerated with sulfide ions at least five times. The concentrations of Cu²⁺ in three different real water samples were detected using this probe, and the results were consistent with the one detected using an atomic absorption spectrometer. Thus, HHWH can be used as an accurate and feasible fluorescent peptide probe for detecting Cu²⁺ in aqueous solutions.

Nano-capillary electrophoresis for environmental analysis

Many analytical techniques have been used to monitor environmental pollutants. But most techniques are not capable to detect pollutants at nanogram levels. Hence, under such conditions, absence of pollutants is often assumed, whereas pollutants are in fact present at low but undetectable concentrations. Detection at low levels may be done by nano-capillary electrophoresis, also named microchip electrophoresis. Here, we review the analysis of pollutants by nano-capillary electrophoresis. We present instrumentations, applications, optimizations and separation mechanisms. We discuss the analysis of metal ions, pesticides, polycyclic aromatic hydrocarbons, explosives, viruses, bacteria and other contaminants. Detectors include ultraviolet-visible, fluorescent, conductivity, atomic absorption spectroscopy, refractive index, atomic fluorescence spectrometry, atomic emission spectroscopy, inductively coupled plasma, inductively coupled plasma-mass spectrometry, mass spectrometry, time-of-flight mass spectrometry and nuclear magnetic resonance. Detection limits ranged from nanogram to picogram levels.