A selective determination of copper ions in water samples based on the fluorescence quenching of thiol‐capped CdTe quantum dots

Abstract

CdTe quantum dots (QDs) capped with different stabilizers, i.e. thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA) and glutathione (GSH) were investigated as fluorescent probes for the determination of Cu(2+). The stabilizer was shown to play an important role in both the sensitivity and selectivity for the determination of Cu(2+). TGA-capped CdTe QDs showed the highest sensitivity, followed by the MPA and GSH-capped CdTe QDs, respectively. The TGA- and MPA-capped CdTe QDs were not selective for Cu(2+) that was affected by Ag(+). The GSH-capped CdTe QDs were insensitive to Ag(+) and were used to determine Cu(2+) in water samples. Under optimal conditions, quenching of the fluorescence intensity (F0/F) increased linearly with the concentration of Cu(2+) over a range of 0.10-4.0 µg/mL and the detection limit was 0.06 µg/mL. The developed method was successfully applied to the determination of Cu(2+) in water samples. Good recoveries of 93-104%, with a relative standard deviation of< 6% demonstrated that the developed simple method was accurate and reliable. The quenching mechanisms were also described.

Branched Ligand Ethyl 2‐Mercaptopropionate as a Stabilizer for CdTe Quantum Dots and its use as a Cu2+ Ions Probe in Aqueous Medium

“…No significant interference could be observed from the investigated metal ions. Interestingly, Ag + was not observed as an interferent as reported elsewhere, using TGA and MPA as ligands . Therefore, the present sensor acts as a potential candidate for the sensing of Cu 2+ without the need for separation of interferents.…”

“…A comprehensive study on the performance of CdTe@E2MP sensor among other CdTe QDs based sensors is performed and the results are tabulated in Table 1. The CdTe@E2MP sensor is comparable with other CdTe QDs based sensors capped with different capping ligands like TGA, MPA, GSH etc.. [7,27,[45][46][47][48][49][50][51]…”

Determination of Cu2+ in Drinking Water Based on Electrochemiluminescence of Ru(phen)32+ and Cyclam

“…Although these techniques can be utilized to detect Cu 2+ , they are complicated, utilizing expensive instruments and requiring a time‐consuming sample pre‐treatment. To overcome these problems, fluorescence spectroscopy has attracted interest as the high‐performance alternative method for the fast determination of Cu 2+ because of several advantages, such as high sensitivity, specificity and ease of operation. Several fluoroionophores have been developed for Cu 2+ by utilising the excellent molecular recognition ability of cyclam (Scheme ) in ‘fluorophore‐spacer‐receptor’ mode .…”

“…To overcome these problems, fluorescence spectroscopy has attracted interest as the high‐performance alternative method for the fast determination of Cu 2+ because of several advantages, such as high sensitivity, specificity and ease of operation. Several fluoroionophores have been developed for Cu 2+ by utilising the excellent molecular recognition ability of cyclam (Scheme ) in ‘fluorophore‐spacer‐receptor’ mode . However, these fluorescent methods are also limited by complex organic synthesis, harmful organic co‐solvent system, autofluorescence background, excitation power fluctuation, photobleaching, etc.…”

CdTe/ZnS quantum dots as fluorescent probes for ammonium determination

“…Researchers have found that water-soluble QDs could be used as selective inorganic ion probes to determining CN À , H + , Ag + , Hg 2+ , Cu 2+ , Fe 2+ , Ni 2+ , Pb 2+ , Mn 2+ , Zn 2+ , and Co 2+ (22)(23)(24)(25)(26)(27). Interestingly, cationic dyes and surfactants can quench QDs extensively (28,29).…”