A simple strategy to enhance the sensitivity of fluorescent sensor-based CdS quantum dots by using a surfactant for Hg2+ detection

A simple strategy to enhance the detection sensitivity of fluorescent sensor-based CdS quantum dots (CdS QDs) for the detection of mercury ions (Hg2+) was demonstrated. l-Cysteine-capped CdS QDs (l-Cyst-CdS QDs) were synthesized and utilized as a probe for selective detection of Hg2+. The fluorescence intensity of the l-Cyst-CdS QDs was quenched in the presence of Hg2+. However, the detection sensitivity was unsatisfactory. Upon the addition of sodium dodecyl sulfate (SDS), the fluorescence intensity of l-Cyst-CdS QDs can be effectively enhanced. On the other hand, the fluorescence intensity of the l-Cyst-CdS QDs in the presence of SDS (SDS@l-Cyst-CdS QDs) was able to be dramatically decreased with the addition of Hg2+. Furthermore, the proposed sensor displayed excellent selectivity towards Hg2+ compared to other cations. Under optimized conditions, the proposed sensor could be applied to detect trace amounts of Hg2+ with a limit of detection of approximately 36 nM. The applicability of this sensor was demonstrated by the determination of Hg2+ in real water samples, and the results agreed with those obtained from cold vapor atomic absorption spectrometry (CVAAS).