Abstract
“Turn-off” fluorescent sensors for Cr(VI) have been fabricated based on organic polymer-capped gold nanoparticles. The fluorescence intensity, as well as the response behavior of the sensors, is dependent on the pH values of buffer solution and dilution amounts of the sensors. When diluted 50 times with pH 2.0 buffer solution, the sensors show good linear responses toward Cr(VI) at concentrations between 2.8–5.9 μM and 5.9–29 μM. The calculated detection limit is 0.63 μM (S/N=3). The interference study and real sample assays exhibit satisfying selectivity and reliability results. Furthermore, the quenched intensity of fluorescence could be recovered by Fe(II) ion, which provides a potential method to detect Fe(II) ions. The quenching and recovering mechanisms have also been investigated. It is suggested that the quenching mechanism is based on the combined effects of internal electron transfer and the inner filter effect. Finally, the recovering mechanism is based on the redox reactions between the Cr(VI) and Fe(II) ions.
Highlights
Chromium is commonly used in industrial applications, such as producing many commercially important alloys and tanning agents
certified reference material (CRM) was spiked in water samples, which were measured by atomic absorption spectroscopy (AAS) for comparisons
It is well-known that chromium exhibits different types of pH
Summary
Chromium is commonly used in industrial applications, such as producing many commercially important alloys and tanning agents. Several reports have unraveled that the amino groups of PEI and aldehydes (or ketones) can react to produce fluorescent polymers [20, 21], of which the fluorescence originates from the Schiff base bonds [20] This fluorescent Schiff base polymer and the noble metal nanoclusters modified by it have been prepared to fabricate the fluorescent sensors. The recovery of the fluorescence intensity can be realized through the redox reaction between Cr(VI) and Fe(II) ion It is a new “turn-off” fluorescent sensor for Cr(VI) determination, which provides a quantitative approach and offers the speciation of Cr(VI) and Cr(III) as well as Fe(III) and Fe(II)
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