(a) Emission
spectra of the C-CD solution in the presence of 190
μM concentration of Pb2+, K+, Fe3+, Cd2+, Mn2+, Zn2+, In3+, Cu2+, Ce3+, and Mg2+. (b) Relative
fluorescence intensity of C-CDs (where I and I0 are the intensities in the presence and absence
of the metal ions, respectively). (c) Emission spectra of C-CD solution
in the presence of 190 μM concentration of BH4–, IO3–, SeO32–, PO43–, SO32–, B4O72–, HPO42–, CO32–, Cl–, HCO3–, OH–, MoO42–, SO42–, H2PO4–, CH3COO–, and NO3–. (d) Relative fluorescence intensity of C-CDs (where I and I0 are the intensities in the presence
and absence of the anions ions, respectively). (e) Quenching of the
fluorescence intensity of the C-CD solution in different concentrations
of the Fe3+ solution. (f) Plot of (I0 – I)/I0 with different Fe3+ concentrations. Ex = 330 nm; Em = 415 nm; and
slit widths of both excitation and emission = 2.5. The results are
the average and standard deviation of four replicates of the measurements.