Ultra-sensitive detection of Cr2O72- in farmland achieved by an electrosynthesized fluorescent poly(Fmoc-succinimide)

Hexavalent chromium (Cr(VI)) pollution is related to human health, and the detection of its concentration has a decisive effect on pollution treatment. In this work, we designed a Cr2O72- sensor P(Fmoc-Osu) and applied it in farmland. In the boron trifluoride diethyl etherate solution, the monomer Fmoc-Osu was electropolymerized and obtained its conjugated polymer P(Fmoc-Osu). The introduction of succinimide and carbonic ester group in side chain enabled it to show high selectivity to Cr2O72- in comparison to anions and twenty amino acids. Furthermore, by taking advantage of the signal amplification effect of a conjugated polymer, P(Fmoc-Osu) could analyze Cr2O72- in trace amounts and the limit of detection was 8.3 fM. For agricultural application, we employed it in farmland water, soil, Chinese cabbage, carrot and the results showed a satisfactory result. All these results showed that P(Fmoc-Osu) is an efficient tool to detect Cr2O72- in practical application.