A dual-channel “on–off–on” fluorescent probe for the detection and discrimination of Fe3+ and Hg2+ in piggery feed and swine wastewater

Blue-fluorescent blood-CDs were synthesized through a one-pot hydrothermal method using a mixture of chicken blood and trisodium citrate and then explored as a fluorescent probe for detecting Fe3+ and Hg2+. The probe showed excellent selectivity and sensitivity towards Fe3+ and Hg2+ with a dramatic “on–off” fluorescence response. F− recovered the fluorescence quenching by Fe3+, and Al3+ recovered the fluorescence quenching by Hg2+, showing an “off–on” fluorescence response. The blood-CDs were used as an “on–off–on” dual-channel fluorescent sensor for the detection and discrimination of Fe3+ and Hg2+ ions. The probe showed wide linear ranges for determination of Fe3+ (0–100 μM) and Hg2+ (0–120 μM) with low detection limits of 0.23 μM for Fe3+ and 0.17 μM for Hg2+. This probe was practically applied for the determination of Fe3+ and Hg2+ in piggery feed and wastewater with good recoveries. This work provides a fluorescent probe for the quantification of Fe3+ and Hg2+ in livestock feed and environmental water samples.