A dual-channel "on-off-on" fluorescent probe for the detection and discrimination of Fe 3+ and Hg 2+ 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 Fe 3+ and Hg 2+ . The probe showed excellent selectivity and sensitivity towards Fe 3+ and Hg 2+ with a dramatic "on-off" fluorescence response. F - recovered the fluorescence quenching by Fe 3+ , and Al 3+ recovered the fluorescence quenching by Hg 2+ , 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 Fe 3+ and Hg 2+ ions. The probe showed wide linear ranges for determination of Fe 3+ (0-100 μM) and Hg 2+ (0-120 μM) with low detection limits of 0.23 μM for Fe 3+ and 0.17 μM for Hg 2+ . This probe was practically applied for the determination of Fe 3+ and Hg 2+ in piggery feed and wastewater with good recoveries. This work provides a fluorescent probe for the quantification of Fe 3+ and Hg 2+ in livestock feed and environmental water samples.