Detection of Amaranth and Iron in Foods by Modified Carbon Quantum Dots as a Ratiometric Fluorescence Probe

Abstract In this work, a new carbon quantum dots (CDs) was prepared though microwave assisted approach using citric acid anhydrous (CA) and N‐[3‐(Trimethoxysilyl)propyl] ethylenediamine (TPED) as raw materials. However, the CDs was not effective in actual sensing applications, so further modification of CDs was done by 3,5‐Dichloro‐2‐hydroxybenzaldehyde (it was named as G‐CDs). Fortunately, the modified CDs (G‐CDs) has good selectivity for Fe 3+ and amaranth. Studies confirmed that Fe 3+ could quench the fluorescence of G‐CDs by forming a complex, while the fluorescence quenching mechanism of G‐CDs by amaranth (AM) mainly belonged to the internal filtering effect (IFE). A detection limit of 20.8 nM for Fe 3+ and 43.8 nM for AM were achieved. Moreover, the as‐developed G‐CDs probe was also successfully used to detect Fe 3+ and amaranth in real samples, and compared with their results by the standard method, hinting that the accuracy and reliability of the probe were highly satisfactory.