Encapsulation of amaranth CDs at ZIF-7 MOFs as a novel adsorbent for ultrasonic-assisted dispersive nano-solid-phase microextraction and ultrasensitive determination of allura red in food samples

Allura Red AC (AR) can be used in foodstuffs to give them a pleasant taste, color, appearance, stability, and smell. High consumption of the dye has been associated with adverse health effects. A sensitive method, namely ultrasound-assisted coupled dispersive nano solid-phase micro-extraction spectrophotometry (UA-DNSPMEUV-Vis) was designed for AR as food colorant preconcentration and determination in real samples. The method is based on the first-time usage of amaranth carbon dot@Zn (II) organic framework comprising benzimidazole (ZIF7) composite. The characterization of the synthesized CD@MOF was performed using XRD, SEM, FTIR, HRTEM, EDX, SAED, UV-Vis absorption, and fluorescence. Among conventional parameters including pH, amount of sorbent, sonication time and type and volume of elution solvent was examined. The established method showed excellent linearity over the range of 0.30 - 7.00 nM. Anions and cations were also studied for their interference effect. The preconcentration factor was 85, with 0.60 nM LOD. As-synthesized nanocomposite had significant adsorption capacity and reusability. Analysis of some real samples showed satisfactory results in the range of 8.41 to 2953 mM for liquid food samples and from 2.95 to 5.88 mM for solid food samples with a satisfactory range of recovery values from 98.44 to 102.41 %.

Automated summary

A sensitive method, ultrasound-assisted coupled dispersive nano solid-phase micro-extraction spectrophotometry, was designed for preconcentration and determination of the food colorant Allura Red AC in real samples. The method showed excellent linearity and high reusability.