Novel magnetic deep eutectic solvent/Zn-MOF composite for extraction of Carmoisine from water and food samples

In the current research, a novel magnetic deep eutectic solvent was first introduced. Afterwards, Zn-based metal organic framework (Zn-MOF) and a unique magnetic deep eutectic solvent were combined to successfully create the novel composite as an effective adsorbent. Subsequently, this innovative composite exhibiting outstanding characteristics was employed to solid phase extraction of Carmoisine dye (as a model analyte) from water and food samples, followed by spectrophotometric determination. According to the structure of the analyte and newly synthesized composite, π-π interaction between the aromatic rings of the Carmoisine and composite, as well as electrostatic interaction between the sulfonate groups of the analyte and nitrogen of the amine group in the deep eutectic solvent, could be the main mechanism for analyte adsorption. Under optimal extraction conditions (pH;6.0, Adsorption time; 2.5 min, Adsorbent amount; 10.0 mg, Desorption solution; EtOH/0.5 M HNO3, Desorption time; 2.0 min, Desorption volume; 1.0 mL, and sample volume; 35.0 mL), the preconcentration factor of 35.0 was obtained. The calibration curve also was linear in the range of 10.0 to 700 μg L-1 with coefficients of determination (R2) of 0.9987. The limit of detection (LOD), the limit of quantification (LOQ), intra-day relative standard deviation (RSD)%, and inter-day RSD% were obtained at 2.4 μg L-1, 8.3 μg L-1, 4.2%, and 6.6%, respectively. The extraction recovery of 98.24 and the relative recovery in the range of 92.3%-99.8% were obtained. The proposed adsorbent offers several advantages, including easy synthesis using inexpensive materials, a 2-hour surface modification for magnetic nanoparticles, successful extraction of the model analyte in a variety of real samples due to different functional groups and aromatic rings on the adsorbent structure, and stability of the sorbent in pH ranges of 2 to 10. Consequently, it is highly recommended for future research as an effective adsorbent for extraction and separation purposes.