Estratégias baseadas em química verde para microextração em fase líquida e determinação de mercúrio em frutos do mar

Abstract

The use of increasingly eco-friendly solvents has been a guiding principle in liquid-phase microextraction (LPME). A solvent can be considered green when it exhibits low toxicity, biodegradability, low cost, and good availability. In this work, two microextraction methods were developed, employing different green solvents for the preconcentration and determination of mercury in seafood samples. In both studies, the reagent ammonium pyrrolidinedithiocarbamate (APDC) was used as a complexing agent, and detection was performed by cold vapor atomic absorption spectrometry (CV AAS). The first study proposes a simple approach based on microextraction with a switchable hydrophilicity solvent (SHS-DLPME). Octanoic acid (C8H16O2) was chosen as the SHS, and sodium carbonate was used as a CO2 source to change the polarity of the extraction solvent. After optimization, the detection limit was 0.010 mg kg-1, and the enrichment factor was 31. The second approach involved a vortex-assisted magnetic deep eutectic solvent dispersive liquid-phase microextraction (VA-MDES-DLPME). The MDES was produced from menthol and octanoic acid, used as proton acceptor and donor, respectively, and incorporated into magnetic iron nanoparticles. For this method, the enrichment factor was 51.4, while the detection limit was 0.009 mg kg-1. Certified reference materials BCR 414 (plankton), BCR 482 (lichen), and ERM-CE 278K (mussel tissue) were used for validation. The methods were applied to determine mercury in fish, mollusk, and crustacean samples, with mercury concentrations ranging from 0.11 to 0.37 mg kg-1 in both methods. The SHS-DLPME and VA-MDES-DLPME methods scored 0.60 and 0.57, respectively, on the AGREE metrics. The results demonstrated that both methodologies align with the principles of green chemistry by providing efficient, selective, and more environmentally friendly alternatives for mercury determination. Overall, the proposed procedures significantly advance sustainable microextraction strategies for contaminant analysis in food.