Biodiesel as a green alternative solvent in dispersive liquid-liquid microextraction

Biodiesel, a fuel derived from renewable sources, is a nonpolar liquid, composed of alkyl esters derived from long-chain carboxylic acids. Because of its environmental friendliness, large-scale production, and cost-effectiveness, biodiesel is herein proposed as a green solvent for liquid-liquid microextraction. Its potential has been demonstrated through the extraction of model analytes, with varying polarities through analytical measurements performed by smartphone-based digital images. Partition coefficients biodiesel/water (log P) were –0.45 (pH 2.0) for crystal violet, –1.3 (pH 7.0) for bromocresol green, 1.05 for PAN, 3.48 for Cu(II)-PAN complex, and 2.14 for quercetin. Biodiesel was effective in extracting nonpolar species, with extraction efficiencies of 90 % for PAN, 99 % for quercetin and Cu(II)-PAN complex. Efficiency of extraction of the Cu(II)-PAN complex increased in the following order: chloroform, ethyl acetate, and biodiesel, and the highest recoveries were achieved with biodiesel as solvent. Only slightly variations in the extraction efficiency was observed from biodiesel produced from different feedstock. Biodiesel was also efficient for extraction of the ion-pairs from anionic surfactants and methylene blue, with the perspective of replacing chloroform in this classical method. The results showed that biodiesel is an efficient alternative solvent to replace typical toxic solvents, with greenness demonstrated through the Green Star and AGREE metrics.