Determination of parathion-methyl in water, juice, tea, and vinegar using cyclodextrin-based dispersive liquid-liquid microextraction combined with smartphone digital image colorimetry

A pre-treatment and analytical procedure for parathion-methyl (PM) in food samples was developed using cyclodextrin-based dispersive liquid-liquid microextraction (CD-DLLME) accompanied by a smartphone digital image colorimetry (SDIC). The extractant used was a green deep eutectic solvent synthesised from hexanoic acid and menthol. Cyclodextrin aqueous solutions were used as the green dispersion solvents to complete the dispersion and extraction process. Thus, a simple, fast, and environmentally friendly pre-treatment method was proposed. PM that was hydrolysed to a yellow product under an alkaline environment, and the colour intensity could be obtained using a smartphone for analysis. PM showed linearity ranging from 0.0020 to 1.0000 mg L-1, with limits of quantification and detection of 0.0020 and 0.0006 mg L-1. This method has been successfully applied in water, juice, tea, and vinegar, with recoveries ranging from 80.4 to 105.7% and relative standard deviation between 1.3 and 3.6%. This method can determine the concentration of PM in different food samples.