Feasibility of supramolecular solvent-based microextraction for simultaneous preconcentration of herbicides from natural waters with posterior determination by HPLC-DAD

A supramolecular solvent-based microextraction procedure for preconcentration of four most common sugarcane herbicides (diuron, hexazinone, ametryn and tebuthiuron) from groundwater and surface water samples with further determination by High Performance Liquid Chromatography with Photodiode Array detector (HPLC-DAD) is proposed. The proposed method involves the use of a supramolecular solvent in which reverse micelles of 1-decanol are dispersed in tetrahydrofuran/water. The extraction of four herbicides performed at pH 4.0 requires low sample volume (10.0 mL), low extraction time (30 s of extraction and 10 min of centrifugation), low amount of organic solvents (50 μL of 1-decanol and 100 μL of THF) and provides high preconcentration factors (48.5 to diuron, 15.1 to hexazinone, 47.4 to ametryn and 21.0 to tebuthiuron). The limits of detection (LOD), quantification (LOQ), the precision (RSD) and the accuracy (RE) of the developed method ranged between 0.13 and 1.45 μg L− 1, 0.43-4.85 μg L− 1, 2.4-6.8% and 0.6-6.2%, respectively. Recovery values obtained by applying the proposed method in spiked groundwater and surface water samples at μg L− 1 levels varied in the range of 95-111%. The quantification of some analyzed herbicides in natural waters showed clearly the importance of investigates herbicides concentrations in regions of sugarcane cultivation predominance.