Directly suspended-solidified floating organic droplets for the determination of fungicides in water and honey samples

A directly suspended-solidified floating organic droplet microextraction (DS-SFO) method was developed for the preconcentration of four fungicides (i.e., chlorothalonil, triadimefon, cyprodinil, and trifloxystrobin) from water and honey samples prior to HPLC-DAD detection. In this technique, no special devices or supporting materials are required. The extraction phase can be easily collected via solidification of the microdroplet after the desired extraction time. The experimental parameters affecting the extraction efficiency were investigated and optimized, which resulted under optimal conditions of a 20 μL microdroplet of 1-dodecanol as the organic extractant, 3 mL of water or diluted honey sample without salt addition, and 90 min of stirring at 900 rpm and 30 °C. Under the optimized conditions, the proposed method achieved high extraction recoveries of 80% to 93% and 70% to 83% for water and honey samples, respectively. The limits of detection (LOD) of the method were in the range of 0.20-1.95 ng mL^-1 for water samples and 1.14-11.06 ng g^-1 for honey samples. The relative standard deviation (RSD) was <9.2% for both samples. Good linearities (r > 0.9980) over the calibration range of 5-1000 ng mL^-1 were obtained. This method allowed the use of green solvents, a minimal usage of organic solvents, simple device and extraction processes, and high-throughput operations. Finally, the proposed method was successfully applied to the determination of fungicides in real water and honey samples.