A sensitive and efficient method for the determination of 8 chlorophenoxy acid herbicides in crops by dispersive liquid-liquid microextraction and HPLC with fluorescence detection and identification by MS

A simple sample pretreatment method of dispersive liquid-liquid microextraction (DLLME) was developed for fast and efficient extraction of 8 chlorophenoxy acid herbicides (CPAHs). The extracted CPAHs were labeled with a sensitive derivatization reagent and measured by high performance liquid chromatography-fluorescence detection (HPLC-FLD). Good linear correlations were obtained for all analytes with R-2 > 0.9999. The limits of detection (LODs) were <0.79 ng mL (1) relatively lower than those of other analysis methods. The intra-day and inter-day precisions of the CPAHs were under 3.1% and 4.6%, respectively. Recoveries of each of the CPAHs from spiked millet and pepper samples were in the range of 90-103.2%. The simplicity of the procedure, high extraction efficiency, short analysis time and the low detection limits suggest that the proposed method has a potential for routine CPAH analysis in biological samples.