Extraction and Analysis of Auxins in Plants Using Dispersive Liquid-Liquid Microextraction Followed by High-Performance Liquid Chromatography with Fluorescence Detection

Auxin plays an important role in cell differentiation, apical dominance, and tropism in plants. A new method based on dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography-fluorescence detection (HPLC-FLD) has been established to detect auxin. A mixture of CHCl3 (extraction solvent) and acetone (disperser solvent) was injected quickly into a sample solution with desired salt concentration and pH value, and then a cloudy solution consisting of many dispersed fine droplets of CHCl3 was formed. After centrifugation, the sedimented phase was withdrawn and directly analyzed by HPLC-FLD. Under optimal conditions, four auxins were baseline separated within 3.5 min, with the minimal limit of detection of 0.02 ng mL(-1) and coefficient correlations in the range of 0.9980-0.9995. This simple method was successfully applied to real sample analysis. Experimental results showed that DLLME was a high-performance and powerful preconcentration method to extract and enrich related plant auxin.