Micellar Electrokinetic Chromatography Method Development for Sensitive Monitoring of Rotenone in Lake Waters

Rotenone, a naturally occurring isoflavone compound, is applied to water as a piscicide to manage undesired fish populations in lakes, ponds, rivers and in aquaculture. A rapid and sensitive method based on solid-phase extraction (SPE) combined with large-volume sample stacking with polarity switching (LVSS) and micellar electrokinetic chromatography (MEKC) has been developed for the identification and quantification of rotenone in lake water. Several experimental parameters for MEKC, LVSS and SPE were investigated to achieve the optimum conditions necessary for the analysis. The optimized conditions which included a background electrolyte containing 20 mM sodium borate and 25 mM sodium dodecyl sulfate (SDS) at pH 10 were used to successfully detect rotenone within 17 min. Using a combined SPE and LVSS approach, the rotenone signal was enhanced by 1000-fold compared with a normal capillary electrophoresis analysis, and limits of detection and quantification obtained were 3 and 10 μg L −1 , respectively. The calibration curve was linear for rotenone concentration over the range of 10–100 μg L −1 and the method was highly reproducible with the relative standard deviation of the peak areas and migration times for method intra-day repeatability ( n = 6) found to be 5.4% and 0.6%, respectively. Quantitative recoveries ranging from 85 to 88% were obtained in the lake water matrices. The potential of the proposed method to be used for quantitative determination of rotenone at trace level concentrations in water samples was demonstrated by analyzing lake water samples including surface (1 m) and bottom (13 m), which makes it a suitable practical method for analyzing rotenone residues in water.