Determination of aldicarb, carbofuran and some of their main metabolites in groundwater by application of micellar electrokinetic capillary chromatography with diode-array detection and solid-phase extraction

This paper describes a UV detection method for the pesticides aldicarb and carbofuran, and some of their main metabolites, aldicarb-sulfoxide, aldicarb-sulfone and 3-hydroxy-carbofuran, in ground waters. Micellar electrokinetic chromatography (MEKC) with diode-array detection was developed for their determination at 210 nm. The experimental study was performed using sodium dodecyl sulfate (SDS) at a concentration level of 140 mM, and a buffer of borax/HCl 20 mM at pH 8 which gives the best resolution with an analysis time of less than 20 min. Different instrumental parameters such as voltage (23 kV), injection time (12 s) and temperature (25degreesC) were optimized. The detection limits were in the range 2-7.4 mug litre(-1) by solid-phase extraction (SPE) with a subsequent evaporation step. Groundwater spiked samples were pre-concentrated off-line with graphite carbon and subsequently analyzed by MEKC with diode-array detection yielding average recoveries between 77 and 97% (n = 4) with RSD between 2-7%. (C) 2004 Society of Chemical Industry.