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MEKC combined with SPE and sample stacking for multiple analysis of pesticides in water samples at the ng/L level

In this work, a new multiresidue analytical method based on MEKC with UV detection combined with SPE as off‐line preconcentration strategy, and reversed‐electrode polarity stacking mode (REPSM) as on‐line stacking procedure, has been developed for the monitoring of 12 pesticides (carbendazim, pirimicarb, metalaxyl, pyrimethanil, procymidone, nuarimol, azoxystrobin, tebufenozide, fenarimol, benalaxyl, penconazole, and tetradifon) that are currently being used in the Canary Islands (Spain). The optimized MEKC buffer, consisting of 100 mM sodium tetraborate and 30 mM SDS at pH 8.5 with 6% v/v 1‐propanol, provided baseline resolution of the 12 pesticides in less than 20 min. The developed method was applied to the analysis of mineral, stagnant, and tap water samples. The proposed SPE‐REPSM‐MEKC‐UV method showed high extraction efficiencies with detection limits (LODs) at the low ng/L level providing LOD values down to 64 ng/L for these real samples.