On-line concentration in micellar electrokinetic chromatography for triazine determination in water samples: evaluation of three different stacking modes

Abstract

Three different stacking modes for the on-line concentration of seven selected triazines (desisopropylatrazine, desethylatrazine, simazine, hydroxyatrazine, atrazine, propazine and prometryn) by micellar electrokinetic chromatography (MEKC) were evaluated, namely the normal stacking mode, field enhancement sample injection and reverse electrode polarity stacking mode (REPSM). The best results were obtained using REPSM at –20 kV for 90 s. Concentration factors from 4 to 10 were achieved and the detection limits varied within the range 3.3–8.5 μg l−1. This methodology was combined with a solid-phase extraction (SPE) procedure to allow the determination of these analytes at trace levels. The SPE-REPSM-MEKC method developed was validated with a certified reference material of pesticides in drinking water (CRM 606) and was applied to the determination of the selected triazines in drinking waters at the level required by the European Union (0.1 μg l−1).