Simultaneous determination of imidacloprid and carbendazim in water samples by ion chromatography with fluorescence detector and post-column photochemical reactor

A new analytical method has been developed and validated for the simultaneous determination of pesticides from different classes using ion chromatography-online photochemical derivatisation-fluorescence detector (IC- hv -FD). Fluorimetric detection was performed at λ ex / λ em =332   nm/367   nm for imidacloprid and then detector was set at λ ex / λ em =247   nm/470   nm for carbendazim . The two pesticides imidacloprid and carbendazim were successfully separated isocratically on an IonPac ® AS11 (250   mm×4   mm i.d; 13   µm particle size, Dionex) anion-exchange column using 40   mM KOH with 10% (v/v) acetonitrile and pumped at a flow rate of 1.0   mL   min −1 . Under the optimized conditions, the limit of detection (LOD, S/N=3) of imidacloprid and carbendazim were 7.8   µg   L −1 and 67   µg   L −1 , respectively. The experimental results showed that there was good linearity with a correlation coefficient ( r )≥0.9966 over the range of 0.05–10   mg   L −1 for imidacloprid and 0.2–15   mg   L −1 for carbendazim. Good reproducibility with a relative standard deviation (RSD, n =7) less than 4.5%. Finally, the proposed method was applied with satisfactory results to the analysis of these pesticides in ground water, lake water and river water without any pre-treatment of samples. The average spiked recoveries were in the range of 90–104%.