Determination of carbamate pesticides in water and fruit samples using carbon nanotube reinforced hollow fiber liquid-phase microextraction followed by high performance liquid chromatography

A new method has been developed for the determination of five carbamate pesticides (metolcarb, carbofuran, carbaryl, isoprocarb, diethofencarb) in water and fruit samples by using carbon nanotube reinforced hollow fiber-liquid phase microextraction (HF-LPME) prior to high performance liquid chromatography-diode array detection (HPLC-DAD). Parameters that could affect the extraction efficiencies, such as the type of the organic extraction solvent and its volume, the type and concentration of multi-walled carbon nanotubes (MWCNTs), fiber length, extraction time, the pH of the sample solution, stirring rate and ionic strength, were investigated and optimized. Under the optimal extraction conditions, the linearity was observed in the range of 0.5-300 ng mL(-1) for water samples and 1-300 ng g(-1) for fruit samples, with the correlation coefficients (r) of 0.9992-0.9999 and 0.9996-0.9998, respectively. The enrichment factors (EFs) obtained were between 75 and 119, and the limits of detection (LODs) were 0.1-1.0 ng mL(-1) for water samples and 0.2-2.0 ng g(-1), for fruit samples. The recoveries for the spiked samples were in the range of 77.5%-104.4%, and the precision values, expressed as the relative standard deviations (RSDs), were in the range between 2.9% and 9.2%. The results demonstrated that the newly developed method was an efficient pretreatment and enrichment procedure for the determination of carbamate pesticides in water and fruit samples.