Enhancement of sensitivity for the spectrophotometric determination of carbaryl using dispersive liquid microextraction combined with dispersive μ-solid phase extraction
This work reports a sensitive spectrophotometric method for the determination of carbaryl (CBR). The method is based on the extraction of CBR using a two-step microextraction method, dispersive liquid microextraction (DLME) combined with dispersive micro-solid phase extraction (D-μ-SPE) before its detection by spectrophotometry. 1-Octanol was used as the extractant in DLME. For the D-μ-SPE method, magnetic nanoparticles (Fe3O4) functionalized with 3-aminopropyl-triethoxysilane (APTS) were used as the adsorbent to interact with the 1-octanol in DLME. The extracted CBR was spectrophotometrically detected at 480 nm after its derivatization with 2-naphthylamine-1-sulfonic acid (ANSA). The factors affecting the extraction were investigated in detail. The optimal conditions for the DLME were 150 μL of 1-octanol and vortex speed of 3200 rpm for 2 min. For the D-μ-SPE, APTS magnetic nanoparticles (10 mg) was used as the adsorbent, acetonitrile was used as the desorption solvent and the optimum time for desorption was 4 min sonication. The enrichment factor obtained was 2730. The linear range was 10–100 ng mL−1, the limit of detection was 8 ng mL−1, while the limit of quantitation was 26 ng mL−1 and the relative standard deviation was 8.5% from five replicates. The recovery of CBR from three spiked concentration levels of 25, 50 and 75 ng mL−1 was 97.3–108.1%. The method was successfully applied for the determination of CBR in tap water, field water and fruit juice samples. The proposed method has high potential to be used as an efficient preconcentration method for CBR. The APTS magnetic nanoparticles can be reused 10 times with high extraction efficiency.