Micelle-mediating Extraction Combined with Visible Spectrophotometry for the Determination of Ultra Trace Amounts of Bendiocarb Insecticide in Various Matrices after Oxidative Coupling with O-Toluidine

Aims: To develop a new eco-friendly method for the extraction and pre-concentration of Bendiocarb (BC) in real samples by using micelle-mediating extraction (MME) coupled with visible spectrophotometry after oxidative coupling with O-Toluidine.

Study Design: All factors affecting the extraction and determination of BC using micelle-mediation extraction were performed by a classical optimization; in addition the interferences study is also studied.

Place and Duration of Study: Department of Chemistry, College of Science for Women, University of Baghdad, Baghdad, Iraq between May 2015 and September 2015.

Methodology: The developed method is based on an alkaline hydrolysis of BC, and the resultant hydrolyzed phenol is reacted with O-Toluidine in the presence of sodium periodate as an oxidizing agent to form yellow colored product which then extracted into micelles of Triton X-114 as a mediated extractant. The extracted product in cloud point layer is separated from the aqueous one by centrifugation for 20 min and dissolved in a minimum amount of ethanol: water (1:1) followed the determination of BC by using spectrophotometry at a wavelength maximum of 430 nm. The established method was applied to the analysis of the spiked vegetables, orange, soil and water samples with appropriate concentrations of BC standard. .

Results: At the established optimized conditions, an enrichment factor of 121.6 fold is obtained leading to achieve the limit of detection of 0.44 ng mL-1 with Beer’s law concentration range of 2-22 ng mL-1, and the effective optimum linear range of 4.5-21.3 ng mL-1 determined by Ringbom’s plot. The proposed method gives superior sensitivity in terms of the molar absorptivity of 1.02x107 L mol-1 cm-1 and extraction efficiency of 97.2%. The average percent recovery of 97.95±1.57%, and a precision (RSD%, n=5) in the range of 0.19-1.56% in real samples are obtained.

Conclusion: The proposed method offers excellent analytical figures of merits such as a limit of detection, high sensitivity, good accuracy and precision and relatively interferences-free compared to the previously reported methods in chemical literatures. It can be considered as an alternative to the other sophisticated techniques such as LC-MS, GC-MS and electrophoresis.