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
Zuhair A-A Khammas *
Department of Chemistry, College of Science for Women, University of Baghdad, Jadiyriah, Baghdad, Iraq
Suher S. Ahmad
Department of Chemistry, College of Science for Women, University of Baghdad, Jadiyriah, Baghdad, Iraq
*Author to whom correspondence should be addressed.
Abstract
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.
Keywords: Bendiocarb pesticide, O-toluidine, oxidative coupling reaction, cloud point extraction, UV-Vis spectrophotometry