Selectivity and sensitivity enhanced green energy waste based indirect-μ-solid phase extraction of carbaryl supported by DFT and molecular docking studies S. Kanchi a, ⁎, M.I. Sabela a , Mohd Shahbaaz a , N.J. Gumede b , K. Gopalakrishnan c , K. Bisetty a , N. Venkatasubba Naidu d , Inamuddin e,f , Abdullah M. Asiri e,f a Department of Chemistry, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa b Department of Chemistry, Mangosuthu University of Technology, Durban, South Africa c Green Processing, Bioremediation and Alternative Energies Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Viet Nam d Department of Chemistry, Sri Venkateswara University, Tirupati 517 502, India e Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia f Centre of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589, Saudi Arabia abstract article info Article history: Received 11 September 2017 Received in revised form 7 February 2018 Accepted 21 February 2018 Available online xxxx This work reports on a simple, selective, sensitive, rapid and robust spectrophotometric indirect-μ-solid phase ex- traction (ID-μ-SPE) of carbaryl with 4,4′-bis(4-aminophenoxy) benzophenone. These methods were performed in a 5 mL disposable syringe with green energy waste as a solid phase extractor in phosphate buffer medium (pH 8.5). The alkaline hydrolysis of carbaryl resulted 1-naphthol, which interacts with the diazotized 4,4′-bis (4-aminophenoxy) benzophenone to produce red colored product (λ max :450 nm) or interacts with 4,4′-bis(4- aminophenoxy) benzophenone in the presence of an oxidizing agent, Se (IV) to give purple colored product (λ max :545 nm). The obtained colored products were stable for 45 and 63 h respectively. The resulted colored products obey Beer's law in the range of 0.3–12.0 μg mL -1 and 0.3–9.0 μg mL -1 for both methods with detection limits ranging from 0.020–0.022 μg mL -1 . Additionally, the density functional theory calculations and molecular docking studies were performed to explore the stability profiles, intermolecular interactions and related elec- tronic transitions for colored products to complement the experimental results. The developed methods are re- liable and reproducible to detect carbaryl residues in its formulations, waters and food grains. © 2018 Elsevier B.V. All rights reserved. Keywords: 4,4′-Bis(4-aminophenoxy)benzophenone Carbaryl Spectrophotometry Formulations Waters and food grains 1. Introduction Carbaryl (1-naphthyl-N-methylcarbamate) pesticides are frequently sprayed onto rice cultivating crops due to its efficient action against sev- eral pests and to their broad-spectrum of biological activities [1]. It is also used to resist pests on vegetables, cotton, fruits and several differ- ent crops including domestic animals and poultries. However, pesticide residue is one of the burning issues for environmental pollution. In re- cent years farmers spray high dosage of pesticides to increase their yield, which is one of the threats to the environment and human health [2]. According to the European Union and China, the maximum residue limits of several carbamate pesticides in food grains are in the range of 0.02–1 μgg -1 [3] and 0.01–0.1 μgg -1 [4] respectively. Therefore, it is an urgent need to design a method or material to develop a facile, sensitive and reliable method to determine carbaryl residues in differ- ent technical grade and real samples. The literature survey reports indicate that various analytical instru- ments such as GC–MS [5], HPLC [6] and LC-MS [7] have been found to determine carbaryl in various environmental, food and biological sam- ples. However, the above mentioned techniques are highly sophisti- cated and require the specialist to operate the instruments. Recently, few researcher synthesized nanoparticles (NPs) for the determination of carbaryl pesticide residues [8], but suffers from few drawbacks such as usage of harmful chemicals, consumes more time to synthesize NPs and elaborate clean-up procedures (multi-steps) [9]. The crucial step in carbaryl analysis is sample preparation due to its determination in complex solid matrices. Different classical extraction methodologies such as Soxhlet and solvent extraction are adapted from few decades. However, these methods have some disadvantages including, consump- tion of time for sample preparation and requires more sample quantity for extraction or usage of environmentally harmful chemicals [10]. Song and co-workers have proposed a greener extraction route for the eight carbamate pesticides in rice samples. This method was based on the Journal of Molecular Liquids 257 (2018) 112–120 ⁎ Corresponding author. E-mail addresses: ksuvardhan@gmail.com (S. Kanchi), gopalakrishnankumar@tdt.edu.vn (K. Gopalakrishnan), inamuddin@rediffmail.com (Inamuddin). https://doi.org/10.1016/j.molliq.2018.02.099 0167-7322/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Molecular Liquids journal homepage: www.elsevier.com/locate/molliq