title: Rapid and molecular selective electrochemical sensing of phthalates in aqueous solution.
abstract: Reported research work presents real time non-invasive detection of phthalates in spiked aqueous samples by employing electrochemical impedance spectroscopy (EIS) technique incorporating a novel interdigital capacitive sensor with multiple sensing thin film gold micro-electrodes fabricated on native silicon dioxide layer grown on semiconducting single crystal silicon wafer. The sensing surface was functionalized by a self-assembled monolayer of 3-aminopropyltrietoxysilane (APTES) with embedded molecular imprinted polymer (MIP) to introduce selectivity for the di(2-ethylhexyl) phthalate (DEHP) molecule. Various concentrations (1-100 ppm) of DEHP in deionized MilliQ water were tested using the functionalized sensing surface to capture the analyte. Frequency response analyzer (FRA) algorithm was used to obtain impedance spectra so as to determine sample conductance and capacitance for evaluation of phthalate concentration in the sample solution. Spectrum analysis algorithm interpreted the experimentally obtained impedance spectra by applying complex nonlinear least square (CNLS) curve fitting in order to obtain electrochemical equivalent circuit and corresponding circuit parameters describing the kinetics of the electrochemical cell. Principal component analysis was applied to deduce the effects of surface immobilized molecular imprinted polymer layer on the evaluated circuit parameters and its electrical response. The results obtained by the testing system were validated using commercially available high performance liquid chromatography diode array detector system.
authors.affiliation: School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand; Department of Physics, COMSATS Institute of Information Technology, Islamabad, Pakistan. Electronic address: a.i.zia@me.com.
authors.forename: Asif I
authors.initials: AI
authors.lastname: Zia
authors.affiliation: School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand.
authors.forename: Subhas Chandra
authors.initials: SC
authors.lastname: Mukhopadhyay
authors.affiliation: School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand.
authors.forename: Pak-Lam
authors.initials: PL
authors.lastname: Yu
authors.affiliation: School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand.
authors.forename: I H
authors.initials: IH
authors.lastname: Al-Bahadly
authors.affiliation: Sensing, Magnetism and Microsystems Group, King Abdullah University of Science and Technology, Saudi Arabia.
authors.forename: Chinthaka P
authors.initials: CP
authors.lastname: Gooneratne
authors.affiliation: Sensing, Magnetism and Microsystems Group, King Abdullah University of Science and Technology, Saudi Arabia.
authors.forename: J Rgen
authors.initials: JR
authors.lastname: Kosel
mesh_terms: D015374:Biosensing Techniques; D058266:Dielectric Spectroscopy; D004051:Diethylhexyl Phthalate / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D054802:Molecular Imprinting; D010795:Phthalic Acids / Q000737:chemistry / Q000302:isolation & purification*; D011108:Polymers / Q000737:chemistry*; D011437:Propylamines; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D012996:Solutions / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D010795:Phthalic Acids; D011108:Polymers; D011437:Propylamines; D012821:Silanes; D012996:Solutions; D014867:Water; C032279:phthalic acid; D006046:Gold; D012822:Silicon Dioxide; D004051:Diethylhexyl Phthalate; C477625:amino-propyl-triethoxysilane
keywords: Constant Phase Element; DEHP; Electrochemical; Impedance spectroscopy; Interdigital sensors; Phthalates