Novel Solid-State Potentiometric Sensors Using Polyaniline (PANI) as A Solid-Contact Transducer for Flucarbazone Herbicide Assessment

Novel potentiometric solid-contact ion-selective electrodes (SC/ISEs) based on molecularly imprinted polymers (MIPs) as sensory carriers (MIP/PANI/ISE) were prepared and characterized as potentiometric sensors for flucarbazone herbicide anion. However, aliquat S 336 was also studied as a charged carrier in the fabrication of Aliquat/PANI/ISEs for flucarbazone monitoring. The polyaniline (PANI) film was inserted between the ion-sensing membrane (ISM) and the electronic conductor glassy carbon substrate (GC). The sensors showed a noticeable response towards flucarbazone anions with slopes of −45.5 ± 1.3 (r2 = 0.9998) and −56.3 ± 1.5 (r2 = 0.9977) mV/decade over the range of 10−2–10−5, 10−2–10−4 M and detection limits of 5.8 × 10−6 and 8.5 × 10−6 M for MIP/PANI/ISE and Aliguat/PANI/ISE, respectively. The selectivity and long-term potential stability of all presented ISEs were investigated. The short-term potential and electrode capacitances were studied and evaluated using chronopotentiometry and electrochemical impedance spectrometry (EIS). The proposed ISEs were introduced for the direct measurement of flucarbazone herbicide in different soil samples sprayed with flucarbazone herbicide. The results agree well with the results obtained using the standard liquid chromatographic method (HPLC).

An evaluation technique for high-frequency dynamic behavior of a sandwich microcantilever beam

A method was developed to measure the first- and second-order vibration modes in a sandwich microcantilever beam oscillating in the megahertz frequency regime in the present study. Taking advantage of the ultrasonic frequency, a test platform was developed to induce free vibration of the microcantilever using a high-power radio frequency pulser that transmits tone burst signals to a contact transducer, and the resonant frequencies of the microcantilever were measured using a laser-optic interferometer. Results show that the microcantilever’s vibration above 8 MHz can be successfully detected, and its vibration modes were identified through a theoretical study based on the Euler–Bernoulli beam theory and a numerical analysis using the finite element method. The present study proposes a facile and effective way to actuate a high-speed sandwich microcantilever and detect its high-frequency response so that the technique can be employed to study the characteristics of micro- and nanomechanical sandwich structures and their properties.

Impact Induced Damage Detecting of Aircraft CFRP Covering by Acoustic Testing

Aircraft parts made of composite materials are susceptible to impact damage which can be negligible visually but significantly worsening their strength. Finding such damage requires periodic monitoring of large areas of the surface of the aircraft airframe. Fundamentally, such monitoring is possible by using active thermography or acoustic methods. Acceptable to practice, this task can be solved by scanning the surface with a rolling dry-point contact transducer array, and by analysis of Lamb wave signals propagating through the monitored material between the array adjacent transducers. This paper presents a device based on this principle, the signal analysis algorithm, and the images recomposed by the device during composite material testing. The developed equipment provides on-line inspection of impact-induced damage in aircraft covering made of composite materials. However, complex type of generated images requires constant monitoring of the covering state of each aircraft during its operation.

Pulsed chronopotentiometric membrane electrodes based on plasticized poly(vinyl chloride) with covalently bound ferrocene functionalities as solid contact transducer

Ion-selective membrane materials based on poly(vinyl chloride) (PVC)-containing covalently attached redox-active ferrocene (Fc) groups are characterized here as all-solid-state pulsed voltammetric ion sensors. The redox capacity of the membrane increases 7-fold with a doubling of the Fc content and 3-fold with the addition of 10 wt % of the lipophilic electrolyte ETH 500, tetradodecylammonium tetrakis(4-chlorophenyl)borate. This salt improves the ionic conductivity of the membrane and appears to make the Fc groups electrochemically more accessible. A too high content of the two, on the other hand, was found to cause undesired sensitivity to redox-active species present in the sample solution. Dilution of the membrane with a plasticizer eliminated this redox sensitivity while preserving its high redox capacity. A practical application of the designed electrodes in electrochemical analysis was demonstrated with a multi-pulse protocol that includes a current-controlled ion uptake pulse, followed by an open-circuit potential (OCP) measurement and a regeneration pulse. Potentiometric calibration curves obtained with this protocol exhibited a linear response with near-Nernstian slopes for acetate, nitrate, chloride, and perchlorate ions with the selectivity expected for an ion-exchanging membrane.

Preface

The 14th Asian Chemical Congress (14 ACC) was held in Bangkok, Thailand 5-8 September 2011 by the Chemical Society of Thailand (CST) under the patronage of Prof. Dr. Her Royal Highness Princess Chulabhorn. The congress was supported as a tradition hosted by the members of the Federation of Asian Chemical Societies (FACS) and sponsored by IUPAC. The congress was a unique and exciting forum for meeting the challenge put forth by the event's theme: "Contemporary chemistry for sustainability and economic sufficiency". The congress attracted more than 1800 scientists from 48 different countries. Two Nobel Laureate lectures, a Kavli Foundation lecture, 6 plenary lectures, and FACS Award lectures were delivered, and 183 invited papers and approximately 1000 contributed scientific papers were presented in 23 symposia, 45 concurrent sessions, and poster presentations.In order to meet the significance of the theme of the congress and to celebrate the International Year of Chemistry 2011, this issue of Pure and Applied Chemistry collects seven selected articles from invited lectures delivered at the congress to highlight "Sustainability and economic sufficiency: Novelty in green analytical chemistry". These articles are: "Pulsed chronopotentiometric membrane electrodes based on plasticized poly(vinyl chloride) with covalently bound ferrocene functionalities as solid contact transducer" (Eric Bakker); "Laboratory automation based on flow techniques" (Victor Cerda); "Chemiluminescence immunoassay for a nonionic surfactant using a compact disc-type microfluidic platform" (Toshihiko Imato); "Cauliflower polyaniline/multiwalled carbon nanotubes electrode and its applications to hydrogen peroxide and glucose detection" (Proespichaya Kanatharana); "More with less: Advances in flow and paper-based monitoring of nutrients in aquatic systems" (Ian D. McKelvie); "Computer-controlled flow chemical analysis (CC-FCA) and its application to environmental analytical chemistry" (Shoji Motomizu); and "Reagent-free analytical flow methods for the soft drink industry: Efforts for environmentally friendly chemical analysis" (Duangjai Nacapricha).Other general papers presented in the congress were published in the 14 ACC Proceedings.We certainly acknowledge the great contribution made to this congress by the Congress Chair, Prof. Supawan Tantayanont, as well as the local organizing and scientific committees. We also thank the different organizers and session chairs for the symposia and workshops, which were exhibited in a lively manner during this successful congress, and the contributors to this issue.The 15th ACC is scheduled to be held 19-23 August 2013 in Singapore.Supa Hannongbua and Kate GrudpanConference Editors