No abstract

No abstract

This communication shows the improved performance of electrochemically‐reduced graphene oxide (ERGO) modified electrodes for the square‐wave voltammetric detection of cocaine (COC) and its main adulterants paracetamol (PAR), caffeine (CAF) and levamisole (LEV). The four compounds can be identified in a single voltammetric scan on the ERGO‐modified electrode with adequate resolution of peaks and increase in current (at least 2‐fold) in comparison with the unmodified electrode. Moreover, electrode fouling typically verified during the oxidation of CAF and LEV is eliminated. CAF and PAR were determined in a real COC sample and satisfactory recovery values were obtained (103 and 85 %, respectively).

The electrochemical oxidation of dimoxystrobin at a boron-doped diamond electrode is reported. Two well-defined oxidation peaks were observed at around 1350 and 1750 mV in a 0.04 mol L À1 Britton-Robinson buffer solution (pH 10). Based on this electrochemical process, a batch-injection analysis method with amperometric detection was developed for the determination of dimoxystrobin in natural waters. The method presented a high analytical frequency (180 h À1 ), good precision (RSD < 3%, n ¼ 10), and a detection limit of 0.38 lmol L À1 (124 ng mL À1 ). Recovery values obtained using analyte fortified water samples were between 80 and 105%. Additionally, a simple strategy to detect the presence of interfering molecules in water samples based on dual-pulse amperometry is presented.

No abstract

This work presents a portable electrochemical system for the continuous monitoring of corrosion inhibitors in a wide range of matrices including ethanol, seawater and mineral oil following simple dilution of the samples. Proof-of-concept is demonstrated for the sensing of 2,5-dimercapto-1,3,5-thiadiazole (DMCT), an important corrosion inhibitor. Disposable screen-printed graphitic electrodes (SPGEs) associated with a portable batch-injection cell are proposed for the amperometric determination of DMCT following sample dilution with electrolyte (95% v/v ethanol + 5% v/v 0.1molL HSO solution). This electrolyte was compatible with all samples and the organic-resistant SPGE could be used continuously for more than 200 injections (100µL injected at 193µLs) free from effects of adsorption of DMCT, which have a great affinity for metallic surfaces, and dissolution of the other reported SPGE inks which has hampered prior research efforts. Fast (180h) and precise responses (RSD < 3% n = 10) with a detection limit of 0.3µmolL was obtained. The accuracy of the proposed method was attested through recovery tests (93-106%) and the reasonable agreement of results of DMCT concentrations in samples analyzed by both proposed and spectrophotometric (comparative) methods.

No abstract

No abstract