Search

We report the development of a simple, portable, low-cost, high-throughput visual colorimetric paper-based analytical device for the detection of procaine in seized cocaine samples. The interference of most common cutting agents found in cocaine samples was verified, and a novel electrochemical approach was used for sample pretreatment in order to increase the selectivity. Under the optimized experimental conditions, a linear analytical curve was obtained for procaine concentrations ranging from 5 to 60 μmol L-1, with a detection limit of 0.9 μmol L-1. The accuracy of the proposed method was evaluated using seized cocaine samples and an addition and recovery protocol. [ABSTRACT FROM AUTHOR]

A wearable electrochemical sensor for non-invasive monitoring of trace metals in human perspiration is described. The temporary tattoo-based printable stripping-voltammetric sensor has been applied for real-time monitoring of zinc in sweat using a bismuth/Nafion film electrode during physical activity. The Zn temporary tattoo sensor withstands repeated mechanical stress and displays a well-defined Zn response during on-body testing. Such a non-invasive stripping-voltammetric detection could be readily expanded to epidermal measurements of other relevant heavy metals. [ABSTRACT FROM AUTHOR]

Abstract: We report the development of a simple analytical method that offers reagentless sensing capabilities by using a copper sensor for monitoring melamine. In this method, the anodic dissolution of the copper electrode is initiated electrochemically to release copper ions, which form the melamine chloride copper ionic pair at the electrode surface. After this process, the melamine chloride copper ionic pair can be reduced electrochemically at the surface of the electrode and quantified under the optimized conditions. This protocol eliminates the necessity to contaminate the sample with a copper salt, making the method proposed herein more environmentally benign than other techniques. The elucidation of the electrochemical reduction process of the melamine copper ionic pair was investigated with an electrochemical quartz crystal microbalance (EQCM). The quantification of melamine in milk was performed using differential pulse voltammetry, where the peak current response was found to increase linearly with melamine concentration over the range 5–90μmolL−1. The repeatability of the electrode response was evaluated as 1% (n=20), and the detection limit of the proposed method was estimated to be 0.85μmolL−1 (3σ/slope). The accuracy of the proposed method was evaluated using milk samples and an addition and recovery protocol. [Copyright &y& Elsevier]

Abstract: A simple and fast electrochemical method for quantitative analysis of picric acid explosive (nitro-explosive) based on its electrochemical reduction at copper surfaces is reported. To achieve a higher sample throughput, the electrochemical sensor was adapted in a flow injection system. Under optimal experimental conditions, the peak current response increases linearly with picric acid concentration over the range of 20–300μmolL−1. The repeatability of the electrode response in the flow injection analysis (FIA) configuration was evaluated as 3% (n=10), and the detection limit of the method was estimated to be 6.0μmolL−1 (S/N=3). The sample throughput under optimised conditions was estimated to be 550 samplesh−1. Peroxide explosives like triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) were tested as potential interfering substances for the proposed method, and no significant interference by these explosives was noticed. The proposed method has interesting analytical parameters, environmental applications, and low cost compared with other electroanalytical methods that have been reported for the quantification of picric acid. Additionally, the possibility to develop an in situ device for the detection of picric acid using a disposable sensor was evaluated. [Copyright &y& Elsevier]