Correction: Exploring the origins of the apparent "electrocatalytic" oxidation of kojic acid at graphene modified electrodes (Analyst (2013) 138 (4436-4442))

The text that appears on page 4437 under the heading ‘Experimental section’ that reads: ESI Fig. S1A† depicts a typical Transmission Electron Microscope (TEM) image of the commercially purchased graphene and ESI Fig. S1B† shows a high resolution TEM image where a hexagonal arrangement of carbon atoms, which is characteristic of graphene, is clearly evident. should be changed to: ESI Fig. S1A† depicts a typical TEM image of a graphene sheet that has been fabricated using the same method as our commercially sourced graphene and Fig. S1B† shows a high-resolution TEM image (from the same source) where a hexagonal arrangement of carbon atoms, which is characteristic of graphene, is clearly evident. Independent TEM and Raman analysis of the commercially sourced graphene (as received from the supplier and consequently as used throughout this work) is presented in Fig. S3 and S4† respectively. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers

Exploring the origins of the apparent "electrocatalytic" oxidation of kojic acid at graphene modified electrodes

We explore the recent reports that the use of graphene modified electrodes gives rise to the electrocatalytic oxidation of kojic acid. It is demonstrated that large quantifiable voltammetric signatures are observed on bare/unmodified graphitic electrodes, which are shown to be analytically useful and superior to those observed at graphene modified alternatives. This work is of importance as it shows that control experiments are critical and must be undertaken before "electrocatalysis" is conferred when investigating graphene in electrochemistry. In terms of the electroanalytical response of graphene modified electrodes, a bare edge plane pyrolytic graphite electrode is shown to give rise to an improved linear range and limit of detection, questioning the need to modify electrodes with graphene. © 2013 The Royal Society of Chemistry

Electroanalytical thread-device for estriol determination using screen-printed carbon electrodes modified with carbon nanotubes

Microflow systems are powerful analytical tools that explore similar principles of typical flow injection analysis driven to in a microfluidic device. Generally, microfluidic devices can promote a low consumption of reagents and samples, high speed of analysis and possibility of portability. Several advances have been reached applying a simple and low cost device based on cotton thread as microfluidic channel where the transportation of solutions is based on capillary force helped by gravity. In the present work, we have demonstrated the versatility of thread-based electroanalytical devices (μTED) constructed using a cotton thread as the solution channel and screen-printed electrodes (SPE) surface modified with carbon nanotubes (CNT) as electrochemical detectors for the amperometric determination of estriol hormone in pharmaceutical samples. The parameters involved in the amperometric detection and microflow system were studied and optimized, using the best experimental conditions (flow rate of 0.50 μL s−1, 10 mm of analytical path, 2.0 μL of volume of injection and potential of detection of 0.75 V) a linear response was observed for concentration range (LDR) of 1.0 to 1000 μmol L−1 with limits of detection (LOD) and quantification (LOQ) of 0.53 μmolL−1 and 1.77 μmolL−1, respectively, and frequency of injection of 32 per hour. The proposed methodology was applied for determination of estriol in commercial samples and results were compared with those provided by spectrophotometric method (official methodology). The obtained results are in agreement at a 95% of confidence level

Combination of electrochemical biosensor and textile threads: A microfluidic device for phenol determination in tap water

© 2017 Elsevier B.V. Microfluidic devices constructed using low cost materials presents as alternative for conventional flow analysis systems because they provide advantages as low consumption of reagents and samples, high speed of analysis, possibility of portability and the easiness of construction and maintenance. Herein, is described for the first time the use of an electrochemical biosensor for phenol detection combined with a very simple and efficient microfluidic device based on commercial textile threads. Taking advantages of capillary phenomena and gravity forces, the solution transportation is promoted without any external forces or injection pump. Screen printed electrodes were modified with carbon nanotubes/gold nanoparticles followed by covalent binding of tyrosinase. After the biosensor electrochemical characterization by cyclic voltammetry technique, the optimization of relevant parameters such as pH, potential of detection and linear range for the biosensor performance was carried out; the system was evaluated for analytical phenol detection presenting limit of detection and limit of quantification 2.94 nmol L −1 and 8.92 nmol L −1 respectively. The proposed system was applied on phenol addition and recovery studies in drinking water, obtaining recoveries rates between 90% and 110%