Quality control of gasohol using a micro-unit for membraneless gas diffusion

This work describes the development of a new spectrophotometric flow technique suitable for monitoring of ethanol content in gasohol fuel. Membraneless gas-diffusion (MBL-GD) was applied with one-step aqueous extraction of gasohol (1:2 gasohol/water). Segments of aqueous extract and color developing reagent were allowed to flow into two separate channels in the MBL-GD device. Inside the device, ethanol vapor can diffuse across a small headspace between the two channels (donor and acceptor). Introduction of an air-segment behind the zone of acceptor reagent to stop dispersion of the colored zone greatly improves the rapidity of analysis using this MBL-GD technique. Two methods were developed for quality control of gasohol by measuring ethanol content. Method I is suitable for direct calibration of E5 and E10. Method II is recommended for E20. These methods have high accuracy with good precision (% RSD: 1 to 4.9, n&#8201;=&#8201;45) and have a sample throughput of 26 samples per hour. E10 samples were compared with analysis using a standard GC method. </p

Utilising bio-based plasticiser castor oil and recycled PLA for the production of conductive additive manufacturing feedstock and detection of bisphenol A

The production of electrically conductive additive manufacturing feedstocks from recycled poly(lactic acid) (rPLA), carbon black (CB), and bio-based plasticiser castor oil is reported herein. The filament was used to print additively manufactured electrodes (AMEs), which were electrochemically benchmarked against geometrically identical AMEs printed from a commercially available conductive filament. The castor oil/rPLA AMEs produced an enhanced heterogeneous electrochemical rate constant of (1.71 ± 0.22) × 10−3 cm s−1 compared to (0.30 ± 0.03) × 10−3 cm s−1 for the commercial AME, highlighting the improved performance of this filament for the production of working electrodes. A bespoke electroanalytical cell was designed and utilised to detect bisphenol A (BPA). The AMEs made from the castor oil/rPLA gave an enhanced electroanalytical performance compared to the commercial filament, producing a sensitivity of 0.59 μA μM−1, a LOD of 0.10 μM and LOQ of 0.34 μM. This system was then successfully applied to detect BPA in spiked bottled and tap water samples, producing recoveries between 89-104%. This work shows how the production of conductive filaments may be done more sustainably while improving performance

MIP-based electrochemical protein profiling

We present the development of an electrochemical biosensor based on modified glassy carbon (GC) electrodes using hydrogel-based molecularly imprinted polymers (MIPs) has been fabricated for protein detection. The coupling of pattern recognition techniques via principal component analysis (PCA) has resulted in unique protein fingerprints for corresponding protein templates, allowing for MIP-based protein profiling. Polyacrylamide MIPs for memory imprinting of bovine haemoglobin (BHb), equine myoglobin (EMb), cytochrome C (Cyt C), and bovine serum albumin (BSA), alongside a non-imprinted polymer (NIP) control, were spectrophotometrically, and electrochemically characterised using modified GC electrodes. Rebinding capacities (Q) were revealed to be higher for larger proteins (BHb and BSA, Q ≈ 4.5) while (EMb and Cyt C, Q ≈ 2.5). Electrochemical results show that due to the selective nature of MIPs, protein arrival at the electrode via diffusion is delayed, in comparison to a NIP, by attractive selective interactions with exposed MIP cavities. However, at lower concentrations such discriminations are difficult due to low levels of MIP rebinding. PCA loading plots revealed 5 variables responsible for the separation of the proteins; E, I, E, I, ΔI . Statistical symmetric measures of agreement using Cohen's kappa coefficient (κ) were revealed to be 63% for bare GC, 96% for NIP and 100% for MIP. Therefore, our results show that with the use of PCA such discriminations are achievable, also with the advantage of faster detection rates. The possibilities for this MIP technology once fully developed are vast, including uses in bio-sample clean-up or selective extraction, replacement of biological antibodies in immunoassays, as well as biosensors for medicine, food and the environment. © 2014 Elsevier B.V