Phenolic acids in Irish whiskeys were determined using CE-UV with field amplified sample stacking. Length of aging and prior use of cask influenced phenolic acid profiles.

The reproducible fabrication of nanostructured 3Dimensional (3D) binary colloidal crystal (bCC) in a defined geometric space through a simple one step process is detailed. This method allows for the potential fabrication of a bCC in a sealed μchip within a defined area or channel by capillary forces, unlike other bCC formation methods such as dip-drawing, where the substrate must be submerged in a suspension to form a bCC, or bCC monolayers, which are fabricated at the water air interface. Through simple variation in volume fraction ratio (VF(S/L)) of nano-(denoted small, S) and macro-sized (denoted large, L) polystyrene (PS) spheres and diameter size ratio (D(S/L)), the manipulation of bCC structures was also achieved. Variation of nano-sized PS sphere number within the interstitial voids formed between neighbouring macro-sized spheres enabled the reproducible fabrication of LS2 and LS6 structures, which contain 1 and 3 nano-spheres respectively in each interstitial void. It must be noted that while VF(S/L) allows for control of the final LSn structure, thickness of bCC formation in this manner is independent of VFS/L.

A chemical polymerisation method for fabricating an electrochemically addressable, three dimensionally (3-D) ordered homogenous polyaniline (PANI)-based opal structure in a microfluidic channel is described.

Silver paste electrodes modified with lyotropic phases formed from dodecyl benzenesulphonic acid and KCl were used as the reductant in the determination of the hydrogen peroxide released from the enzymatic reaction of glucose oxidase with glucose and oxygen. The response of the modified electrode to hydrogen peroxide reduction (-0.1 V vs. Ag/AgCl) was shown to suffer from interference resulting from co-localization of enzyme and substrate at the electrode surface. This interference was eradicated by the introduction of a perm-selective membrane in the form of cellulose acetate. This further facilitated immobilization of the enzyme while allowing diffusion of the generated peroxide to the electrode. The resulting configuration was shown to be capable of the analytical determination of glucose.

Inverse opal monolithic flow-through structures of conducting polymer (CP) were achieved in microfluidic channels for lab-on-a-chip (LOC) applications. In order to achieve the uniformly porous monolith, polystyrene (PS) colloidal crystal (CC) templates were fabricated in microfluidic channels. Consequently, an inverse opal polyaniline (PANI) structure was achieved on-chip, through a two-step process involving the electrochemical growth of PANI and subsequent removal of the template. In this work the effect of CP electropolymerisation time on these structures is discussed. It was found that growth time is critical in achieving an ordered structure with well-defined flow-through pores. This is significant as these optimised porous structures will allow for maximising the surface area of the monolith and will also result in well-defined flow profiles through the microchannel.

In recent years, much research has focused on the development of low-cost, printed electrochemical sensor platforms for environmental monitoring and clinical diagnostics. Much effort in this area has been based on utilising the redox properties of conducting polymers, particularly polyaniline (PANI). In tackling the inherent lack of processability exhibited by these materials, several groups have examined various mass-amenable fabrication approaches to obtain suitable thin films of PANI for sensing applications. Specifically, the approaches investigated over the years include the in situ chemical synthesis of PANI, the use of sulphonated derivatives of PANI and the synthesis of aqueousbased nano-dispersions of PANI. Nano-dispersions have shown a great deal of promise for sensing applications, given that they are inkjet-printable, facilitating the patterning of conducting polymer directly to the substrate. We have shown that inkjet-printed films of PANI can be finely controlled in terms of their two-dimensional pattern, thickness, and conductivity, highlighting the level of precision achievable by inkjet printing. Utilising these nanomaterials as inkjet-printable inks opens novel, facile, and economical possibilities for conducting polymer-printed electronic applications in areas of sensing, but also many other application areas such as energy storage, displays, organic light-emitting diodes. Given that inkjet-printing is a scalable manufacturing technique, it renders possible the large-scale production of devices such as sensors for a range of applications. Several successes have emerged from our work and from the work of others in the area of applying PANI in low-cost sensor applications, which is the focus of this review.

The modification of silver screen-printed electrodes with a dodecyl benzenesulfonic acid and KCl solution was performed by inkjet printing. Scanning Electron Microscopy was performed to characterize the electrode surfaces. Electrochemical reduction of H2O2 was studied and compared to electrodes modified by dip-coating. Analytical parameters of the all-printed electrode such as LOD, sensitivity and inter-electrode reproducibility were calculated (5.8x10-6 M, 4.9x10-2 AM-1cm-2 and approx. 10%) and contrasted with other data in the literature for the measurement of H2O2. Ink jet printing led to reductions in required surface modification times and improved signal to background levels and reproducibility.

A simple and rapid HPLC assay method for the estimation of propranolol (InderalR) in human plasma was developed and validated. The method totally eliminates the extraction procedure; sample clean-up was achieved by on-line solid-phase extraction. The separation was achieved with μBondapack 10 μm C18 column (octadecylsilane, 30 cm×3.9 mm). The mobile phase consisted of a mixture of water, methanol, acetonitrile, acetic acid and triethylamine in the proportion of 160 ml: 80 ml: 70 ml: 2.5 ml: 125 μl, respectively. The pH was adjusted to 3.4 using 1 N NaOH before the addition of triethylamine. The mobile phase was filtered (0.2 μm filter) and degasified in a ultrasonic bath. The mobile phase flow rate was 0.5 ml/min. Detection was by UV detector at 291 nm and the retention time (RT) observed at around 8 minutes. The recovery of the drug from plasma was assessed by comparing the peak height of the extracted plasma samples with the peak height of authentic (un-extracted) standards which were directly injected (i.e. without column switching) into the analytical column at these concentration levels. The recovery values showed differences lower than 4.0% between the added amount and the founded amount, and were independent of the concentration. The response was linear over a range of 20-100 ng/ml with a limit of detection of 1 ng/ml and limit of quantification at 8 ng/ml plasma. This limit of quantification is adequate for clinical analysis and pharmacotherapeutic studies and comparable to those values obtained by other workers. The same method was used for the bioavailability study of propranolol formulation in healthy, human and male volunteers.

The enhanced electrocatalytic reduction of hydrogen peroxide brought about by the modification of noble metal electrode surfaces with a modification of surfactant and salt was assessed. A range of electrodes composed of Ag, Au and Pt, either as continuous metal films or as particulate metallic pastes were employed. Several surfactants (cationic, anionic and non-ionic), as well as a range of Group I metal halides with differing cations were all investigated to assess the contribution of these components to the reduction of hydrogen peroxide at −0.1V vs. Ag/AgCl. It was shown that on silver paste electrodes, all surfactant/salt combinations enhanced the observed catalysis. However, the degree to which they did this appears related to the critical micellar concentration of the surfactant, the size of the Group I metal ion and the optimum formation of lamellar structures formed by the surfactant/salt combination. Metallic electrodes showed less enhancement of catalysis over particulate paste electrodes. In addition, higher grade metallic surfaces showed poorer enhancements in catalysis which may relate to the extent of surface defects amenable to surface modification, as observed by electron microscopy. Silver paste electrodes modified with dodecylbenzene sulphonic acid/KCl exhibited a catalytic rate of 5.47×10−2AM−1cm−2, which was between 2- and 4-fold less than that observed on equivalent Pt electrodes.

A range of pathological conditions can lead to elevated blood ammonia and urea nitrogen levels. These include kidney and liver dysfunction and urea cycle defects. These conditions result in severe reduction in quality and quantity of life. Blood nitrogen levels are controlled by dialysis and monitored using invasive blood tests. Blood nitrogen levels have the potential to be monitored non-invasively in by measuring ammonia in breath. We have developed a device for monitoring human breath ammonia levels.

Polystyrene (PS) spheres are potentially useful as a reproducible, sacrificial templating material for monolith columns once they can be utilised to create a uniform microstructured packing which enables a higher monolith batch to batch reproducibility. To achieve PS spheres which can meet these requirements, their synthesis was optimised. Parameters investigated included variation of reactant concentrations, along with optimisation of reaction conditions temperature, agitation speed and nitrogen flow during aeration. Temperature and agitati on played vital roles in the size and homogeneity of the synthesised PS spheres. Temperature affected the equilibrium concentration of monomer in the aqueous phase. When reaction temperature was increased, sphere size reduced and as reaction temperature decreased sphere size increased. A similar trend was seen when agitation speed was varied. At higher agitation speed average PS sphere size decreased as the rate of polymerisation increased. At lower agitation speed the average PS sphere size increased as the rate of polymerisation decreased. Ensuring fluctuations in both temperature and agitation were kept to a minimum was key to maintaining reproducibility. Any fluctuation above ~10% in either temperature or agitation speed affected standard deviation irreversibly. The facile dissolution of the PS spheres was also investigated. If the spheres produced could not be dissolved, their use as a sacrificial templating material would not be possible. By decreasing the original concentration of cross-linker, dissolution increased dramatically

Current approaches to fabricate hierarchically porous (macroporous-mesoporous) monolithic materials for HPLC include using silica and thermally- or UV-initiated organic polymer. Silica monolith preparation is usually carried out using a sol–gel process to induce a hierarchical pore structure. Polymer monoliths, which contain primarily macropores have emerged as complimentary stationary phases to silica monoliths. It has proven difficult to date to prepare polymer monoliths in a single-step that possess a hierarchical pore structure, i.e. large through-pores, to enable flow at low back pressure, and a multiplicity of mesopores to increase surface area. 3D binary colloidal crystals may be formed by packing uniform spheres, followed by filling the interstitial space with a fluid that is subsequently converted into a solid skeleton. Upon removal of the spheres, a solid skeleton is created in the former interstitial spaces and interconnected voids where the spheres were originally located. By virtue of creating the solid skeleton, smaller pores (small macropores, mesopores, or micropores) can naturally be formed, e.g. as occurs during silica monolith fabrication. Further control of the skeleton architecture can be obtained when a secondary template is employed, e.g. ionic and nonionic surfactants, block copolymers, small colloids, etc. Micro-and nano-structuring using sacrificial templating approaches can induce both macropores and mesopores into polymer monoliths that can increase surface area by several orders of magnitude in a highly controlled fashion.

The modification of silver paste electrodes with a combination of dodecylbenzenesulfonic acid and KCl has been shown to lead to significant enhancements of the electrochemical reduction of hydrogen peroxide. The catalytic enhancement was shown to be dependent on the concentration of the surfactant/salt solution, which resulted in increases of some 80-fold in amperometric response to hydrogen peroxide at -0.1 V vs Ag/AgCl, pH 6.8 over unmodified silver paste. Physical analysis Showed modifications to both the surface morphology and chemical composition of the silver paste electrode surface. However, BET and electrochemical analysis revealed no significant change in surface area. It is suggested that the enhanced catalysis may result from the formation of stabilised surfactant/salt structures at the metal electrode surface. The electrode was also shown to be suitable for the amperometric detection of hydrogen peroxide with a limit of detection of 1.1 x 10(-6) M (S/N = 3). (C) 2011 Elsevier Ltd. All rights reserved.

Inkjet printable polyaniline-gold (PANI-Au) hybrid dispersions were synthesised using gold salt as oxidant to simultaneously induce chemical oxidative polymerisation of aniline and reduction of HAuCl4 in bulk aqueous solution. By varying the amount of HAuCl4 used for the polymerisation, the size, morphology and population of the resulting gold particles embedded within the polymer were controllable. It was shown however, that the metallic gold particles contained within the resulting dispersions did not appear to affect the bulk conductivity of PANI, but rather that by varying the amount of HAuCl4 used, both the quality and printability of the resulting PANI-Au dispersion could be affected. PANI-Au synthesised using a ratio of 1:0.25 aniline:HAuCl4 was shown to be optimum as it resulted in dispersions with high polymer conjugation lengths and doping levels, as well as high conductivity and well-defined electrochemistry. This hybrid material was shown to be highly processable, and inkjet printing of this material was demonstrated on flexible substrate which resulted in high quality, printed films.