Development of fast ion chromatography

Fast ion chromatography has been applied to short (3 cm) silica based ODS columns with a view to achieving rapid determinations of selected inorganic anions. The use of smaller stationary phase particle sizes (3 |im) allowed higher flow rates (2.0 - 2.5 ml/min) to be used while maintaining chromatographic efficiency due to the favorable Van Deemter curves obtained as particle size decreases. Using ioninteraction chromatography and direct UV detection, eight anions were separated in under four minutes with the first five anions separated in < 50 seconds; this separation was subsequently applied to the rapid analysis of nitrite and nitrate in tap water. With the addition of a peristaltic pump and in-line filter, up to 60 analyses per hour could be carried out unattended using an on-line system, which matches the analysis rate possible with traditional FIA based methods. This mobile phase was further modified such that nitrate, nitrite and thiocyanate could be rapidly determined in urine samples as a means to quantitatively evaluate smoking behavior. Subsequently, the same column was permanently coated using didodecyldimethylammonium bromide (DDAB) and anion exchange chromatography used for the isocratic separation of nine common anions in 160 seconds, with the first seven anions, including phosphate, chloride and sulphate, separated within only 65 seconds using a simple phthalate eluent. The high capacity, highly hydrophobic ion exchange coating demonstrated excellent stability over time, even at elevated temperatures (45 °C). The developed chromatography was successfully applied to the rapid analysis of river water, tap water and relatively high ionic strength seawater samples with minimal sample preparation required. Multi-valent eluents were briefly applied to this column with a view to achieving faster separations, with further studies also involved the use of dipicolinic acid eluents, which allowed the simultaneous separation of chloride, sulphate, nitrate, carbonate, magnesium and calcium, in less than 180 seconds. Short monolithic silica ODS columns were used with a tetrabutylammoniumphthalate eluent and direct conductivity detection for the rapid analysis of six common inorganic anions in < 60 seconds. Van deemter curves for this monolithic column showed that considerably higher flow rates could be used without adversely affecting efficiency relative to 3 p,m particulate columns due to the improved permeability of these phases. Finally, two short Cis monoliths were coated with DDAB and DOSS and individually used to separate eight anions in 100 seconds and five cations in 100 seconds using a common phthalate/ethylenediamine eluent. By subsequently coupling the columns in parallel, the with the eluent delivered using a flow splitter from a single isocratic pump, the simultaneous analysis of anions and cations was also possible, based on a single conductivity detector

AuNP-Agglomerated monoliths in pipette tips for lectin affinity extraction of glycoproteins

• To in situ fabricate ethylene dimethacrylate porous polymer monoliths within the confines of a commercial 20 μL polypropylene pipette tips. • To enhance the monolith surface area by immobilising AuNPs and then functionalise the AuNPs with ECL lectin for selective extraction of galactosylated proteins from complex media

Development and characterisation of switchable polyaniline-functionalised flow-through capillary monoliths

Polymer monoliths were prepared in capillary format (250 mm i.d.) and used as solid supports for the immobilisation of the conducting polymer polyaniline (PANI). The immobilisation of PANI was confirmed on the large macro-porous structure of a polystyrene–divinylbenzene (PS-co-DVB) monolith. The surface coverage of polyaniline was characterised by field emission scanning electron microscopy (FESEM) and by capacitively coupled contactless conductivity detection (C4D), which was operated in scanning mode to non-invasively visualise the axial distribution of the immobilised PANI and to provide information on its doping state. To further demonstrate the successful functionalisation of the monoliths, the PANI-functionalised monoliths were demonstrated as switchable, weak anion-exchange stationary phases as confirmed by studying the retention of iodide using a perchlorate eluent

Versatile capillary column temperature control using a thermoelectric array based platform

A new direct contact platform for capillary column precise temperature control based upon the use of individually controlled sequentially aligned Peltier thermoelectric units is presented. The platform provides rapid temperature control for capillary and microbore liquid chromatography columns and allows simultaneous temporal and spatial temperature programming. The operating temperature range of the platform was between 15 and 200 0C for each of 10 aligned Peltier units, with a ramp rate of approximately 400 0C/min. The system was evaluated for a number of nonstandard capillary based applications, such as the direct application of temperature gradients with both linear and nonlinear profiles, including both static column temperature gradients and temporal temperature gradients, and the formation of in-capillary monolithic stationary phases with gradient polymerization through precise temperature control

Framing headship:A demand-side analysis of how the headteacher role is articulated in job descriptions

The majority of studies into recruitment to the headship role have focused on supply-side dynamics and teachers’ own accounts of the factors that (dis)incentivize them from aspiring or progressing to headship. Significantly less work has been done in analyzing demand-side factors. This paper addresses the gap by presenting findings from a mixed-methods analysis of headteacher job descriptions (n = 67) published in a complete school year within Wales – one of the UK’s devolved education systems. A discourse analysis was conducted, based on organizational and occupational conceptions of professional work, which informed a subsequent content analysis of the job descriptions. Our findings identified a dominance of articulations that privileged organizationally-orientated understandings of headship and evidence of a lack of contextualization and agency by stakeholders responsible for recruitment. Such ‘demand-side’ analysis offers scope for examining and understanding the way in which headship is framed and aligns with policy within a variety of international educational contexts and jurisdictions