Synthetic micro-diamond-polydimethylsiloxane (PDMS) composite microfluidic chips and thin films w... more Synthetic micro-diamond-polydimethylsiloxane (PDMS) composite microfluidic chips and thin films were produced using indirect 3D printing and spin coating fabrication techniques. Microfluidic chips containing up to 60 wt% micro-diamond were successfully cast and bonded. Physicochemical properties, including the dispersion pattern, hydrophobicity, chemical structure, elasticity and thermal characteristics of both chip and films were investigated. Scanning electron microscopy indicated that the micro-diamond particles were embedded and interconnected within the bulk material of the cast microfluidic chip, whereas in the case of thin films their increased presence at the polymer surface resulted in a reduced hydrophobicity of the composite. The elastic modulus increased from 1.28 for a PDMS control, to 4.42 MPa for the 60 wt% composite, along with a three-fold increase in thermal conductivity, from 0.15 to 0.45 W mK. Within the fluidic chips, micro-diamond incorporation enhanced heat di...
In this work for the first time a sub-250 nm light-emitting diode (LED) is investigated as a ligh... more In this work for the first time a sub-250 nm light-emitting diode (LED) is investigated as a light source for optical detection in chemical analysis. A 235 nm deep UV-LED is employed within an on-capillary photometric detector and applied in capillary ion-exchange chromatography (IEC) to the detection of common UV absorbing anions, here iodide, nitrate and nitrite. This investigation focused on fundamental properties of UV-LEDs, in particular emission spectra, radiometric power, effective heat dissipation with a passive heat sink, and energy conversion. The detection showed excellent linearity with stray light down to 0.6%, and effective pathlength at 92% of the used capillary inner diameter. The analytical performance parameters were demonstrated by detection of chromatographic separation of iodide in simulated seawater, showing limit of detection (LOD) of 1.30 µM, linear range 7.9 to 3,937 µmol L-1, and reproducibility as relative standard deviation (RSD) of peak height 0.6%, and ...
Danilevics Ugis and Nesterenko Ekaterina and Thompson Roisin and Clarke Paul and O Connor Brendan and Paull Brett Gold Nano Particle Modified Silica Monolithic Micro Columns For Selected Chromatographic and Biological Applications in Analytical Sciences in Ireland 10 Nov 2011 Ucc Cork Ireland, Nov 10, 2011
The addition of detonation nanodiamond to carbon monolithic composites has improved graphitic nat... more The addition of detonation nanodiamond to carbon monolithic composites has improved graphitic nature, pore volume, surface area and thermal conductivity.
A new high performance chelation ion chromatography method for the simultaneous determination of ... more A new high performance chelation ion chromatography method for the simultaneous determination of trace magnesium and strontium in various calcium carbonate samples was developed.
A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and ... more A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and 10 mum, were produced using a silica particle template method. The rods were characterised using SEM and energy-dispersive X-ray spectroscopy, BET surface area and porous structure analysis, dilatometry and thermal gravimetry. SEM evaluation of the carbon monolithic structures revealed an interconnected rigid bimodal porous structure and energy-dispersive X-ray spectroscopy analysis verified the quantitative removal of the embedded silica beads. The specific surface areas of the 1, 2, 5 and 10 mum rods were 178, 154, 84 and 125 m(2)/g after pyrolysis and silica removal, respectively. Shrinkage of the monolithic rods during pyrolysis is proportional to the particle size of the silica used and ranged from 9 to 12%. Mercury porosimetry showed a narrow distribution of pore sizes, with an average of approximately 700 nm for the 1 mum carbon monolith. The suitability of bare and surface oxidised PCM rods for the use as a stationary phase for reversed and normal phase LC was explored. The additional modification of PCM rods with gold micro-particles followed by 6-mercaptohexanoic acid was performed and ion-exchange properties were evaluated.
Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine r... more Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine ratio in complex defined media feedstock using monolithic reversed-phase liquid chromatography (RPLC) and RPLC-MS are presented. Cysteine is pre-derivatised with purified 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) and separated from other derivatisation products on a narrow-bore 50mmx2mm I.D. monolithic C(18) column with UV detection at 355nm. For reversed-phase LC (RPLC) the separation is carried out isocratically using a mobile phase of 50mM trichloroacetic acid (TCA) adjusted to pH 2.5 with lithium hydroxide (LiOH) and acetonitrile (83:14) pumped at 1.5mL/min with an elevated column temperature. For RPLC-MS an ammonium acetate and acetonitrile gradient method was developed with a reduced flow rate of 0.3mL/min. The treatment of the samples consisted of dividing them into two aliquots, the first aliquot is analysed for cysteine and the second aliquot is analysed for cystine after its quantitative reduction to cysteine using tris(2-carboxyethyl)phosphine (TCEP). Both methods are linear, with R(2)>0.999 for 0.25-500microM for cysteine and 0.25-250microM for cystine using the LC-UV method, sensitive, with detection limit of 36nM for cysteine, and precise, with < or =1.1% RSD for both retention time and peak area (n=6). Samples (n=31) of an industry standard and supplied chemically defined media feedstock were analysed, finding cysteine ranging from 1.56 to 2.26microg/mL and cystine from 1062.02 to 1348.13microg/mL.
Walsh, Zarah and Heger , Dominik and Abele, Silvija and Klán, Petr and Paull, Brett and Levkin, P... more Walsh, Zarah and Heger , Dominik and Abele, Silvija and Klán, Petr and Paull, Brett and Levkin, Pavel and Svec, Frantisek and Macka, Mirek (2009) Use of light emitting diodes in the visible region to initiate polymerisation leading to monolithic stationary phases. In: ISCCE 2009 - 33rd International Symposium on Capillary Chromatography and Electrophoresis, 18-21 May 2009, Portland, OR, USA. ... DORAS is managed by DCU Library and powered by EPrints 3 which is developed by the School of Electronics and Computer Science at the University ...
Synthetic micro-diamond-polydimethylsiloxane (PDMS) composite microfluidic chips and thin films w... more Synthetic micro-diamond-polydimethylsiloxane (PDMS) composite microfluidic chips and thin films were produced using indirect 3D printing and spin coating fabrication techniques. Microfluidic chips containing up to 60 wt% micro-diamond were successfully cast and bonded. Physicochemical properties, including the dispersion pattern, hydrophobicity, chemical structure, elasticity and thermal characteristics of both chip and films were investigated. Scanning electron microscopy indicated that the micro-diamond particles were embedded and interconnected within the bulk material of the cast microfluidic chip, whereas in the case of thin films their increased presence at the polymer surface resulted in a reduced hydrophobicity of the composite. The elastic modulus increased from 1.28 for a PDMS control, to 4.42 MPa for the 60 wt% composite, along with a three-fold increase in thermal conductivity, from 0.15 to 0.45 W mK. Within the fluidic chips, micro-diamond incorporation enhanced heat di...
In this work for the first time a sub-250 nm light-emitting diode (LED) is investigated as a ligh... more In this work for the first time a sub-250 nm light-emitting diode (LED) is investigated as a light source for optical detection in chemical analysis. A 235 nm deep UV-LED is employed within an on-capillary photometric detector and applied in capillary ion-exchange chromatography (IEC) to the detection of common UV absorbing anions, here iodide, nitrate and nitrite. This investigation focused on fundamental properties of UV-LEDs, in particular emission spectra, radiometric power, effective heat dissipation with a passive heat sink, and energy conversion. The detection showed excellent linearity with stray light down to 0.6%, and effective pathlength at 92% of the used capillary inner diameter. The analytical performance parameters were demonstrated by detection of chromatographic separation of iodide in simulated seawater, showing limit of detection (LOD) of 1.30 µM, linear range 7.9 to 3,937 µmol L-1, and reproducibility as relative standard deviation (RSD) of peak height 0.6%, and ...
Danilevics Ugis and Nesterenko Ekaterina and Thompson Roisin and Clarke Paul and O Connor Brendan and Paull Brett Gold Nano Particle Modified Silica Monolithic Micro Columns For Selected Chromatographic and Biological Applications in Analytical Sciences in Ireland 10 Nov 2011 Ucc Cork Ireland, Nov 10, 2011
The addition of detonation nanodiamond to carbon monolithic composites has improved graphitic nat... more The addition of detonation nanodiamond to carbon monolithic composites has improved graphitic nature, pore volume, surface area and thermal conductivity.
A new high performance chelation ion chromatography method for the simultaneous determination of ... more A new high performance chelation ion chromatography method for the simultaneous determination of trace magnesium and strontium in various calcium carbonate samples was developed.
A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and ... more A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and 10 mum, were produced using a silica particle template method. The rods were characterised using SEM and energy-dispersive X-ray spectroscopy, BET surface area and porous structure analysis, dilatometry and thermal gravimetry. SEM evaluation of the carbon monolithic structures revealed an interconnected rigid bimodal porous structure and energy-dispersive X-ray spectroscopy analysis verified the quantitative removal of the embedded silica beads. The specific surface areas of the 1, 2, 5 and 10 mum rods were 178, 154, 84 and 125 m(2)/g after pyrolysis and silica removal, respectively. Shrinkage of the monolithic rods during pyrolysis is proportional to the particle size of the silica used and ranged from 9 to 12%. Mercury porosimetry showed a narrow distribution of pore sizes, with an average of approximately 700 nm for the 1 mum carbon monolith. The suitability of bare and surface oxidised PCM rods for the use as a stationary phase for reversed and normal phase LC was explored. The additional modification of PCM rods with gold micro-particles followed by 6-mercaptohexanoic acid was performed and ion-exchange properties were evaluated.
Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine r... more Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine ratio in complex defined media feedstock using monolithic reversed-phase liquid chromatography (RPLC) and RPLC-MS are presented. Cysteine is pre-derivatised with purified 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) and separated from other derivatisation products on a narrow-bore 50mmx2mm I.D. monolithic C(18) column with UV detection at 355nm. For reversed-phase LC (RPLC) the separation is carried out isocratically using a mobile phase of 50mM trichloroacetic acid (TCA) adjusted to pH 2.5 with lithium hydroxide (LiOH) and acetonitrile (83:14) pumped at 1.5mL/min with an elevated column temperature. For RPLC-MS an ammonium acetate and acetonitrile gradient method was developed with a reduced flow rate of 0.3mL/min. The treatment of the samples consisted of dividing them into two aliquots, the first aliquot is analysed for cysteine and the second aliquot is analysed for cystine after its quantitative reduction to cysteine using tris(2-carboxyethyl)phosphine (TCEP). Both methods are linear, with R(2)>0.999 for 0.25-500microM for cysteine and 0.25-250microM for cystine using the LC-UV method, sensitive, with detection limit of 36nM for cysteine, and precise, with < or =1.1% RSD for both retention time and peak area (n=6). Samples (n=31) of an industry standard and supplied chemically defined media feedstock were analysed, finding cysteine ranging from 1.56 to 2.26microg/mL and cystine from 1062.02 to 1348.13microg/mL.
Walsh, Zarah and Heger , Dominik and Abele, Silvija and Klán, Petr and Paull, Brett and Levkin, P... more Walsh, Zarah and Heger , Dominik and Abele, Silvija and Klán, Petr and Paull, Brett and Levkin, Pavel and Svec, Frantisek and Macka, Mirek (2009) Use of light emitting diodes in the visible region to initiate polymerisation leading to monolithic stationary phases. In: ISCCE 2009 - 33rd International Symposium on Capillary Chromatography and Electrophoresis, 18-21 May 2009, Portland, OR, USA. ... DORAS is managed by DCU Library and powered by EPrints 3 which is developed by the School of Electronics and Computer Science at the University ...
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