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M ID Fused Silica Capillaries (m + id_fused_silica_capillary)
Selected AbstractsMonolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Andreas Greiderer Abstract Monolithic poly(1,2-bis(p -vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p -vinylphenyl)ethane in the presence of inert diluents (porogens) and ,,,,-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 ,m ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5,400 nm and flow-channels in the ,m range. N2 -adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (,20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p -vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for ,-HPLC towards a huge range of analytes of different chemistries and molecular sizes. [source] Highly cross-linked polymeric capillary monoliths for the separation of low, medium, and high molecular weight analytesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Said H. Lubbad Abstract Highly rigid capillary monoliths with low swelling propensity were prepared within the confines of 200 ,m ID fused silica capillaries via thermally induced free radical polymerization of tetrakis(4-vinylbenzyl)silane (TVBS) in the presence of 1-dodecanol and toluene. ,,,,-Azobisisobutyronitrile (AIBN) was used as initiator. The resulting monoliths were optimized for the separation of low, medium, and high molecular weight analytes. The microstructure and porosity of the monoliths prepared were studied by SEM and inverse size-exclusion chromatography (ISEC). The porosity of the monolithic supports was tuned by varying the amount of initiator (i. e. AIBN) between 0.5 and 2 wt%. All monoliths were tested for a series of low molecular weight compounds including alkylbenzenes, amines, carboxylic acids, phenols, carbonyl compounds, and ,-blockers, as well as for the separation of medium molecular weight analytes such as peptides and high-molecular weight analytes such as proteins. Due to the microporous structure, the novel monoliths displayed high efficiency and performance particularly in the separation of low molecular weight analytes. Relevant chromatographic parameters including permeability, swelling propensity, and height equivalents to theoretical plates were determined. [source] Design and characterization of a prototype enzyme microreactor: Quantification of immobilized transketolase kineticsBIOTECHNOLOGY PROGRESS, Issue 1 2010S. Matosevic Abstract In this work, we describe the design of an immobilized enzyme microreactor (IEMR) for use in transketolase (TK) bioconversion process characterization. The prototype microreactor is based on a 200-,m ID fused silica capillary for quantitative kinetic analysis. The concept is based on the reversible immobilization of His6 -tagged enzymes via Ni-NTA linkage to surface derivatized silica. For the initial microreactor design, the mode of operation is a stop-flow analysis which promotes higher degrees of conversion. Kinetics for the immobilized TK-catalysed synthesis of L -erythrulose from substrates glycolaldehyde (GA) and hydroxypyruvate (HPA) were evaluated based on a Michaelis,Menten model. Results show that the TK kinetic parameters in the IEMR (Vmax(app) = 0.1 ± 0.02 mmol min,1, Km(app) = 26 ± 4 mM) are comparable with those measured in free solution. Furthermore, the kcat for the microreactor of 4.1 × 105 s,1 was close to the value for the bioconversion in free solution. This is attributed to the controlled orientation and monolayer surface coverage of the His6 -immobilized TK. Furthermore, we show quantitative elution of the immobilized TK and the regeneration and reuse of the derivatized capillary over five cycles. The ability to quantify kinetic parameters of engineered enzymes at this scale has benefits for the rapid and parallel evaluation of evolved enzyme libraries for synthetic biology applications and for the generation of kinetic models to aid bioconversion process design and bioreactor selection as a more efficient alternative to previously established microwell-based systems for TK bioprocess characterization. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Field-amplified sample injection-micellar electrokinetic capillary chromatography for the analysis of bisphenol A, bisphenol F, and their diglycidyl ethers and derivatives in canned soft drinksELECTROPHORESIS, Issue 9 2010Héctor Gallart-Ayala Abstract Conditions were established for the separation and analysis of bisphenol A, bisphenol F, and their diglycidyl ethers by micellar electrokinetic capillary chromatography (MECC). Good resolution was obtained for all compounds, although in order to achieve the separation of ortho,ortho, ortho,para, and para,para isomers of bisphenol F diglycidyl ether (BFDGE), BFDGE·2H2O and BFDGE·2HCl, it was necessary to use a 25,,m id fused silica capillary. To increase sensitivity, a field-amplified sample injection (FASI)-MECC method was developed using 10,mM SDS solution as injection matrix and a 75,,m id fused silica capillary. Instrumental quality parameters such as LODs (<55,,g/L with standards), linearity (r2>0.999), and run-to-run and day-to-day precisions (RSD values lower than 12.5%) were determined. Finally, the suitability of the FASI-MECC method for the analysis of bisphenol A, bisphenol F, and their diglycidyl ethers in canned soft drinks was evaluated. Quantitation was performed by matrix-matched calibration using a plastic-bottled isotonic drink as matrix. The results showed that FASI-MECC is an economic method for the screening and quantitation of these kinds of compounds in soft drink beverages, with no loss of reproducibility, and effective at concentrations lower than the specific migration level values established by the European Union. [source] | ||||||||||