The effect of conditioning of fused‐silica capillaries on their electrophoretic performance

Gómez, Jorge E.; Sandoval, Junior E.

doi:10.1002/elps.200700577

Cited by 30 publications

(29 citation statements)

References 28 publications

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“…Prior to modification, fused-silica capillaries (typically, a 6.0-m length) and wafers were conditioned by etching with NaOH followed by leaching with HCl, according to procedures described elsewhere (27). Porous silica particles did not undergo any conditioning.…”

Section: Methodsmentioning

confidence: 99%

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Navarro

Gómez

Espinal

et al. 2016

Analytica Chimica Acta

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In the present study, porous silica particles as well as impervious fused-silica wafers and capillary tubes were modified with hydrophilic polymers (hydroxylated polyacrylamides and polyacrylates), using a surface-confined grafting procedure based on atom transfer radical polymerization (ATRP) which was also surface-initiated from α-bromoisobutyryl groups. Initiator immobilization was achieved by hydrosilylation of allyl alcohol on hydride silica followed by esterification of the resulting propanol-bonded surface with α-bromoisobutyryl bromide. Elemental analysis, IR and NMR spectroscopies on silica micro-particles, atomic force microscopy, ellipsometry and profilometry on fused-silica wafers, as well as CE on fused-silica tubes were used to characterize the chemically modified silica substrate at different stages. We studied the effect of monomer concentration as well as cross-linker on the ability of the polymer film to reduce electroosmosis and to prevent protein adsorption (i. e., its non-fouling capabilities) and found that the former was rather insensitive to both parameters. Surface deactivation towards adsorption was somewhat more susceptible to monomer concentration and appeared also to be favored by a low concentration of the cross-linker. The results show that hydrophilic polyacrylamide and polyacrylate coatings of controlled thickness can be prepared by ATRP under very mild polymerization conditions (aqueous solvent, room temperature and short reaction times) and that the coated capillary tubes exhibit high efficiencies for protein separations (0.3–0.6 million theoretical plates per meter) as well as long-term hydrolytic stability under the inherently harsh conditions of capillary isoelectric focusing. Additionally, there was no adsorption of lysozyme on the coated surface as indicated by a complete recovery of the basic enzyme. Furthermore, since polymerization is confined to the inner capillary surface, simple precautions (e.g., solution filtration) during the surface modification process are sufficient to prevent capillary clogging.

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Section: Methodsmentioning

confidence: 99%

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Navarro

Gómez

Espinal

et al. 2016

Analytica Chimica Acta

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“…In CE practice, conditioning of the capillary tube with strong base, acid, or both in sequence has been recognized as essential to obtain reasonable precision in electroosmotic flow (EOF) and, consequently, in the migration times of analytes [20]. Conditioning of fused-silica capillaries in this work was optimized by monitoring repeatability of migration time of EOF, as well as migration time and peak area of the analytes.…”

Section: Capillary Rinse Between Injectionsmentioning

confidence: 99%

Determination of formaldehyde in aquatic products by micellar electrokinetic capillary chromatography with 2,4-dinitrophenylhydrazine derivatization

Xu¹,

Gai²,

Mu³

et al. 2012

Acta Chromatographica

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Summary. Formaldehyde in aquatic products was determined by micellar electrokinetic capillary chromatography (MEKC) after derivatization with 2,4-dinitrophenylhydrazine. Separation was carried out at 25 °C and 25 kV, using a fused silica capillary (75 μm internal diameter; 50.5 cm effective length) and an ultraviolet detector set at 360 nm. The optimal background electrolyte was 20 mM sodium tetraborate and 20 mM sodium dodecyl sulfate at pH 9.0 with 3 s hydrodynamic injection at 30 mbar. Electrophoretic analysis took approximately 6.5 min. The correlation coefficient of the calibration curve was 0.999 over the concentration range 2.0-100.0 mg L −1 , and the LOD and LOQ values were 0.57 and 1.89 μg mL −1 , respectively. The recoveries were from 83.7% to 97.2% with steam distillation as the sample pretreatment method.

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“…In CE practice, the different approaches for capillary conditioning have great influence on the electrophoretic performance [37]. To obtain the reproducible results, two methods for capillary conditioning were used in the process of experiments.…”

Section: Effect Of Different Capillary Conditioningmentioning

confidence: 99%

Determination of levofloxacin and norfloxacin by capillary electrophoresis with electrochemiluminescence detection and applications in human urine

et al. 2008

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A novel method for the determination of norfloxacin (NOR) and levofloxacin (LVX) was developed by CE separation and electrochemiluminesence detection (ECL). The methods for capillary conditioning and the effect of solvent type were studied. Parameters affecting the CE and ECL were also investigated. Under the optimum conditions, the two analytes were well separated within 9 min. The LODs (S/N = 3) in standard solution are 4.8 x 10(-7) mol/L for NOR and 6.4 x 10(-7) mol/L for LVX, respectively. The precisions of intraday and interday are less than 4.2 and 8.1%, respectively. The LOQs (S/N = 10) in real human urine samples are 1.2 x 10(-6) mol/L for NOR and 1.4 x 10(-6) mol/L for LVX, respectively. The applicability of the proposed method was illustrated in the determination of NOR and LVX in human urine samples and the monitoring of pharmacokinetics for NOR. The recoveries of NOR and LVX at different levels in human urine samples were between 84.3 and 92.3%.

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The effect of conditioning of fused‐silica capillaries on their electrophoretic performance

Cited by 30 publications

References 28 publications

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Determination of formaldehyde in aquatic products by micellar electrokinetic capillary chromatography with 2,4-dinitrophenylhydrazine derivatization

Determination of levofloxacin and norfloxacin by capillary electrophoresis with electrochemiluminescence detection and applications in human urine

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