Isoelectric Focusing Sample Injection for Capillary Zone Electrophoresis in a Fused Silica Capillary

Zhang, Luo-Hong; Zhang, Chengjie; Wu, Xing-Zheng

doi:10.2116/analsci.22.1039

Cited by 10 publications

(8 citation statements)

References 20 publications

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“…The MNB obtained an over 100-fold SE. In 2006, Zhang et al 106 invented IEF sample injection for the stacking of lysozyme and ribonuclease A in CE. A higher than 100-fold SE can be easily achieved for the two proteins.…”

Section: Sample Stackingmentioning

confidence: 99%

Review on the theory of moving reaction boundary, electromigration reaction methods and applications in isoelectric focusing and sample pre-concentration

Cao

Fan

Zhang

2008

Analyst

157

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Since 1970, a series of systematic investigations have been performed on three modes of moving reaction boundaries (MRBs), viz. moving precipitate boundary (MPB), moving neutralization boundary (MNB) and moving chelation boundary (MCB). So far, there has not been any review on them. Herein, we firstly review the MPB with respect to its velocity, product concentration, elution displacement, stacking effect, separation effect, judgment expressions and related procedures. We then make a review on the MNB about its theory, demonstration, improvement, and uses in isoelectric focusing (IEF), sample stacking, MNB-based stacking mechanisms and relevant computer simulations. We further give a review on the MCB regarding the relevant theory, verifications, and applications in EDTA-based sweeping and computer simulation. Finally, we give an outlook on the MRB study. More than 150 references are cited.

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Section: Sample Stackingmentioning

confidence: 99%

Review on the theory of moving reaction boundary, electromigration reaction methods and applications in isoelectric focusing and sample pre-concentration

Cao

Fan

Zhang

2008

Analyst

157

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“…Sample cleanup and preconcentration are mainly based on the use of electrophoretic preconcentration, porous membrane, and chemical adsorption. In electrophoretic preconcentration, sample stacking, − isotachophoresis, sweeping techniques, , pH junction techniques, nonuniform capillary modulation, and capillary isoelectric focusing , are the typical examples of this type. In the porous membrane-based type, − a local porous section or a porous membrane was made near or at the inlet end of the capillary for sample preconcentration.…”

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confidence: 99%

Capillary Electrophoresis with In-Capillary Solid-Phase Extraction Sample Cleanup

Zhang

2007

Anal. Chem.

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An in-capillary, solid-phase extraction (SPE)-capillary electrophoresis (CE) method, with not only high preconcentration factor but also no adsorption on the inner capillary wall of absorbing species in real complex samples, has been developed with a hole-opened capillary. The SPE sorbents approximately 3 mm in length was packed in the inlet end of the capillary. A hole approximately 30 microm in diameter was opened after the sorbents on the capillary. Sample solutions were loaded from the inlet end, and the sample wastes flowed out from the hole. After a certain time of the sample loading, a 1.5-mm-long methanol plug was introduced from the inlet end and forced to pass by the sorbents and the hole. Then, a separation voltage was applied between the hole and the outlet end of the capillary to carry out normal CE. When the sample loading time was 120 min, CE peak heights of the 2,4-dichlorophenol and 2,4,5-trichlorophenol were proportional to their concentration in a range of 0.08-5 ng/mL, and their detection limits were 25 and 17 pg/mL, respectively. A 16,000-fold sensitivity enhancement was obtained for CE of the chlorophenols with only a little decrease in CE separation efficiency. It was also demonstrated with the mixture of the chlorophenols and a surfactant cetyltrimethylammonium bromide that the present method could eliminate the adsorption problem of absorbing species on the inner wall during sample loading. Furthermore, the SPE-CE was directly applied to determination of chlorophenols on the level of 0.02 ppb in downstream water of a river, and the results agreed well with those obtained with off-line SPE-HPLC experiments.

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“…Thus, there is a flux of OH – ions from the cathode and a flux of H + ions from the ground toward the center of the syringe barrel. When and where these two fluxes meet, a NRB is formed between acidic and basic solutions in the syringe barrel, − ,− allowing amphoteric molecules with pI values within the NRB pH gap to be focused as indicated in Figure . The span of the pH gap could be reduced by changing the flux of the solvolytic ions to allow the separation of a mixture of proteins, but this would require a more sophisticated system/platform than what is presented here.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the focusing dynamics using a pH boundary was investigated via high-resolution computer simulation studying the stacking of weak bases . The formation of the NRB was utilized for the injection of focused proteins in capillary electrophoresis, , as well as being applied for preconcentration and purification of proteins prior to offline analysis by MALDI-TOF MS. , …”

mentioning

confidence: 99%

“…24 Additionally, the focusing dynamics using a pH boundary was investigated via high-resolution computer simulation studying the stacking of weak bases. 25 The formation of the NRB was utilized for the injection of focused proteins in capillary electrophoresis, 26,27 as well as being applied for preconcentration and purification of proteins prior to offline analysis by MALDI-TOF MS. 28,29 Here, we present the first implementation of an electrokinetic technique within a syringethe electroseparation syringeexploiting the embedded stainless steel syringe needle and plunger as electrodes. Following the rich history of CAF-IEF, the electrolysis of water at the needle and plunger was used to induce a NRB to focus amphoteric molecules, such as proteins, peptides, and amino acids.…”

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confidence: 99%

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In-Syringe Electrokinetic Ampholytes Focusing Coupled with Electrospray Ionization Mass Spectrometry

et al. 2019

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A 25 μL analytical glass syringe has been used for isoelectric focusing (IEF) utilizing the stainless-steel needle and plunger as electrodes. The generation of protons and hydroxyl ions at the electrodes facilitated a neutralization reaction boundary (NRB) mechanism to focus different amphoteric compounds, such as hemoglobin, bovine serum albumin, R-phycoerythrin, and histidine, within minutes. After optimization of different experimental parameters affecting the IEF process and the coupling of the IEF syringe with electrospray ionization mass spectrometry (ESI-MS), a BGE composed of NH4Ac, 1.0 mM, pH 4.0, in 70.0% (v/v) acetonitrile was used for the IEF of histidine. A voltage of −200 V was applied for 5.0 min to accomplish the IEF and increased to −400 V during the infusion to ESI-MS at a flow rate of 4.0 μL/min. The coaxial sheath liquid consisting of 0.2% (v/v) formic acid was added at 4.0 μL/min. The detection limit was found to be 2.2 μg/mL and a nonlinear quadratic fit calibration curve was constructed for histidine over the range of 4.0–64.0 μg/mL with a correlation coefficient (r) = 0.9998. The determination of histidine in spiked urine samples as relevant for the diagnosis of histidinemia was demonstrated by the IEF syringe-ESI-MS system with accuracy from 88.25% to 102.16% and a relative standard deviation less than 11%.

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Isoelectric Focusing Sample Injection for Capillary Zone Electrophoresis in a Fused Silica Capillary

Cited by 10 publications

References 20 publications

Review on the theory of moving reaction boundary, electromigration reaction methods and applications in isoelectric focusing and sample pre-concentration

Review on the theory of moving reaction boundary, electromigration reaction methods and applications in isoelectric focusing and sample pre-concentration

Capillary Electrophoresis with In-Capillary Solid-Phase Extraction Sample Cleanup

In-Syringe Electrokinetic Ampholytes Focusing Coupled with Electrospray Ionization Mass Spectrometry

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