Control of electroosmotic flow in nonaqueous capillary electrophoresis by polymer capillary coatings

Steiner, Frank; Hassel, Marc

doi:10.1002/elps.200390050

Cited by 39 publications

(34 citation statements)

References 36 publications

(31 reference statements)

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“…Interestingly, the magnitudes of EOF generated are comparable (within 0.5%), regardless of the hydrocarbon chain length. In 40% MeOH, the 2C 14 (EOF ,2.0% RSD) for 30 min of rinsing (,150 capillary volumes). This is consistent with the dramatic improvement in stability observed in aqueous phosphate buffers upon switching from 2C 12 DAB to 2C 18 DAB [37].…”

Section: Dialkyldimethyl Ammonium Bromide (2c N Dab)-coating Stabilitmentioning

confidence: 99%

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Semipermanent capillary coatings in mixed organic–water solvents for CE

2007

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This report describes the creation of semipermanent capillary coatings that are compatible with organic-water solvent systems in CE. The coatings are created by simply rinsing the fused-silica capillary with long double-chain cationic surfactants, such as dimethyl-ditetradecyl ammonium bromide (2C(14)DAB), dihexadecyldimethyl ammonium bromide (2C(16)DAB), and dimethyldioctadecyl ammonium bromide (2C(18)DAB). These surfactants generate semipermanent bilayer coatings on the capillary surface, which display a high degree of stability in buffers containing up to 60% v/v of organic solvents, such as methanol and ACN. The coating stability increases with increasing hydrophobicity of the surfactant, i.e., with increasing chain length. For instance, the EOF changes by only 1.2% in a 2C(18)DAB-coated capillary after 130 capillary volumes of rinsing with 60% v/v methanol containing buffer. The bilayer coatings allow separations to be performed without the need to regenerate the coating between runs or to maintain the EOF modifier in the run buffer. Rapid separations (<2 min) of anions and basic drugs with migration time reproducibility of less than 0.5% RSD and efficiencies of 0.4-0.6 million plates/m are obtained. In addition, selectivity changes for small anions and cationic drugs are also observed when the organic solvent content is adjusted.

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Section: Dialkyldimethyl Ammonium Bromide (2c N Dab)-coating Stabilitmentioning

confidence: 99%

“…All of these are based on covalent bonding of the coating to the capillary surface. As a result, these coatings are usually stable only in a restricted pH range and their preparation involves multistep processes that take a long time with significant variation between capillaries [8,10,14].…”

Section: Introductionmentioning

confidence: 99%

Semipermanent capillary coatings in mixed organic–water solvents for CE

2007

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“…A coated capillary is desirable for peptide separation and was evaluated in this work because of the reduction of interaction between the capillary wall and the analytes. In the presence of some nonaqueous electrolytes, these coated capillaries present an EOF that is not suppressed to low levels as in aqueous media [11,12]. It is important to note that such situation can offer great contributions for bioseparation solutions [13][14][15], since there will be a significant EOF with low analyte -wall interaction.…”

Section: Introductionmentioning

confidence: 94%

Nonaqueous capillary electrophoresis in coated capillaries: An interesting alternative for proteomic applications

et al. 2005

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This work brings together some contributions for the use of nonaqueous media for proteomic analysis, for both capillary electrophoresis (CE) separation and the preparation of tryptic digests. First, a ternary nonaqueous buffer consisting of 60/30/10 v/v methanol/acetonitrile/acetic acid with 12.5 mmol/L ammonium acetate was optimized for CE separation of the tryptic digest of lysozyme. Lysozyme was chosen as a model system for the protein digestion, which has also been prepared in an organic-rich medium with methanol/50 mmol/L NH(4)HCO(3), pH 8.0 (60/40 v/v). The separation results were compared to in silico (PeptideCutter program) digestion conditions, and high-efficiency peak separation (18 peaks) was obtained in 20 min with an electric field of 350 V/cm. In addition, we have evaluated the stability of a coated capillary with poly-N,N-dimethylacrylamide (60/30 cm total/effective length and 75 microm ID) for over 100 runs of tryptic digest with the nonaqueous background electrolyte solvent system. The migration times for ten selected peptide peaks presented 3-7% relative standard deviation.

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“…Capillary coatings are also highly desirable in organic solventsinvolved CE because they are very useful for the control of EOF and wall adsorption of analytes [23][24][25]. Unfortunately, only few reports focused on developing stable coatings for aqueous-organic buffers or pure organic solvents [26][27][28][29][30]. Most of the coatings were covalently bonded onto the capillary surface to obtain a satisfactory stability.…”

Section: Introductionmentioning

confidence: 99%

Use of gemini surfactants as semipermanent capillary coatings in aqueous‐organic solvents for capillary electrophoretic separation of inorganic anions

Liu

Yao

et al. 2009

J of Separation Science

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This paper proposes a new method for CE separation of inorganic anions based on the use of gemini surfactants as capillary coatings in mixed aqueous-organic solvents. The semipermanent gemini surfactant coatings were facilely prepared by rinsing the capillary with 18-s-18 solutions; they can keep be stable during the electrophoretic runs without surfactants in buffer. The coatings showed a good tolerance of methanol (MeOH) or ACN, e.g. at pH 8.0 and with 40% v/v MeOH or ACN, the EOF magnitude after 60 min of continuous electrokinetic rinsing only decreased by 2.9 or 6.0%, respectively. The coatings were successfully applied to the separation of inorganic anions. Adding organic solvents in buffer can effectively improve the resolution and efficiencies; however, it remarkably prolonged the analysis time due to the suppression of EOF. Interestingly, varying the spacer length of the gemini surfactants can also modulate (improve) the resolution but without any sacrifice of analysis time. This benefit was resulted from the unique chemical structures of gemini surfactants because it introduced a new variable, i.e. the spacer length, to the separation mechanism. IntroductionGemini surfactants are a relatively new type of surfactants, which have two hydrophobic chains and two polar headgroups linked by a spacer group [1][2][3]. Compared with the corresponding conventional (monomeric) single-chained surfactants, the gemini surfactants show better water solubility, lower critical micelle concentration, lower Krafft point, and better surface activity in aqueous solutions [2][3][4]. These features make the gemini surfactants very attractive in both academic and industrial worlds. In particular, the spacer group that can be hydrophilic or hydrophobic, flexible or rigid, heteroatomic, aromatic, etc., plays an important role in determining the solution properties of gemini surfactants [5][6][7][8][9]. In principle, the spacer group can connect any two identical or different surfactants among the available ones. Therefore, gemini surfactants are thought to be designable with an enormous variety of structures [3].Although gemini surfactants have recently generated much research interest, their applications in CE are still rare. Gemini surfactants can be good alternatives to other micelle-forming reagents, buffer additives and capillary coatings, thus it is rational to anticipate a bright prospect of application of gemini surfactants in CE. A few earlier reports described the use of gemini surfactants as micelleforming reagents in MEKC, and found that the gemini surfactants exhibit better resolution or wider migration time windows than the commonly used single-chained surfactants [10][11][12]. Warner and coworkers [13][14] and systematically studied the use of anionic gemini surfactants as pseudostationary phases in MEKC, and presented some advantages of anionic gemini surfactants compared with conventionally used SDS. Due to their lower critical micelle concentrations, the gemini surfactants can be used at much lower concentrat...

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Control of electroosmotic flow in nonaqueous capillary electrophoresis by polymer capillary coatings

Cited by 39 publications

References 36 publications

Semipermanent capillary coatings in mixed organic–water solvents for CE

Semipermanent capillary coatings in mixed organic–water solvents for CE

Nonaqueous capillary electrophoresis in coated capillaries: An interesting alternative for proteomic applications

Use of gemini surfactants as semipermanent capillary coatings in aqueous‐organic solvents for capillary electrophoretic separation of inorganic anions

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