Characterisation of inner surface and adsorption phenomena in fused-silica capillary electrophoresis capillaries

Kaupp, Stefan; Steffen, R.; Wätzig, Hermann

doi:10.1016/0021-9673(96)00441-4

Cited by 38 publications

(24 citation statements)

References 18 publications

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“…Although the proteins are enveloped by negatively charged SDS molecules, adsorption to the capillary wall still takes place. This can be shown by scanning electron microscopy [41]. While a monomolecular layer is strongly adsorbed, the following layers are more loosely bound [39].…”

Section: Preliminary Experimentsmentioning

confidence: 95%

“…0.1 M NaOH (see above) and methanolcontaining SDS buffer are principally suitable, but current irregularities still occurred and thus drop-outs during sample series were observed. Etching of the capillary by hydrofluoric acid treatment should smoothen the capillary surface [41]. Possible binding sites and hence the degree of adsorption should be decreased.…”

Section: Rinsingmentioning

confidence: 99%

“…A systematic investigation of sodium hydroxide washings for plasma samples revealed a ratio of ³ 12% drop-outs (n = 457) [36]. As shown by SEM, even after SDS rinsing, considerable amounts of proteins remain adsorbed [41,42]. The amount of firmly adsorbed proteins was estimated to be at least 1% [42].…”

Section: Introductionmentioning

confidence: 98%

“…Frequently, even irreversible clogging of the capillary was observed. Adsorption patterns were verified by scanning electron microscopy (SEM) [41]. The commonly used sodium hydroxide rinsing steps cannot prevent routinely observed analytical drop-outs.…”

Section: Introductionmentioning

confidence: 99%

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Micellar electrokinetic capillary chromatography as a powerful tool for pharmacological investigations without sample pretreatment: A precise technique providing cost advantages and limits of detection to the low nanomolar range

Kunkel

Wätzig

1999

Electrophoresis

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Section: Preliminary Experimentsmentioning

confidence: 95%

Section: Rinsingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Micellar electrokinetic capillary chromatography as a powerful tool for pharmacological investigations without sample pretreatment: A precise technique providing cost advantages and limits of detection to the low nanomolar range

Kunkel

Wätzig

1999

Electrophoresis

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“…This strongly impairs separation performance and reproducibility leading to increasing migration times and peak broadening [14,15] . Adsorption patterns have been verified by scanning electron microscopy (SEM) [16] . The commonly used sodium hydroxide rinsing steps cannot prevent analytical drop outs which are routinely observed (ref.…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetic Investigations with Direct Injection of Plasma Samples: Possible Savings Using Capillary Electrophoresis (CE)

Kunkel¹,

Wätzig²

1999

Arch. Pharm. Pharm. Med. Chem.

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Capillary electrophoresis (CE) is often regarded as a separation technique of choice because of its high selectivity and its cost advantages compared to LC. RSD% of 0.5% have become standard for quality control assays. Using CE, sample pretreatment can often be significantly reduced, leading to notable savings of labor and reagent costs. Moreover, errors from sample pretreatment steps are avoided. A number of pharmaceuticals (e.g. acetaminophen, salicylic acid, sulfamethoxazole, theophylline, tolbutamide, and trimethoprim) have been determined in human plasma on underivatized fused silica capillaries by MEKC without sample pretreatment, the total analysis time being only 10 min. An sodium dodecyl sulfate‐containing borate buffer (60 mM with 200 mM SDS) at pH 10 has been used. Between runs, proteins adsorbed to the capillary wall are removed by a rinsing regimen consisting of SDS buffer and either acetonitrile (e.g. 50% v/v) or isopropanol (e.g. 10% v/v). Other rinsing approaches are discussed (salts, enzyme containing solutions, organic solvents, sodium hydroxide, hydrofluoric acid). The separation system is tested in a concentra‐tion range between 10 ng/mL and 100 μg/mL, the detection limit being about 5 ng/mL. The sensitivity has been substantially improved compared to preceding work using field‐amplified injection mechanisms and efficient computer algorithms that take advantage of multiwavelength detection. Correlations between the limit of quantitation (LOQ), the limit of detection (LOD) and the signal/noise ratio are discussed. A day‐to‐day precision for relative peak areas of 1 to 2% relsdv (n > 40) has been reached in the upper concentration range. Thus, not only drug monitoring but also pharmacokinetic investigations from blood plasma have become possible without further sample pretreatment.

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Fused-silica capillaries for capillary electrophoresis and gas chromatography: Inner surface corrosion, within-batch differences, and influence of drawing parameters studied by atomic force microscopy

Kaupp

Wätzig

1999

Electrophoresis

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Characterisation of inner surface and adsorption phenomena in fused-silica capillary electrophoresis capillaries

Cited by 38 publications

References 18 publications

Micellar electrokinetic capillary chromatography as a powerful tool for pharmacological investigations without sample pretreatment: A precise technique providing cost advantages and limits of detection to the low nanomolar range

Micellar electrokinetic capillary chromatography as a powerful tool for pharmacological investigations without sample pretreatment: A precise technique providing cost advantages and limits of detection to the low nanomolar range

Pharmacokinetic Investigations with Direct Injection of Plasma Samples: Possible Savings Using Capillary Electrophoresis (CE)

Fused-silica capillaries for capillary electrophoresis and gas chromatography: Inner surface corrosion, within-batch differences, and influence of drawing parameters studied by atomic force microscopy

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