A simple method for fabrication of silver‐coated sheathless electrospray emitters

Chen, Yet-Ran; Her, Guor‐Rong

doi:10.1002/rcm.940

Cited by 33 publications

(19 citation statements)

References 25 publications

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“…In its most recent version, CE capillary is carefully sharpened, i.e., by etching the outer capillary wall with hydrofluoric acid (HF) [44,88,[104][105][106] or mixtures of sulfuric and phosphoric acid [90], by mechanical shapening with an abrasive, by flameor laser-heated pulling [88,[107][108][109][110] or a combination of several techniques [37]. Kriger et al [109] reported a further cleaning subsequent to capillary sharpening by means of a so-called "piranha solution" (mixture of H 2 O 2 and sulfuric acid).…”

Section: Sheathless Interface (Nanospray)mentioning

confidence: 99%

Advances in the analysis of proteins and peptides by capillary electrophoresis with matrix‐assisted laser desorption/ionization and electrospray‐mass spectrometry detection

2005

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High throughput, outstanding certainty in peptide/protein identification, exceptional resolution, and quantitative information are essential pillars in proteome research. Capillary electrophoresis (CE) coupled to mass spectrometry (MS) has proven to meet these requirements. Soft ionization techniques, such as matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI), have paved the way for the story of success of CE-MS in the analysis of biomolecules and both approaches are subject of discussion in this article. Meanwhile, CE-MS is far away from representing a homogeneous field. Therefore the review will cover a vast area including the coupling of different modes of CE (capillary zone electrophoresis, capillary isoelectric foscusing, capillary electrochromatography, micellar electrokinetic chromatography, nonaqueous capillary electrophoresis) to MS as well as on-line preconcentration techniques (transient capillary isotachophoresis, solid-phase extraction, membrane preconcentration) applied to compensate for restricted detection sensitivity. Special attention is given to improvements in interfacing, namely addressing nanospray and coaxial sheath liquid design. Peptide mapping, collision-induced dissociation with subsequent tandem MS, and amendments in mass accuracy of instruments improve information validity gained from MS data. With 2-D on-line coupling of liquid chromatography (LC) and CE a further topic will be discussed. A special section is dedicated to recent attempts in establishing CE-ESI-MS in proteomics, in the clinical and diagnostic field, and in the food sector.

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Section: Sheathless Interface (Nanospray)mentioning

confidence: 99%

Advances in the analysis of proteins and peptides by capillary electrophoresis with matrix‐assisted laser desorption/ionization and electrospray‐mass spectrometry detection

2005

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“…A sheath or make-up flow [5][6][7] can be used to mix with the CE effluent at the outlet to establish the electrical contact. While for sheathless interfaces the electrical contact was established by direct application of high voltage (HV) via a conductive coating at the capillary tip, [8][9][10][11] through a liquid junction by inserting a narrow metal wire into the capillary outlet or utilization of a stainless steel tip, [12][13][14][15] or just through the CE high voltage. [16][17][18] However, problems such as coating damage and formation of air bubbles [19] may occur at the physical interface between the electrode and the buffer solution.…”

Section: Methodsmentioning

confidence: 99%

Sheathless interface to match flow rate of capillary electrophoresis with electrospray mass spectrometry using regular‐sized capillary

Yin

Guan

et al. 2016

Rapid Comm Mass Spectrometry

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RATIONALE:The flow rate match has been a great challenge when coupling capillary electrophoresis (CE) with electrospray ionization mass spectrometry (ESI-MS). Conventional CE-ESI-MS interfaces used liquid sheath flow, narrowed capillary or additional pressure to meet this requirement; sacrifice of either capillary inner diameter (i.d.) or separation efficiency is often inevitable. Thus, a regular-sized capillary-based sheathless interface would be attractive for flow rate match in CE-MS. METHODS:The regular-sized capillary-based CE-MS interface was achieved by coupling CE with induced electrospray ionization (iESI) which was stimulated by the fact that the iESI could both achieve flow rate down to 0.2 μL/min and retain ionization efficiency. The CE-iESI-MS interface was completed with an intact separation capillary, outside the outlet end of which a metal electrode was attached for the application of alternating current (ac) high voltage (HV). RESULTS: The feasibility of this CE-iESI-MS interface was demonstrated through the stable total ion chromatograms obtained by continuous CE infusion of tripropylamine with regular-sized capillaries. Tripropylamine and atenolol were separated and detected successfully in phosphate buffer solution (PBS) by CE-iESI-MS using a 50 or 75 μm i.d. capillary. Furthermore, this new interface showed a better signal-to-noise (S/N) of 3 to 7 times enhancement compared with another sheathless CE-ESI-MS interface that using one high voltage for both separation and electrospray when analyzing the mixture of tripropylamine and proline in NH 4 OAc buffer. In addition, the reproducibility of this interface gave satisfactory results with relative standard deviation (RSD) in retention time in the range between 1% and 3%. CONCLUSIONS: The novel sheathless CE-MS interface introduced here could match conventional electroosmotic flow (EOF) with electrospray which could also preserve the separation efficiency and sensitivity of CE-MS. This newly developed CE-iESI-MS interface was also demonstrated to be effective for different buffers, PBS and NH 4 OAc, without any additives such as methanol and acetic acid. Hence, we believe that this sheathless CE-MS interface could be operated with other nonvolatile and volatile buffers. Copyright © 2016 John Wiley & Sons, Ltd.The combination of capillary electrophoresis (CE) and mass spectrometry (MS) [1][2][3] has become a powerful technique for separation and detection of a broad range of compounds since it was introduced in the late 1980s. [4] To date, electrospray ionization (ESI) has been the most frequently used interface for CE-MS coupling. However, there are two major challenges when interfacing CE with ESI-MS. One is to maintain a constant electrical contact for both CE separation and the ESI process. A sheath or make-up flow [5][6][7] can be used to mix with the CE effluent at the outlet to establish the electrical contact. While for sheathless interfaces the electrical contact was established by direct application of high voltage (HV) via a conductiv...

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“…In this approach, conductive rubber instead of carbon coating [10] or silver coating [24] was used to coat the tip. The conductive rubber kit which is often used in repairing and modifying printed circuits was used to coat the sprayer.…”

Section: Conductive Rubber Coatingmentioning

confidence: 99%

“…However, resolution may somewhat degrade because of the production of the laminar flow in a pressure-driven system [30,31]. Another strategy, which is often adopted, is the use of a tapered tip with 20 mm or less od [22][23][24][25]. Nevertheless, the susceptibility to breaking or clogging of the tip during coating or sample analysis limits the application of tapered tips having small orifices [32].…”

Section: Introductionmentioning

confidence: 99%

“…In sheathless interface, several approaches including a pulled bare fused-silica capillary emitter, the conductive coating, connecting to a stainless-steel tip, and the use of a liquid junction [14,[10][11][12][22][23][24][25][26][27][28][29] have been proposed to maintain electrical continuity of the electrophoresis circuit. An important consequence of sheathless design is that the sample bands are not diluted.…”

Section: Introductionmentioning

confidence: 99%

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Sheathless capillary electrophoresis‐mass spectrometry using a pulsed electrospray ionization source

Chao

Chen

et al. 2006

Electrophoresis

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A sheathless interface has been developed for coupling CE with electrospray IT mass spectrometer. This interface utilized a pulsed ESI source. The use of a pulsed electrospray source allows the use of a sprayer with larger orifice, and thus alleviates the problem of column clogging during conductive coating and CE analysis. A pulsed ESI source operated at 20 Hz and 20% duty cycle was found to produce the optimal signals. For better signals, the maximum ion injection time in the IT mass spectrometer has to be set to a value close to the actual spraying time (10 ms). Using a sprayer with 50 microm od, more stable and enhanced signals were obtained in comparison with continuous CE-ESI-MS under the same flow rate (150 nL/min). The utility of this design is demonstrated with the analysis of synthetic drugs by CE-MS.

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A simple method for fabrication of silver‐coated sheathless electrospray emitters

Cited by 33 publications

References 25 publications

Advances in the analysis of proteins and peptides by capillary electrophoresis with matrix‐assisted laser desorption/ionization and electrospray‐mass spectrometry detection

Advances in the analysis of proteins and peptides by capillary electrophoresis with matrix‐assisted laser desorption/ionization and electrospray‐mass spectrometry detection

Sheathless interface to match flow rate of capillary electrophoresis with electrospray mass spectrometry using regular‐sized capillary

Sheathless capillary electrophoresis‐mass spectrometry using a pulsed electrospray ionization source

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