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A conductive polymeric material used for nanospray needle and low-flow sheathless electrospray ionization applications
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
2002 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 74, no 1, 239-245 p.Article in journal (Refereed) Published
Abstract [en]

A conductive polypropylene/graphite mixture is used for the production of polymeric nanospray needle emitters and as a coating on fused-silica capillaries that are used for sheathless electrospray ionization (ESI). The described production of these polymeric nanospray needle emitters and sheathless ESI contacts is exceptionally easy and at a very low cost. The described polymeric nanospray emitters have shown excellent features regarding their chemical inertness and spray performance. The long-term stability of the nanospray needles exceeds 24 h of continuous use. Furthermore, the resistance to electrical discharges, which is one of the factors that often limits the lifetime of metal coated tips, has proven to be outstanding. A voltage of up to 5 kV could be applied without loss of spray performance. The use of polypropylene emitters offers a number of desirable features, as compared to silica based emitters. Among these features are mechanical flexibility and simplified regeneration of the nanospray needle. Continuous nanospray of peptides and proteins in conjunction with orthogonal time-of-flight mass spectrometry are shown with signal relative standard deviations of 5%. In addition, the polypropylene/graphite mixture has also been applied as the conductive contact for sheathless ESI in fast capillary electrophoresis separations.

Place, publisher, year, edition, pages
2002. Vol. 74, no 1, 239-245 p.
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-91885DOI: 10.1021/ac010748fOAI: oai:DiVA.org:uu-91885DiVA: diva2:164754
Available from: 2004-05-25 Created: 2004-05-25 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Development of Sheathless Electrospray Mass Spectrometry and Investigations of Associated Electrochemical Processes – A Fairy Tale
Open this publication in new window or tab >>Development of Sheathless Electrospray Mass Spectrometry and Investigations of Associated Electrochemical Processes – A Fairy Tale
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Utveckling av lågflödeselektrospray-masspektrometri samt undersökningar av associerade elektrokemiska processer – en fésaga
Abstract [en]

In microscale separations, such as capillary electrophoresis and -liquid chromatography, the liquid flow rates are in the order of nanoliters per second. If such flow rates are to be interfaced with a mass spectrometer (MS) using electrospray (ES) ionization, without loss of separation efficiency, each fraction of the analyte zone must remain undisturbed by the high voltage contact necessary for ES. One design that accomplishes this is the pure sheathless approach, where a thin, vapor deposited metal film covers the outside of the electrospray emitter tip.

This thesis describes the development of such sheathless emitters. The lifetimes of polymer embedded gold (“fairy dust”) or graphite (“black dust”) emitters were shown to by far exceed those of previously used conductive films. In addition, the production of emitters with these coatings was substantially simplified. The increase in durability was found to be due to enhanced resistance towards the electrochemical processes associated with ES. In analogy, the reasons for the limited durability of previously used methods were correlated with their tendency to oxidize, or be mechanically removed, during electrochemical reactions.

Electrochemical processes associated with the electrospray potential were also found to seriously disturb analyses in which porous graphitic carbon was used as the separation medium. A proper choice of grounding point locations eliminated these disturbances.

At last, the differences regarding analytical performance of several sheathless interface configurations, used in capillary liquid chromatography, were examined. The best performance was obtained when a pure sheathless emitter with a conductive layer of polyimide and graphite was coupled to the LC column through a Teflon sleeve.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 41 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 989
Keyword
Analytical chemistry, electrospray, sheathless, mass spectrometry, capillary electrophoresis, electrochemistry, chromatography, interface, fairy dust, gold, Analytisk kemi
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-4293 (URN)91-554-5989-7 (ISBN)
Public defence
2004-09-10, Room B 41, BMC - Uppsala Biomedical Center, Husargatan 3, Uppsala, 10:15
Opponent
Supervisors
Available from: 2004-05-25 Created: 2004-05-25Bibliographically approved
2. Electrifying the Molecules of Life: Peptide and Protein Analysis by Capillary Electrophoresis Coupled to Electrospray Ionization Mass Spectrometry
Open this publication in new window or tab >>Electrifying the Molecules of Life: Peptide and Protein Analysis by Capillary Electrophoresis Coupled to Electrospray Ionization Mass Spectrometry
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the current status and novel aspects of the analysis of the molecules of life, i.e. peptides and proteins, using capillary electrophoresis (CE) coupled to mass spectrometry (MS) via (sheathless) electrospray ionization (ESI). Early reports of sheathless CE-ESI-MS were plagued by limited lifetimes of the electrospray emitter. In this thesis, two new approaches, the Black Dust and the Black Jack methods, utilizing polymer-embedded graphite instead of noble metals are presented. These emitters have shown improved long-term stability and proven excellent for sheathless electrospray operation. Failure of an emitter is often caused by electrochemical reactions occurring at the emitter-liquid interface. The electrochemical properties of the graphite coated emitters were therefore evaluated by classical electrochemical methods, such as cyclic voltammetry and chronoamperometry. The graphite coated emitters showed excellent electrochemical stability and properties compared to noble metal and polymer configurations.

Analyte-wall interactions have long been known to cause problems in the CE analysis of biomolecules. This can be circumvented by internal modification of the capillary walls. Additionally, it is of outermost importance to have a stable and sufficiently high electroosmotic flow (EOF) to sustain the electrospray, when using a sheathless approach. New monomer and polymer coatings are presented for rapid and high-efficient CE-ESI-MS separations of peptides and proteins.

Furthermore, the use of CE-ESI coupled to Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) shows great potential for rapid proteomic probing of human cerebrospinal fluid. The results are comparable with more established techniques, such as liquid chromatography and two-dimensional gel electrophoresis coupled to MS. However, the CE-ESI-FTICRMS analysis has significantly lower sample consumption and faster analysis time compared to the other techniques. The applications and use of CE-ESI-MS is expected to have a bright future with continued growth as current trends of multidimensional hyphenation and microfabricated devices are further developed and explored.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 44 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 969
Keyword
Analytical chemistry, Capillary electrophoresis (CE), Electrospray ionization (ESI), Mass spectrometry (MS), Peptides, Proteins, Cerebrospinal fluid (CSF), Graphite coating, Monomer coating, Polymer coating, Analytisk kemi
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-4233 (URN)91-554-5947-1 (ISBN)
Public defence
2004-05-19, B:41, BMC, Uppsala, 13:15
Opponent
Supervisors
Available from: 2004-04-20 Created: 2004-04-20 Last updated: 2012-02-08Bibliographically approved

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Wetterhall, MagnusBergquist, Jonas

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