Polyaniline: A conductive polymer coating for durable nanospray emitters

Maziarz, E. Peter; Lorenz, Sarah A.; White, Thomas P.; Wood, Troy D.

doi:10.1016/s1044-0305(00)00134-3

Cited by 93 publications

(76 citation statements)

References 28 publications

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“…In this type of interface, electrical contact is established in several ways: (i) a conductive capillary tip is obtained by coating the capillary outlet with a metal usually silver [6], gold [7] or polymers [8] providing electrical contact at the border between a capillary tip and the sprayer tip;…”

Section: Sheathless Interfacementioning

confidence: 99%

Capillary electrophoresis‐mass spectrometry: Recent advances to the analysis of small achiral and chiral solutes

Shamsi

Miller

2004

Electrophoresis

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We describe here the state-of-the-art development of on-line capillary electrophoresis-mass spectrometry (CE-MS) over the last two years. Technological developments included are novel designs of new interfaces and ionization sources, new capillary coatings, buffers, and micelles as well as application of various modes of CE-MS published in the recent literature. The areas of CE-MS application in analysis of small achiral and chiral solutes are covered in sections that highlight the recent advances and possibilities of each mode of CE-MS. Application areas reviewed in this paper include achiral and chiral pharmaceuticals, agrochemicals, carbohydrates, and small peptides. The separation of enantiomers using micellar electrokinetic chromatography (MEKC)-MS with molecular micelles and capillary electrochromatography (CEC)-MS using pack tapered columns appears to provide good tolerance to electrospray stability for routine on-line CE-MS. These two modes seem to be very suitable for sensitive detection of chiral pharmaceuticals in biological samples, but their use will probably increase in the near future. Overall, it seems that one mode of CE-MS, in particular capillary zone electrophoresis (CZE)-MS, is now recognized as established technique for analysis of small charged solutes, but other modes, such as MEKC-MS and CEC-MS, are still within a period of development in terms of both MS-compatible pseudostationary phases and columns as well as applications.

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Section: Sheathless Interfacementioning

confidence: 99%

Capillary electrophoresis‐mass spectrometry: Recent advances to the analysis of small achiral and chiral solutes

Shamsi

Miller

2004

Electrophoresis

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“…The emitters were prepared by pulling heated glass capillaries with the Sutter Instrument Co. P-2000 laser-based micropipette puller as described previously [50,51]. The emitters were pulled to fine open-ended tapers ranging from 1 to 5 m and coated by polyaniline (PANI) (Monsanto, St. Louis, MO) to provide conductivity needed for nanospray [52]. Previous results have shown that pulling of borosilicate glass by a laser-based micropipette puller can result in reproducible performance by mass spectrometry for different emitters created using the same pulling program protocol [51].…”

Section: Emitter Fabricationmentioning

confidence: 99%

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry

Zhao

Wood

Bruckenstein

2005

J. Am. Soc. Mass Spectrom.

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The influence of a number of redox reagents on the charge state distribution in nanoelectrospray mass spectrometry was examined using cytochrome c and ubiquitin. The redox active species investigated were: 1,4-benzoquinone, quinhydrone, tetracyanoquinodimethane (TCNQ), hydroquinone, and ascorbic acid. The redox active species was mixed with the protein sample before injection into the nanoelectrospray emitter, and mass spectra were acquired using a triple quadrupole mass spectrometer. Under the same experimental conditions, the charge state distribution of cytochrome c was observed to shift from a weighted average charge state of 14.25 (in the absence of redox species) to 7.10 in the presence of 1,4-benzoquinone. When quinhydrone was mixed with cytochrome c, the charge state distribution of the protein also shifted to lower charge states (weighted average charge state ϭ 9.43), indicative of less charge state reduction for quinhydrone than with 1,4-benzoquinone. Addition of the redox reagent had little effect on the conformation of cytochrome c, as indicated by far ultraviolet circular dichroism spectra. In contrast, the reagents TCNQ, hydroquinone, and ascorbic acid exhibited negligible effects on the observed charge state distribution of the protein. The differing results for these redox reagents can be rationalized in terms of the redox half reactions involving these species. The results observed with ubiquitin upon adding quinhydrone were analogous to those observed with cytochrome c. The multiple charging phenomenon, however, also increases the complexity of the mass spectra, and may concomitantly decrease dynamic range, reduce sensitivity, and compromise mixture component analysis [4,5]. Mass spectral deconvolution procedures are frequently useful in reducing spectral complexity [6], but are decreasingly effective as the mixture complexity increases.The charge state distributions of macromolecules can be influenced by many factors, such as the analyte structure/conformation [7][8][9][10][11] [18,20,34,35]. Many of these factors are interrelated. For example, changes in the solution pH, solvent, and heating conditions can alter the conformation of a protein, thereby affecting the observed charge state distribution. Three strategies have been reported in the literature in an effort to manipulate and simplify the observed multiple charge state distributions. One condensed-phase strategy takes place by modifying the solution conditions such as pH [36]. A second condensed-phase strategy invoked to control the observed charge state distribution in ESI is to admix base molecules with different gas-phase basicities into the analyte mixture [37]. The other strategy takes place in the gas-phase; this has been achieved either by utilizing a post ion/ion reaction within an ion-trap spectrometer to reduce multiple charge states [19, 38 -42], or by utilizing a "neutralization chamber" before the mass analyzer, to reduce multiple charge states [43][44][45][46][47]. These gas-phase approaches have demonstrated great effec...

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“…Regardless of some processing problems, this polymer has already found numerous applications in different fields. Among the others, it should be mentioned such technologies like electromagnetic shielding [4], conductive coatings [5], corrosion protection [6], artificial muscles [7], light-emitting diodes [8], field-effect transistors [9], photovoltaic cells [10] and sensors [11]. Polyaniline also can be used as an efficient catalyst in chemical technology, or as a catalyst substrate [12].…”

Section: Introductionmentioning

confidence: 99%