Analytical Properties of Solid-substrate Electrospray Ionization Mass Spectrometry

Abstract

Abstract. Conventional electrospray ionization mass spectrometry (ESI-MS) uses a capillary for sample loading and ionization. Along with the development of ambient ionization techniques, ESI-MS using noncapillary emitters has attracted more interest in recent years. Following our recent report on ESI-MS using wooden tips (Anal. Chem. 83, 8201-8207 (2011)), the technique was further investigated and extended in this study. Our results revealed that the wooden tips could serve as a chromatographic column for separation of sample components. Sequential and exhaustive ionization was observed for proteins and salts on wooden tips with salts ionized sooner and proteins later. Nonconductive materials that contain microchannels/pores could be used as tips for ESI-MS analysis with sample solutions loaded to the sharp-ends only, since rapid diffusion of sample solutions by capillary action would enable the tips to become conductive. Tips of inert materials such as bamboo, fabrics, and sponge could be used for sample loading and ionization, while samples such as tissue, mushroom, and bone could form tips to induce ionization for direct analysis with application of a high voltage.

Ionization Suppression and Recovery in Direct Biofluid Analysis Using Paper Spray Mass Spectrometry

“…After the solvent has wicked to the tip of the paper (typically within seconds), electrospray ionization is induced at the sharp tip of the wet paper via the application of a high voltage. Analytes are typically detected immediately, although separation effects have been reported in some cases [35,36]. Analyte signal can last for several minutes, allowing multiple analytes to be analyzed by MS n .…”

Electrospray Ionization on Solid Substrates

“…10) e use of cellulose-based materials, e.g., cotton wick and paper, for ESI was rst reported by Fenn in 2001. 28) In recent years, solid-substrate ESI using chromatography paper, termed as paper spray, 29,30) and wooden tip, termed as wooden-tip ESI, 31) were developed.…”

“…Sequential and exhaustive ionization was also observed in wooden-tip ESI with an order di erent from that in PESI, 22) enabling separated ionization of salts and proteins thus direct analysis of protein samples with high salt content by the technique. 10) More recently, we demonstrated the application of woodentip ESI in direct detection and quantitation of drugs-ofabuse in raw oral uid and urine with acceptable sensitivity, linear range, accuracy and precision 42) (Figs. 4(c) & (d)).…”

“…3,4) However, these capillary-based prototypes of ESI have a number of limitations. First, the use of capillary for sample introduction is easily susceptible to clogging, [5][6][7][8][9][10][11][12] and sample loading into capillaries, particularly nano-ESI capillaries, is not very convenient. In addition, the capillaries used in conventional ESI, typically made of stainless steel and fused silica, 5) only serve for sample loading and ionization, and complex samples usually require time-consuming sample preparation and chromatographic separation prior to ESI-MS analysis.…”

“…As the use of capillary is not involved, sampling with these techniques is free from clogging. [5][6][7][8][9][10][11][12] Moreover, the feature of open-surface sampling allows high exibility in the sampling materials. Separation of components in the sample is possible when materials with separating properties, e.g., cellulose-based materials and chromatographic media, are applied as the substrates.…”