Remote sampling mass spectrometry for dry samples: Sheath-flow probe electrospray ionization (PESI) using a gel-loading tip inserted with an acupuncture needle

Dilshadbek T Usmanov; Khatam B Ashurov; Satoshi Ninomiya; Kenzo Hiraoka; Hiroshi Wada; Hiroshi Nakano; Masaya Matsumura; Sachiyo Sanada-Morimura; Hiroshi Nonami

doi:10.1002/rcm.8045

Remote sampling mass spectrometry for dry samples: Sheath-flow probe electrospray ionization (PESI) using a gel-loading tip inserted with an acupuncture needle

Rapid Commun Mass Spectrom. 2018 Mar 15;32(5):407-413. doi: 10.1002/rcm.8045.

Authors

Dilshadbek T Usmanov^{1

2}, Khatam B Ashurov², Satoshi Ninomiya³, Kenzo Hiraoka¹, Hiroshi Wada⁴, Hiroshi Nakano⁴, Masaya Matsumura⁵, Sachiyo Sanada-Morimura⁵, Hiroshi Nonami⁶

Affiliations

¹ Clean Energy Research Center, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi, 400-8511, Japan.
² Institute of Ion-Plasma and Laser Technologies, Durmon Yoli Street 33, 100125, Tashkent, Uzbekistan.
³ Graduate School, Department of Interdisciplinary Research, University of Yamanashi, 4-3-11, Takeda, Kofu, 400-8511, Japan.
⁴ Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, 496 Izumi, Chikugo, Fukuoka, 833-0041, Japan.
⁵ Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Suya 2421, Goshi, Kumamoto, 861-1192, Japan.
⁶ Plant Biophysics/Biochemistry Research Laboratory, Faculty of Agriculture, Ehime University, Matsuyama, 790-8566, Japan.

PMID: 29235697
DOI: 10.1002/rcm.8045

Abstract

Rationale: Probe electrospray ionization (PESI) is only applicable to liquid or wet samples. In this study, a sheath-flow PESI method for remote sampling mass spectrometry that can be applied to dry samples was developed.

Methods: An acupuncture needle (0.12 mm outer diameter, 700 nm tip diameter) was inserted into a gel-loading tip with a 0.1 mm protrusion out of the tip. Analytes were extracted by filling the latter tip with solvent and softly touching the sample surface for a short time (<1 s). A high voltage was applied to the acupuncture needle, and mass spectra of analytes were obtained by self-aspirating electrospray.

Results: Dry samples, such as lines of ballpoint pen ink on paper, pharmaceutical tablets, instant coffee, brown rice, and narcotics, gave strong ion signals. The sample carryover was negligible. The sequential electrospray was observed to be similar to conventional PESI. The limits of detection (LODs) for morphine and rhodamine B were found to be of the order of picograms.

Conclusions: Because of its simplicity and versatility, sheath-flow PESI is a promising technique for on-site and nondestructive profile analysis of dry samples with bulky and complicated shapes, with a spatial resolution of ~0.3 mm.