Takaishi R, Sakai Y, Hiraoka K, Wada H, Morita S, Nakashima T, Nonami H. Electrospray droplet impact secondary ion mass spectrometry using a vacuum electrospray source.
RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015;
29:1420-1426. [PMID:
26147482 DOI:
10.1002/rcm.7240]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 05/29/2015] [Accepted: 05/30/2015] [Indexed: 06/04/2023]
Abstract
RATIONALE
In electrospray droplet impact (EDI) developed in our laboratory, an atmospheric pressure electrospray source has been used. To increase the ion beam intensity and reduce the evacuation load, a vacuum electrospray cluster ion source using a silica capillary was developed.
METHODS
A silica capillary with a tip inner diameter of 8 µm was used for vacuum electrospray using aqueous 10% methanol. To stabilize the flow rate of the liquid for nano-electrospray, a home-made constant pressure liquid pump was also developed.
RESULTS
By using the silica tip nano-electrospray emitter and a constant pressure pump, stable electrospray with flow rate of 22 nL/min was realized without using any heating system such as laser irradiation. Comparative study of mass spectra obtained by atmospheric pressure EDI (A-EDI) and vacuum EDI (V-EDI) was made for various samples such as thermometer molecule, peptide, polystyrene, Alq(3), NPD, C(60), indium, and SiO(2). V-EDI showed slightly milder ionization than A-EDI.
CONCLUSIONS
Because V-EDI gave higher target current (5-10 nA) than A-EDI (a few nA at most), V-EDI secondary ion mass spectrometry (SIMS) would be a useful technique for the surface and interface analysis.
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