使用真空电喷雾源的电喷雾液滴撞击二次离子质谱分析。

Electrospray droplet impact secondary ion mass spectrometry using a vacuum electrospray source.

作者信息

Takaishi R, Sakai Y, Hiraoka K, Wada H, Morita S, Nakashima T, Nonami H

机构信息

Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, 400-8511, Japan.

Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization (NARO), 496 Izumi, Fukuoka, 833-0041, Japan.

出版信息

Rapid Commun Mass Spectrom. 2015 Aug 15;29(15):1420-6. doi: 10.1002/rcm.7240.

DOI:10.1002/rcm.7240

PMID:26147482

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.

摘要

原理

在我们实验室开发的电喷雾液滴撞击（EDI）中，使用了大气压电喷雾源。为了提高离子束强度并减少抽气负载，开发了一种使用二氧化硅毛细管的真空电喷雾簇离子源。

方法

使用尖端内径为8 µm的二氧化硅毛细管进行10%甲醇水溶液的真空电喷雾。为了稳定用于纳米电喷雾的液体流速，还开发了一种自制的恒压液体泵。

结果

通过使用二氧化硅尖端纳米电喷雾发射器和恒压泵，在不使用任何加热系统（如激光照射）的情况下实现了流速为22 nL/min的稳定电喷雾。对各种样品（如温度计分子、肽、聚苯乙烯、Alq(3)、NPD、C(60)、铟和SiO(2)）进行了大气压EDI（A-EDI）和真空EDI（V-EDI）获得的质谱的比较研究。V-EDI显示出比A-EDI稍温和的电离。