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Atmospheric pressure thermospray ionization using a heated microchip nebulizer
Author(s) -
KeskiRahkonen Pekka,
Haapala Markus,
Saarela Ville,
Franssila Sami,
Kotiaho Tapio,
Kostiainen Risto,
Auriola Seppo
Publication year - 2009
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4252
Subject(s) - chemistry , atmospheric pressure chemical ionization , thermospray , nebulizer , ion source , chemical ionization , ambient ionization , analytical chemistry (journal) , ionization , mass spectrometry , atmospheric pressure , photoionization , direct electron ionization liquid chromatography–mass spectrometry interface , desorption electrospray ionization , mass spectrum , chromatography , ion , selected reaction monitoring , tandem mass spectrometry , organic chemistry , medicine , oceanography , anesthesia , geology
When a standard atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) ion source is used without applying the corona discharge or photoirradiation, atmospheric pressure thermospray ionization (APTSI) of various compounds can be achieved. Although largely ignored, this phenomenon has recently gained interest as an alternative ionization technique. In this study, this technique is performed for the first time on a miniaturized scale using a microchip nebulizer. Sample ionization with the presented microchip‐APTSI ( µ APTSI) is achieved by applying only heat and gas flow to a nebulizer chip, without any other methods to promote gas‐phase ionization. To evaluate the performance of the described µ APTSI setup, ionization efficiency for a set of test compounds was monitored as the microchip positioning, temperature, nebulizer gas flow rate, sample solution composition, and solvent flow rate were varied. The µ APTSI mass spectra of the test compounds were also compared to those obtained with ESI and APCI. The µ APTSI produces ESI‐like spectra with low background noise, favoring the formation of protonated or deprotonated molecules of compounds that are ionizable in solution. Multiple charging of peptides without in‐source fragmentation was also observed. Unlike ESI, however, the µ APTSI source can tolerate the presence of mobile phase additives like trifluoroacetic acid (TFA) without significant ion suppression. The µ APTSI source can be used with standard mass spectrometer ion source hardware, being a unique alternative to the present interfacing techniques. Copyright © 2009 John Wiley & Sons, Ltd.