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Sheathless interface to match flow rate of capillary electrophoresis with electrospray mass spectrometry using regular‐sized capillary
Author(s) -
Yin Yue,
Li Gongyu,
Guan Yafeng,
Huang Guangming
Publication year - 2016
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.7621
Subject(s) - chemistry , capillary electrophoresis , capillary action , capillary electrophoresis–mass spectrometry , electrospray , electrospray ionization , chromatography , analytical chemistry (journal) , capillary electrochromatography , mass spectrometry , volumetric flow rate , capillary length , extractive electrospray ionization , sample preparation in mass spectrometry , materials science , physics , quantum mechanics , composite material
Rationale The flow rate match has been a great challenge when coupling capillary electrophoresis (CE) with electrospray ionization mass spectrometry (ESI‐MS). Conventional CE‐ESI‐MS interfaces used liquid sheath flow, narrowed capillary or additional pressure to meet this requirement; sacrifice of either capillary inner diameter (i.d.) or separation efficiency is often inevitable. Thus, a regular‐sized capillary‐based sheathless interface would be attractive for flow rate match in CE‐MS. Methods The regular‐sized capillary‐based CE‐MS interface was achieved by coupling CE with induced electrospray ionization (iESI) which was stimulated by the fact that the iESI could both achieve flow rate down to 0.2 μ L/min and retain ionization efficiency. The CE‐iESI‐MS interface was completed with an intact separation capillary, outside the outlet end of which a metal electrode was attached for the application of alternating current (ac) high voltage (HV). Results The feasibility of this CE‐iESI‐MS interface was demonstrated through the stable total ion chromatograms obtained by continuous CE infusion of tripropylamine with regular‐sized capillaries. Tripropylamine and atenolol were separated and detected successfully in phosphate buffer solution (PBS) by CE‐iESI‐MS using a 50 or 75 μ m i.d. capillary. Furthermore, this new interface showed a better signal‐to‐noise (S/N) of 3 to 7 times enhancement compared with another sheathless CE‐ESI‐MS interface that using one high voltage for both separation and electrospray when analyzing the mixture of tripropylamine and proline in NH 4 OAc buffer. In addition, the reproducibility of this interface gave satisfactory results with relative standard deviation (RSD) in retention time in the range between 1% and 3%. Conclusions The novel sheathless CE‐MS interface introduced here could match conventional electroosmotic flow (EOF) with electrospray which could also preserve the separation efficiency and sensitivity of CE‐MS. This newly developed CE‐iESI‐MS interface was also demonstrated to be effective for different buffers, PBS and NH 4 OAc, without any additives such as methanol and acetic acid. Hence, we believe that this sheathless CE‐MS interface could be operated with other nonvolatile and volatile buffers. Copyright © 2016 John Wiley & Sons, Ltd.