Online Coupling of Capillary Electrophoresis with Direct Analysis in Real Time Mass Spectrometry

Abstract

The online coupling of capillary electrophoresis with ambient direct analysis in real time mass spectrometry (DART-MS) was realized by a coaxial tip interface. The analytes eluted from capillary electrophoresis (CE) were directly ionized by the metastable helium flux produced by DART and transferred into MS for the detection, with which the online separation and simultaneous detection were achieved. The CE-DART-MS can tolerate higher concentrations of detergents and salts than traditional CE-electrospray ionization (ESI)-MS and avoided the difficulties of collecting CE effluent and cleaning the interface, which simplified the experimental procedures and shortened the analysis time. The performance of the technique was successfully verified by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) using a mixture of 4-aminoantipyrine, zolmitriptan, and quinine. This online technique showed good repeatability with the relative standard deviations (RSDs; n = 5) of 0.56-1.23% for the retention times and 2.01-7.41% for the peak areas. The quantitative analysis of 4-aminoantipyrine was accomplished in the range of 0.01-0.50 mg/mL with the linear correlation coefficient of 0.9995 and limit of detection of 14.7 fmol. Compared with CE-ESI-MS, the ion suppression effects of nonvolatile salts and detergents were efficiently minimized. The signal intensity remained constant when the concentrations reached 100 mM for sodium borate and 30 mM for SDS (in 30 mM sodium borate buffer). In addition, the proposed method was successfully applied to the detection of the endogenous caffeine in Chinese white tea.

Direct Analysis in Real Time Mass Spectrometry: a Powerful Tool for Fast Analysis

“…44 In this CE-DART-MS system, a commercial sheath liquid tip was used as the interface. A mixture of 4-aminoantipyrine, zolmitriptan, and quinine was separated and detected by capillary zone electrophoresis and micellar electrokinetic chromatography mode.…”

Advance of CE and CEC in phytochemical analysis (2012–2013)

“…Recently, direct analysis real time MS was firstly coupled to CE system (Fig. ), which can be used to directly analyze salt‐containing sample without contamination of the mass spectrometer or ion suppression . Since the limitation of nonvolatile salt/surfactant could not be used, direct analysis real time is quite a promising technique in the development of CE‐MS in analysis of phytochemicals.…”

“…Interface for online coupling of CE to ambient MS using direct analysis real time. (from with permission).…”

Sensitivity improvement of kukoamine determination by complexation with dihydrogen phosphate anions in capillary zone electrophoresis

“…Substantial efforts have been made to improve the sensitivity of CE mainly including (1) using ultra‐sensitive detectors (i.e. MS, LIF detector) ; (2) preconcentration of the analytes by off‐line procedures (like SPE and liquid–liquid extraction) or on‐line “stacking” procedures (i.e. field‐amplified sample stacking, field‐amplified sample injection), and large‐volume sample stacking) ; and (3) improving the signal response of analytes through derivatization or complexation (off‐line or online) .…”