Two-dimensional capillary electrophoresis-mass spectrometry (CE-CE-MS): coupling MS-interfering capillary electromigration methods with mass spectrometry

Abstract

Electromigration separation techniques often demand certain compounds in the electrolyte to achieve the required selectivity and efficiency. These compounds, including the electrolyte itself, ampholytes, polymeric compounds for sieving, complexing agents, tensides, etc. are often non-volatile. Thus, interference with the electrospray ionization process is a common issue, impeding direct coupling of such electrolyte systems to mass spectrometry. Still, several options exist to obtain mass spectra after separation, including offline fractionation, alternative ionization, dilution, or the change to volatile constituents. In the first part of this article, these methods are discussed. However, all of these options are a compromise of separation performance and sensitivity of mass spectrometric detection. Two-dimensional capillary electrophoresis-mass spectrometry (CE-CE-MS) systems represent a promising alternative to the aforementioned challenges, as they allow the use of existing methods with best separation performance in combination with sensitive mass characterization. In this context, the second part of this article is dedicated to the advantages, limitations, and applications of this approach. Finally, an outlook towards future developments is given.

Intact monoclonal antibodies separation and analysis by sheathless capillary electrophoresis-mass spectrometry

“…Since 2010, some reports described CZE-based methods for the characterization of mAbs charges variants for the quality control of biopharmaceutical companies in terms of product heterogeneity. [11][12][13][14]18 To date, two reports from Ruesch's group represents a reference for the analysis of mAbs using CZE with a UV detection. 11,15 Nevertheless, no structural information can be detailed for the basic and/or acidic variants.…”

“…This last decade, separation of intact mAbs have been studied with several electrophoretic techniques such as CZE, 2D-CE-MS and CZE-MS. [11][12][13][14] He et al were precursor in the field of intact mAbs separation using CZE-UV. They developed a rapid method using "-amino-caproic acid (EACA) and triethylenetetramine (TETA) as background electrolyte (BGE), and hydroxypropylmethyl cellulose (HPMC) as dynamic neutral coating of the capillary.…”

Insights from capillary electrophoresis approaches for characterization of monoclonal antibodies and antibody drug conjugates in the period 2016–2018

“…While some very recent articles describing improvement of CZE-ESI-MS or cIEF-ESI-MS applications for mAbs charge variants characterization [67,103,104], another recent approach have been developed to reduce BGE impact on CE-ESI-MS detection. Inspired by 2D LC-MS, the group of Prof. Neusüβ worked on a promising 2D CE-MS setup, pursuing to provide interference-free mass spectra with electrophoretic separations [105]. This advanced separation technique includes a first dimension which allows to perform a high resolving CE separation with nonvolatile BGEs followed by a second dimension able to fully remove the ESI-interfering components from the analytes prior to MS detection.…”

Revealing the potential of capillary electrophoresis/mass spectrometry: the tipping point

“…Schematic representations of the instrumental settings implemented to perform 2D‐CE/ESI‐MS experiments . Copyright (2018) John Wiley and Sons, Ltd…”