Advantages of Pressurization in Capillary Electrophoresis/Electrospray Ionization Mass Spectrometry

Abstract

In this paper we present a simple interface for coupling capillary electrophoresis (CE) to mass spectrometry (MS) which can operate without significant user intervention. The use of a dedicated interface allows rapid changeover between CE/MS and liquid chromatography (LC)/MS, which is particularly important as CE and LC are often used on the same mass spectrometer. The suitability of the interface construction is illustrated on a triple quadrupole mass spectrometer and a high-resolution time-offlight mass spectrometer with compounds such as peptides, vitamins, and carbohydrates. Separations of these compounds are also used to evaluate the robustness of the CE-MS interface under pressurized and nonpressurized modes of operation. The simultaneous application of pressure and voltage overcomes two of the major problems commonly encountered when coupling CE to MS, i.e. unreliable long-term operation and protracted analysis times due to the long separation capillaries needed to connect to the mass spectrometer. Concomitant application of high voltage and hydrostatic pressure significantly reduces analysis time without compromising the overall separation. It was observed that pressurized CE exhibits less run-to-run-variations, leading to run-to-run repeatability better than 0.5% for migration time and below 5% for peak area with the MS as detector.

Capillary electrophoresis – mass spectrometry: 15 years of developments and applications

“…11 with the changes in solution flow in the capillary as a function of the sheath gas at different pH (25 kV effective voltage, 73 cm fused-silica capillary, 50 mm ID, 10 mM buffers). Other possibilities to reduce analysis time were demonstrated by pressurising the system [85] or using a subatmospheric electrospray interface [96], adding a hydrodynamic flow to the EOF (with the adverse implications already discussed in Section 2).…”

Coupling CE with atmospheric pressure photoionization MS for pharmaceutical basic compounds: Optimization of operating parameters

“…This interface is the critical part in the connection of both instruments and the main reason that CE-ESI/MS is not considered a routine technique. Currently, the commercial sheath liquid configuration, where an additional liquid is mixed to the CE effluent, is the most rugged and easy tool to implement CE-ESI/MS [5][6][7][8][9][10]. Sheath liquid provides (i) electrical contact with the outlet end of the separation capillary, (ii) appropriate flow rate adapted to source configuration, and (iii) suitable solvent conditions for ionization and evaporation, independent on the nature of the BGE.…”

Overview on advances in capillary electrophoresis‐mass spectrometry of carbohydrates: A tabulated review

“…Table 1 (see Addendum) reports some selected examples of such application. Typically, carbohydrates carrying ionizable groups, like carrageenan oligosaccharides [51], or carboxymethylated and quaternary ammonium-CDs [47] are not derivatized. Neutral saccharides, on the contrary, are normally linked to negatively charged tags like p-amino benzoic acid (p-ABA) [42], 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) [48], APTS [49], 7-amino-1,3-naphthalene disulfonic acid (ANDSA) [50] or, more rarely, to positively charged molecules, like 3-(acetylamino)-6-aminoacridone (AA-Ac) [52].…”

“…To date, the main articles regarding the CE-MS of saccharidic compounds found in literature include the analysis of (i) standard mixtures [42,[47][48][49][50][51][52]; (ii) carbohydrates in nutrition [19,[53][54][55][56][57][58][59]; (iii) glycans from glycoproteins [60][61][62][63][64][65]; (iv) carbohydrates in drug development [45,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81].…”