Evaluation of a microchip electrophoresis-mass spectrometry platform deploying a pressure-driven make-up flow

Abstract

Integration of a pressure-driven make-up flow (MUF) into a microchip electrophoresis (MCE) platform in order to facilitate its coupling with electrospray ionization-mass spectrometric detection (ESI-MS) is described. In the glass /PDMS hybrid microchip, a MUF channel was made to intersect with the MCE separation channel at an angle of 45° The MUF was generated by a syringe pump. Microscopic image results from simulation studies showed that the pressure-driven MUF and the potential-driven electroosmotic flow in the MCE separation channel could be run separately without interfering with each other and mixed well at the joint point by adjusting either the MUF flow rate or the potential applied for MCE separation. The MUF had several desirable functions, including making the start of electrospray easy and cleaning the nanoESI emitter continuously when not spraying. High separation efficiency was achieved with the proposed MCE-nanoESI-MS system in separating an amino acid mixture containing glutamine, serine, threonine, phenylalanine, and glutamic acid. All of them were baseline separated from each other within 3 min. Plate numbers of >10,000 (on a 2.5 cm MCE separation channel) were obtained. The analytical platform also showed a linear response for quantification of DOPA with a detection limit (S/N =3) of 0.10 μM. In addition, on-line derivatization of MCE elutes in order to enhance MS detection sensitivity was easily carried out by adding the tagging reagent into the MUF. These results indicated that the present system might have a good potential in MCE-MS applications.

A microchip electrophoresis-mass spectrometric platform with double cell lysis nano-electrodes for automated single cell analysis

“…Based on the recent development of several MCE-MS microchips in our lab [28, 29, 33], the present design was intended to achieve automated single cell analysis. A major change in the design is integrating two gold nano-electrodes into the microchip for single cell lysis by using the double electrode technique [34–37].…”

“…The chip was composed of a glass substrate (Telic Company, Valencia, CA) and a PDMS cover bearing the channels. The procedure used to create channels in the PDMS cover was described previously [28,29]. Briefly, to create a master for fabricating the PDMS covers, a silicon wafer was coated with HMDS and then with SU-8 2010 negative photoresist using a spin coater.…”

Recent Developments of Microchip Capillary Electrophoresis Coupled with Mass Spectrometry

“…As an alternative to an electro-osmotic delivery of solvent, Li et al have described the usage of a pressure-driven makeup flow [88]. The chip design was similar to that of Ramsey's group, with a side channel merging with the CE separation channel at an angle of 45 ∘ (Figure 4.11).…”

Real‐Time Chiral Metabolic Monitoring of Single Cell Using Microchip Electrophoresis Coupled with Electrospray Ionization Mass Spectrometry

“…The cell liquid moves from separation channel to MUF for entry into the mass spectrum. The voltage for G3 has an effect to spray in the cells analysis process, the electrode voltage was fixed at 1.5 kV to be best proficiency as previously reported . No interference was observed in the process of single cell lysis and measuring.…”