The development of a two‐leveled two cross interface for on‐line coupling solid‐phase extraction and capillary electrophoresis‐mass spectrometry

Abstract

A two-leveled, two cross PDMS-based interface for on-line coupling of SPE with CE-MS was proposed. In this interface, the SPE column and the CE separation column were positioned orthogonally and two crosses were fabricated on the interface. With the two cross design, the operation of SPE could be performed independently without unexpected flow through leakage into the separation column. The performance of the interface was optimized using a peptide mixture. The position of the SPE column related to the CE separation channel was found to be critical to the performance of the system. Under the optimal position, the separation efficiency was similar to a CE-MS experiment without SPE. The peptide signals were enhanced 50- to 100-fold and the repeatability was within 4% RSD for migration time and 10% RSD for peak area. A tryptic digest of cytochrome c was used to demonstrate the feasibility of the interface in protein identification at a level of 1 ng/microL.

Staggered multistep elution solid‐phase extraction capillary electrophoresis/tandem mass spectrometry: a high‐throughput approach in protein analysis

“…The SPE‐CE/MS system, which consists of a PDMS‐based two‐leveled two‐cross SPE‐CE interface and a low‐sheath‐flow CE/MS interface (Fig. ), has been described previously . Briefly, a syringe pump (Harvard Apparatus, MA, USA) was used to deliver the running buffer.…”

A Miniaturized Transverse Flow Gating Interface for the On-line Coupling of Solid-phase Extraction with Capillary Electrophoresis

“…As a result, we deemed the acceptable sample flow rate should be lower than 45 μL/min. As the effluent flow rates are typically in the range of 3.3 -40 μL/min in the SPE using the capillary columns, 15,24,26,27 the acceptable flow rate of 45 μL/min is sufficient for the coupling between the microcolumn SPE and CE in practice.…”

“…In addition to implementation of electric connection for CE, the interface should have the ability to exactly transfer nanoliters of fractions from SPE onto CE with minimized degradation of the efficiencies of SPE and CE. For such a purpose, a variety of interfaces have been designed, including such types as valve-loop, 7,8 T-split, 9,10 valve-loop-vial or T-piece, [11][12][13][14] two-leveled two cross, 15,16 flow-gating, 11,[17][18][19][20][21] and interfaces with integrated SPE. 22,23 With the first three types of interfaces, success of the coupling has been achieved to some extent, but some limitations have been recognized.…”

“…However, the position of the SPE outlet relative to the CE capillary is critical to the performance of the SPE-CE system, and contamination of the CE capillary from the SPE effluent has been observed. 15,16 For the interface with integrated SPE, as the SPE column is part of the CE system, some deleterious influences of the SPE sorbent may occur on the CE system during analysis. 22 Most of the aforementioned interfaces require relatively complicated switching procedures that may result in poor reproducibilities.…”

Determination of fluoroquinolones in blood by matrix solid‐phase dispersion extraction and CE

“…The major drawbacks in CE are the low sensitivity and low repeatability compared with HPLC. To overcome these drawbacks, liquid–liquid extraction (LLE) 11, 12 and SPE 13–15 are often introduced to improve the sensitivity.…”