Transient isotachophoresis in on‐line solid phase extraction capillary electrophoresis time‐of‐flight‐mass spectrometry for peptide analysis in human plasma

Abstract

In this study, we evaluated the combination of transient isotachophoresis with on-line solid-phase extraction capillary electrophoresis time-of-flight mass spectrometry (SPE-tITP-CE-TOF-MS) to improve sensitivity of peptide analysis, using several opioid peptides as model compounds. First, standard solutions were analyzed in order to establish the tITP-CE methodology using UV and TOF-MS detection. The volume and composition of the leading and terminating electrolytes (i.e. LE and TE) for an efficient tITP were investigated to obtain optimum detection sensitivity and electrophoretic separation. In the best cases, LODs in tITP-CE-TOF-MS were tenfold better than those obtained in CE-TOF-MS (i.e. 5 versus 50 ng/mL). Afterwards, the tITP-CE-TOF-MS methodology was adapted to perform SPE-tITP-CE-TOF-MS. Repeatability, linearity and LODs were investigated and compared to the values obtained by SPE-CE-TOF-MS. Furthermore, human plasma samples fortified with the opioid peptides were analyzed in order to show the potential of SPE-tITP-CE-TOF-MS for peptide analysis in biological fluids. The LODs attained in standard solutions and plasma samples for some of the studied peptides (i.e. 0.01 and 0.1 ng/mL, respectively) were tenfold better than those obtained in SPE-CE-TOF-MS, proving the enhanced sensitivity that could be achieved when both on-line preconcentration approaches were combined together.

Improving the Comprehensiveness and Sensitivity of Sheathless Capillary Electrophoresis–Tandem Mass Spectrometry for Proteomic Analysis

“…27-31 When used in conjunction with tITP, further sensitivity gains have been shown. 32, 33 In the work described here, a SPME cartridge was employed to both concentrate samples and perform sequential elution to improve comprehensiveness prior to tITP-CE-MS/MS using the high sensitivity porous sprayer. We optimized critical SPME elution conditions and evaluated the sensitivity of the sheathless SPME-tITP-CE-MS/MS platform for analysis of a moderately complex proteomic mixture by comparison to both conventional nLC-MS/MS results over the same analysis time and CE without SPME-tITP using direct sample injections.…”

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2010–2012)

“…They immobilised polyclonal antibody against Endomorphin 1 and 2 (End1 and End2) through carbohydrate moieties to hydrazide commercial silica particles. The LODs of End1 and End2 standard mixtures were as low as 1 μg/L, but 100‐fold higher than those obtained in their previous work using tITP . Limited amount of IA sorbent contained in the lab‐made microcartridges, as well as its low immunoreactive surface area were claimed to affect the LODs.…”

Simulation and visualization of velocity fields in simple electrokinetic devices

“…Obviously, many of the newer capillary and microchip electrophoresis designs use altered injection interfaces, but the classical design is still an extremely common format. This general format is used in gradient moving boundary electrophoresis, 1, 2 stacking and supercharging, 3-5 transient isotachophoresis, [6][7][8][9] and electrophoretic exclusion. [10][11][12][13] Defining and analyzing the forces within the interfacial region can be performed rather trivially for fundamental equations (e.g.…”