On-line large-volume electroextraction coupled to liquid chromatography-mass spectrometry to improve detection of peptides.

Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier.

Discovery of early-stage biomarkers for diabetic kidney disease using ms-based metabolomics (FinnDiane study).

Diabetic kidney disease (DKD) is a devastating complication that affects an estimated third of patients with type 1 diabetes mellitus (DM). There is no cure once the disease is diagnosed, but early treatment at a sub-clinical stage can prevent or at least halt the progression. DKD is clinically diagnosed as abnormally high urinary albumin excretion rate (AER).

Online capillary liquid-liquid electroextraction of peptides as fast pre-concentration prior to LC-MS.

In this research paper, we show that capillary electroextraction (cEE) is capable of fast online peptide concentration and that it can be coupled online to LC-MS to result in a fast and sensitive method. Electroextraction takes place when an electrical field is applied in a two-phase liquid-liquid system. Sample molecules in the organic phase migrate very fast into the aqueous phase and are concentrated in a small zone.

Use of large-volume sample stacking in on-line solid-phase extraction-capillary electrophoresis for improved sensitivity.

We present a new system for the sensitive analysis of cephalosporins by CE using both on-line SPE and large-volume sample stacking (LVSS). Sample volumes of 250 muL were loaded onto the SPE microcolumn which was then desorbed with 426 nL of ACN. The SPE elution plug was injected into the CE system via an in-line valve interface filling approximately 60% of the volume of the separation capillary.

Design and applications of coupled SPE-CE.

CE suffers from an inherent low concentration sensitivity. Analyte detection limits can be improved by combining CE with SPE. This paper presents an overview of coupled SPE-CE systems that have been reported in literature.