A remote flow cell for UV absorbance detection with capillary HPLC based on a single strand fiber optic

Combining capillary electrophoresis with mass spectrometry for applications in proteomics

Mass spectrometry (MS)-based proteomics is currently dominated by the analysis of peptides originating either from digestion of proteins separated by two-dimensional gel electrophoresis (2-DE) or from global digestion; the simple peptide mixtures obtained from digestion of gel-separated proteins do not usually require further separation, while the complex peptide mixtures obtained by global digestion are most frequently separated by chromatographic techniques. Capillary electrophoresis (CE) provides alternatives to 2-DE for protein separation and alternatives to chromatography for peptide separation. This review attempts to elucidate how the most promising CE modes, capillary zone electrophoresis (CZE) and capillary isoelectric focusing (CIEF), might best be applied to MS-based proteomics. CE-MS interfacing, mass analyzer performance, column coating to minimize analyte adsorption, and sample stacking for CZE are considered prior to examining numerous applications. Finally, multidimensional systems that incorporate CE techniques are examined; CZE often finds use as a fast, final dimension before ionization for MS, while CIEF, being an equilibrium technique, is well-suited to being the first dimension in automated fractionation systems.

A miniaturized fluorescence detector with a windowless flow cell using a light-emitting diode

A miniaturized fluorescence detector using a high-brightness light-emitting diode as an excitation source was constructed and evaluated. A windowless flow cell based on a commercial four-port cross fitting was designed to reduce the stray-light level and to eliminate the optical alignment. The observed detection limit for fluorescein was 26 nM in the continuous-flow mode. The error in the reproducibility of the responses was evaluated by the FIA method, and was found to be within 2% RSD.