Capillary electrophoresis absorption detection using fiber-loop ring-down spectroscopy

Runkai Li

doi:10.1021/ac060289o

2006-07-20

PRE

Runkai Li

Hans‐Peter Loock *

Richard D. Oleschuk

DOI：10.1021/ac060289o

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摘要

En 中文

The application of phase-shift, fiber-loop, ring-down spectroscopy (PS-FLRDS) as an on-line detector for capillary electrophoresis (CE) of biomolecules is demonstrated. CE was conducted using a custom-designed capillary/fiber interface coupled to an absorption detector, which is based on the ring-down of an optical signal in a closed fiber waveguide loop. The ring-down times were obtained by measuring the phase difference between intensity modulated light entering and exiting the fiber loop. The incorporation of a microlens to enhance transmission through the sample gap led to an improvement of the sensitivity by up to 80% compared to the square-cut fiber and a reduction in the detection limit. The performance of the PS-FLRDS absorption technique as an online detector was characterized by flow injection through a capillary. Good repeatability and linear response were obtained, and the detection limit using the lensed fiber/ capillary interface system was determined to be alpha(min) = 1.6 cm(-1) for an absorption path of similar to 30 mu m. PS-FLRDS coupled to CE was also applied to the analysis of human serum albumin (HSA) by using a NIR dye as a noncovalent label. The excess free dye and the dye/protein complex were resolved. The labeling coefficient was determined to be similar to 6, and good repeatability of peak areas (RSD = 8.7%) was obtained for the analysis of HSA. Furthermore, an excellent linear response (R-2 > 0.99) was obtained between the peak areas and concentrations of HSA. The detection limit of labeled HSA was determined to be 1.67 mu M.

Keyword:

INDUCED FLUORESCENCE DETECTION

HUMAN SERUM-ALBUMIN

CAVITY RING

DIODE-LASER

SEPARATION

RESONATOR

FILMS