Pulsed UV Laser-Induced Stationary Capillary Vibration for Highly Sensitive and Direct Detection Of Capillary Electrophoresis

摘要

A stationary wave of the capillary vibration effect was successfully induced by a series of short laser pulses. This wave could be applied to highly sensitive detection of capillary electrophoresis as well as the already reported capillary vibration induced by an intensity-modulated CW laser (CVL effect). Generally, pulses with much shorter width than the period of the natural frequency of the vibrating system cannot induce a standing vibration. However, utilizing the time constant of CVL determined by heat dissipation time, we found conditions which could induce a stable stationary wave of the capillary by a series of nanosecond light pulses. We used the KrF excimer laser operated at 248 nm with a pulse width of 60 ns and output of ~10 μJ/pulse as the CVL excitation source and applied it to highly sensitive detection of nonderivatized amino acids at the femtomole level. The sensitivity was at least 2 orders of magnitude superior to that of a commercially available UV absorbance detector. This technique extends the CVL's spectral regions. For ex-ample, in the UV region, where many biological materials have significant absorption bands, this technique will extend analytical applications in capillary electrophoresis by eliminating the need for a derivatization process.