Comparison of ultraviolet-laser induced and conventional fluorescence detection in conventional-size liquid chromatography of natively fluorescent analytes

✍ Scribed by R.J. van de Nesse; G.Ph. Hoornweb; C. Gooijer; U.A.Th. Brinkman; N.H. Velthorst; B. Law

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 992 KB
• Volume: 281
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)85195-p

✦ Synopsis

The characteristics of laser-induced fluorescence (LIF) detection and state-of-the-art conventional fluorescence (CF) detection in the UV region below 300 nm in conventional-size column liquid chromatography are compared. An argon-ion laser system is used to provide four laser lines, i.e. 257 and 293 nm obtained by frequency-doubling of visible light and the UV lines at 334 and 352 mn. Light intensities inside the detector cell were measured by means of actinometry. Flicker noise, especially important for LIF detection was suppressed by simultaneously monitoring the laser light and ratioing sample and reference signals. On-line removal of fluorescent impurities in the eluent by means of a precolumn fried with carbon material resulted in a three-fold reduction of the background signal for LIF detection with 2.57-nm excitation. It is shown that LIF detection at 257.nm is more suitable than LIF at 293,334 and 352 nm, not only for some pharmaceutical compounds that can only be excited below 300 nm, but also for polyaromatic hydrocarbons that absorb at wavelengths longer than 300 nm. Compared with CF detection at optimum excitation and emission settings, the detection limits obtained with the LIF system were improved typically by 5 to lo-fold.