FORWARD DEGENERATE 4-WAVE-MIXING AS A DETECTION METHOD IN LIQUID SEPARATION SYSTEMS - IMPROVING DETECTION LIMITS BY MEANS OF A FABRY-PEROT-INTERFEROMETER
Gp. Hoornweg et al., FORWARD DEGENERATE 4-WAVE-MIXING AS A DETECTION METHOD IN LIQUID SEPARATION SYSTEMS - IMPROVING DETECTION LIMITS BY MEANS OF A FABRY-PEROT-INTERFEROMETER, Applied spectroscopy, 51(7), 1997, pp. 1008-1011
A simple, small, and low-resolution confocal Fabry-Perot interferomete
r (CFP) has been developed to improve the signal-to-noise ratio (S/N)
in forward degenerate four-wave mixing (F-D4WM) detection, coupled to
high-performance liquid chromatography (HPLC). Its appropriateness is
based on the difference in coherence between the F-D4WM signal and the
background stray light. A detailed description of the specially desig
ned CFP and its performance is presented. The improvement in S/N was c
alculated from the chromatographic peaks recorded after an HPLC separa
tion of 1- and 2-aminoanthraquinone. The concentration limit of detect
ion (LOD) was improved by a factor of 30; for 1-aminoanthraquinone it
was 2 x 10(-8) M injected (corresponding to about 3 x 10(-9) M in the
detector cell), which is quite favorable in view of its low molar exti
nction coefficient being 2000 M-1 cm(-1) at the utilized laser wavelen
gth (514.5 nm).