Cavity ring-down spectroscopy for detection in liquid chromatography at UV wavelengths using standard cuvettes in a normal incidence geometry.
Liquid chromatography (LC) with cavity ring-down spectroscopy (CRDS) detection, using flow cuvettes (put under normal incidence inside the ring-down cavity), is demonstrated. Fresnel reflections are maintained within the capture range of a stable cavity of 4 cm length. This method circumvents the need for specific Brewster's angles and possible mirror degradation is avoided. The flow cuvettes are commercially available at low cost. At 355 nm (the frequency-tripled output of a Nd:YAG laser), the system surpasses the performance of conventional absorbance detectors; the baseline noise was 1.3 x 10(-5)AU and detection limits (injected concentrations) were between 40 and 80 nM for nitro-polyaromatic hydrocarbons with an extinction coefficient epsilon of 7.3-10.2 x 10(3)M(-1)cm(-1). The system was also tested at 273 nm, but in the deep UV the reflectivity of the currently best available mirrors (R>or=99.91%) is still too low to show a significant improvement as compared to conventional UV-vis detection.
van der Sneppen
L
L
Laser Centre, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
Ariese
F
F
Gooijer
C
C
Ubachs
W
W
D002853:Chromatography, Liquid / Q000295:instrumentation / Q000379:methods*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
D011084:Polycyclic Aromatic Hydrocarbons