NEAR-FIELD THERMAL LENS DETECTOR FOR GRADIENT ELUTION LIQUID-CHROMATOGRAPHY

Reversed phase liquid chromatography (RP-LC) was applied to the separa tion of pesticides, The components were detected by a collinear near f ield thermal lens (NFTL) device. Two sample cells for different direct ions of liquid flow and interaction lengths were applied. Additionally a transversal near field thermal lensing device was used. A continuou s wave argon ion laser was taken as excitation light source at a wavel ength of 364 nm. The sensitivity of the NFTL devices were compared wit h a conventional UV-detector at the same wavelength. The limits of det ection (LOD) for the pesticides with the isocratic separation is one o rder of magnitude better for the collinear NFTL than for the UV-detect or. Not only isocratic but also gradient elutions were performed. Smal l changes of the eluent composition were obtained with linear gradient s and large changes with step wise gradients. Using the gradient separ ation technique, the detection limits of the collinear NFTL are 2-3 ti mes better than for the UV-detector. (C) 1997 Elsevier Science B.V.