A vacuum-evaporation loop-type valve interface for comprehensive capillary liquid chromatography of NPLC × RPLC was developed and evaluated.Two identical storage loops were used for storing the effluents alternatively from the first dimension.All the solvent in the loops was evaporated under vacuum conditions, leaving the analytes on the inner wall of the loop.The mobile phase of the second dimension dissolves the analytes in the loop and injects them onto the second column, allowing an on-line solvent exchange of a selected fraction from the first dimension to the second dimension.A normal-phase liquid chromatographic (NPLC) column of a 600 × 0.25 mm I.D.filled with 5 μm CN phase was used as the first dimension, and a reversed-phase liquid chromatographic (RPLC) column of 50 × 0.53 mm I.D.packed with 5 μm C18 phase was used as the second dimension.We evaluated the interface by controlling the loop temperature either at 80 ℃ or at 25 ℃, and investigated the sample losses by using standard samples with different boiling points.The chromatographic resolution of analytes on the two dimensions was maintained at their optimal conditions by using the system.The performance of the comprehensive 2D-LC system was demonstrated by separation of a standards and real life environmental samples.