Embodiments in accordance with the present invention relate to packed-column nano-liquid chromatography (nano-LC) systems integrated on-chip, and methods for producing and using same. The microfabricated chip includes a column, frits/filters, an injector, and a detector, fabricated in a process compatible with those conventionally utilized to form integrated circuits. The column can be packed with supports for various different stationary phases to allow performance of different forms of nano-LC, including but not limited to reversed-phase, normal-phase, adsorption, size-exclusion, affinity, and ion chromatography. A cross-channel injector injects a nanolitre/picolitre-volume sample plug at the column inlet. An electrochemical/conductivity sensor integrated at the column outlet measures separation signals. A self-aligned channel-strengthening technique increases pressure rating of the microfluidic system, allowing it to withstand the high pressure normally used in high performance liquid chromatography (HPLC). On-chip sample injection, separation, and detection of mixture of anions in water is successfully demonstrated using ion-exchange nano-LC.