The use in HPLC of short columns (3-7 cm in length) with conventional internal diameters (2-6 mm), packed with small particles (3- or 5- µm dp). Separation times in minutes, sometimes seconds are common.

Use of HPLC of short columns (1.5–7 cm) with conventional inner diameters (2–6 mm) packed with small particles (3- or 5-μm d_p). Separation times in the range of minutes, or even seconds, are common.