RESUMO
Separation of complex mixtures needs more resolving power. In two dimensional liquid chromatography (2D LC), the sample is subjected to two different separation conditions or mechanisms, which significantly increases the peak capacity,resolving power and reduces peak overlap. Meanwhile, 2D separation is more reliable for peak i-dentification from run to run than single-dimension chromatography, because two independent elution times are ob-tained for each peak. Among different 2D liquid chromatographic combinations/configurations, online comprehensive 2D-LC has appeared to be very attractive due to its high peak capacity, minimal sample loss, good reproducibility, and easy to automation, especially for separation of very complex samples. The present review discusses the theoreti-cal aspects and hardware configuration of online 2D-LC, particularly online comprehensive 2D-LC. It highlights its concept, features, advantages, applications and prospective in TCM quality Control analysis.