Additional information is available at the end of the chapter http://dx.doi.org/10.5772/45955. Introduction Worldwide demand of herbal medicines has increased in recent years owing to rising interest in the health benefits. "mong with this, the quality control of plant extracts and plant-derived medicines is growing in importance to ensure their efficacy and safety. Effective quality control of the traditional Chinese medicines TCMM and plant crude extracts requires the rapid and sensitive methods for separation and quantification of bioactive compounds. Various methods have been employed for the separation and quantification of certain constituents in medicinal plants or herbal medicines. However, the current methods in use are not necessarily optimal approaches. For example, separation and quantification of glycyrrhi-zin GCC, the main active constituent in licorice Glycyrrhiza spp.., have been used gas chromatography , high performance liquid chromatography HPLCC and micellar trokinetic chromatography and so on [,,]. Commercial purification of GC typically progressed through several steps, including crystallization, column chromatography, and liquid partitioning. These current methods are not sufficiently approaches because of insufficient sensitivity and reproducibility, large consumption of organic solvent for extraction and analysis, and long analysis time. Immunoassay systems using monoclonal antibody M"bb against drugs and small molecular weight bioactive compounds have become an important tool for studies on receptor binding assays, enzyme assays, and quantitative and qualitative analytical techniques both in vivo and in vitro studies. "lthough immunoaffinity purification against higher molecule analyte such as peptides and proteins are widely used in the research and commercial ways, there are too few cases of immunoaffinity purification targeting a small molecule compound such as natural compounds. Our laboratory has prepared many kinds of M"bs against © 2012 Uto et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. naturally occurring bioactive compounds such as terpenoids [[-], alkaloids [[,,], saponins [[-], and phenolics [[[-], and developed several applications. One of the applications by using M"bs is immunoaffinity column conjugated with anti-natural compound-specific M"bs and work by specifically binding and removing the target compounds. We have been establishing several affinity columns against a kind of terpenoid, forskolin [[[], solasodine glyco-sides [[[], ginsenosides Rb [[[], and GC [[[]. "pplication of an immunoaffinity column to isolate and concentrate a natural compound may decrease the amount of solvent consumption and the number of purification steps, shorten analysis time, and simplify sample analysis compared to traditional cleanup technique...