Chemical Behavior of Small Molecules and Polymers in the Precipitate From the Extract of the <i>Scutellaria baicalensis</i> – <i>Coptis chinensis</i> Pair: An HPLC‐ and FT‐IR‐Mediated Study

ABSTRACT The herbal pair of Scutellaria baicalensis roots (Hwang‐Geum) and Coptis chinensis rhizomes (Hwang‐Ryeon) is frequently used in Korean traditional medicine, and a precipitate is often formed during hot‐water extraction. This study investigated the chemical characteristics of the precipitate produced under various extraction conditions (temperature, time, and herbal ratio), measured using high‐performance liquid chromatography and Fourier transform infrared spectra (FT‐IR). Polymers were isolated from the precipitates of single or co‐decoctions of S. baicalensis and C. chinensis using a repeated methanol antisolvent method, and the chemical interactions among the components within the polymers were determined. Our findings indicated that flavonoid extraction benefits from a higher ratio of S. baicalensis , whereas alkaloid extraction is favored by a higher ratio of C. chinensis . The proportion of S. baicalensis more strongly influenced the extract and precipitate yields. Berberine was easily separated, whereas baicalin exhibited more complex behavior due to its strong interactions with the polymers. FT‐IR analysis confirmed the formation of a baicalin–berberine complex within the precipitate, which suggested increased hydrogen bonding with polysaccharide–polypeptide‐rich polymers. These results provide valuable insights for optimizing extraction processes and understanding precipitate formation in S. baicalensis and C. chinensis co‐decoctions, with specific relevance to herbal formulation and quality control.