Application of Supercritical Fluid Extraction in Quality Control of Chinese Medicines

Traditional Chinese medicine (TCMs), as an important branch of medicine, has been used in the treatment of various diseases in East Asia for thousands of years. However, due to the complexity of TCMs, the development of quality control methods has always been regarded as a challenging and important factor in their modernization and globalization. Among the procedures involved in the quality control of TCMs, extraction is the first and most critical step. Analysis of an improper treated sample may result in poor quality of analytical data. As a new green extraction technology, supercritical fluid extraction (SFE) has gained increasing interest due to its selective extraction, low operation cost, short processing time, and less impact on the environment, compared to that of most conventional extraction methods. The selectivity and yield of the target compounds can be adjusted by optimizing of the process parameters, especially the temperature, pressure, and modifiers based on method design. Following the extraction, an adequate evaluation based on the identification, quantity, and bioactive analysis of the compounds present in the extract is necessary for the quality control of TCMs. Phytochemical profiling tools such as GC, LC, SFC, and their online methods applied to identify and quantify these bioactive compounds are discussed. In this article, the basic principles, methods, instruments, and main characteristics and application of SFE in quality control of TCMs in the past five years are reviewed.