Supercritical fluid extraction in herbal and natural product studies - a practical review.

Due to increasingly stringent environmental regulations, supercritical fluid extraction (SFE) has gained wide acceptance in recent years as an alternative to conventional solvent extraction for separation of organic compounds in many analytical and industrial processes. In the past decade, SFE has been applied successfully to the extraction of a variety of organic compounds from herbs and other plants. This review article presents the practical aspects of SFE applications in sample preparation, selection of modifiers, collection methods, on-line coupling techniques, means for avoiding mechanical problems, and approaches to optimization of SFE conditions. SFE can also be used to clean up pesticides from herb medicines. SFE processes can be modeled to acquire useful information for better understanding of the extraction, mechanisms and optimization of the extraction procedures. With increasing public interest in natural products, SFE may become a standard extraction technique for studying herbal, food and agricultural samples.