Sample preparation is the crucial first step in
the analysis of herbs. In recent years there has been increasing
interest worldwide in the use of alternative/herbal
medicine for the prevention and treatment of various illnesses.
Currently, however, quality-related problems (lack
of consistency, safety, and efficacy) seem to be overshadowing
the potential genuine health benefits of various herbal
products. Thus, the development of “modern” sample-preparation
techniques with significant advantages over conventional
methods for the extraction and analysis of medicinal
plants is likely to play an important role in the
overall effort of ensuring and providing high-quality herbal
products to consumers worldwide. In this article, recent
developments and applications of modern sample-preparation
techniques for the extraction, clean-up, and concentration
of analytes from medicinal plants or herbal materials
are reviewed. These modern techniques include solidphase
microextraction, supercritical-fluid extraction, pressurized-
liquid extraction, microwave-assisted extraction,
solid-phase extraction, and surfactant-mediated extraction.