In general, a reference material is a highly characterized material which can be used as a standard in the testing and quality control of other materials. Applied to herbal products or dietary supplements, purified compounds (phytoconstituents) as well as well-characterized plant extracts and powders are commonly used as reference materials. The characterization of these botanical reference materials is a demanding task, and well-established reference materials (e.g. pure phytoconstituents) are in high demand.
Typically, only a very small amount of a reference standard is used as the basis for detection of the presence and quantity of the same compound in the material being tested. Despite a growing interest in dietary supplements by consumers, health care providers are often reluctant to promote the use of these natural products due to inaccurate labeling, adulteration, contamination, and drug interactions. Reference standards are, thus, instrumental to establish the integrity of botanical products and are the foundation for ensuring the quality of a dietary supplement or natural product.
According to the World Health Organization (WHO), "the general use of a reference substances should be considered as an integral part of a compliance-oriented monograph or test procedure used to demonstrate the identity, purity, and content of pharmaceutical substances and preparations". Reference materials are used to demonstrate the quality of a substance by comparing that substance to a standard reference material.
Exemplary uses of reference materials are: