Botanical Reference Materials

Reference materials are an essential part of conducting botanical authentication activities. Different types of reference materials are available for different requirements. See section on Reference Material Definitions below.

Reference Material Suppliers

The following AHPA members supply botanical reference materials of various types and, in some cases, purified reference substances.

• Alkemists Laboratories now introduces Composite Reference Botanicals™ custom blends of verified botanicals from multiple sources. A Certificate of Analysis includes a high-resolution Digital Photo Microscopy Image and Digital HPTLC Images.
• American Herbal Pharmacopoeia has archived more than 100 authentic botanical reference materials to use in the development of internal quality control specifications. The identity and purity of these standards have been confirmed through botanical, macroscopic, microscopic, HPTLC, and/or specific chemical methods of analyses.
• Botanical Liaisons’ botanical reference materials include a voucher specimen, a representative sample of the plant, often with an inflorescence, flower, pressed and preserved on archival paper. The label on the specimen informs the viewer of the date and location of the harvest of the voucher and can be tracked back to the collector.
• Chromadex offers a growing product line of Botanical Reference Materials of freeze dried and ground plant material whose certificates show an HP-TLC test method, profile image, and may also include macro and microscopic images.
• PhytoLab provides purified reference substances, which are important for the many HPTLC methods used for botanical identification.
• US Pharmacopeia Reference Standards are highly-characterized physical specimens used in testing by pharmaceutical and related industries to help ensure the identity, strength, quality, and purity of medicines (drugs, biologics, and excipients), dietary supplements, and food ingredients.

Reference Material Definitions

The National Institute of Standards and Technology (NIST) defines reference materials as follows:

Reference Material (RM)

Material, sufficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement process:

1. RM is a generic term.
2. Properties can be quantitative or qualitative, e.g. identity of substances or species.
3. Uses may include the calibration of a measurement system, assessment of a measurement procedure, assigning values to other materials, and quality control.
4. A single RM cannot be used for both calibration and validation of results in the same measurement procedure.
5. International Vocabulary of Metrology – Basic and General Concepts and Associated Terms has an analogous definition (VIM - ISO/IEC Guide 99:2007, 5.13), but restricts the term "measurement" to apply to quantitative values and not to qualitative properties. However, Note 3 of ISO/IEC Guide 99:2007, 5.13, specifically includes the concept of qualitative attributes, called "nominal properties".

(ISO Guide 30:1992/Amd 1:2008)

Certified Reference Material (CRM)

Reference material characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability:

1. The concept of value includes qualitative attributes such as identity or sequence. Uncertainties for such attributes may be expressed as probabilities.
2. Metrologically valid procedures for the production and certification of reference materials are given in, among others, ISO Guides 34 and 35.
3. ISO Guide 31 gives guidance on the contents of certificates.
4. VIM has an analogous definition (ISO/IEC Guide 99:2007, 5.14).

(ISO Guide 30:1992/Amd 1:2008)

Reference Material Certificate

Document accompanying a certified reference material stating one or more property values and their uncertainties, and confirming that the necessary procedures have been carried out to ensure their validity and traceability. (ISO Guide 30: 1992)

More about NIST

NIST provides a limited number of botanical reference materials (see http://nist.gov/srm/ for pricing and ordering information) and conducts a Dietary Supplement Analysis Quality Assurance Program. Suggestions for additional NIST botanical reference materials for this program and industry in general should be directed to Melissa Phillips (melissa.phillips@nist.gov).