WHO published Quality control methods for medicinal plant materials in 1998 in order to support WHO Member States in establishing quality standards and specifications for herbal materials, within the overall context of quality assurance and control of herbal medicines. This is the updated edition of the 1998 publication, with an updated title.

The purpose of this updated edition remains unchanged from that of the first edition. It is to support the development of national standards based on local market conditions, with due regard to existing national legislation and national and regional norms. It describes a series of internationally harmonized tests for assessing the quality of herbal materials, including the determination of pesticide residues, arsenic and toxic heavy metals, microorganisms and aflatoxins.

A collection of recommended test procedures for assessing the identity, purity, and content of herbal materials, intended to assist national laboratories engaged in pharmaceutical quality control, the manual responds to the growing use of herbal medicines, the special quality problems they pose, and the corresponding need for international guidance on reliable methods for quality control. Where relevant, suitable test apparatuses are illustrated and explained.

The publication includes chapters that cover internationally harmonized procedures for preparing culture media, strains of microorganisms suitable for use in tests, specifications for adsorbents for use in thin-layer chromatography, and detailed descriptions of the reagents, test solutions, and volumetric solutions used in the recommended tests.

Recommended procedures - whether involving visual inspection or the use of thin-layer chromatography for the qualitative determination of impurities - should also prove useful to the pharmaceutical industry and pharmacists working with herbal materials.

In order to promote good practices and to provide general technical guidance in conducting the test methods described in this publication, WHO good practices for pharmaceutical quality control laboratories is annexed to this publication for easy reference. The scope of the good practice guidance includes pharmaceutical laboratories handling herbal medicines, and an example of a list of equipment for pharmacognosy/phytochemical laboratories is provided therein.

This new edition will continue to serve as key technical training material for national capacity-building in setting standards for herbal medicines. This publication is an example of the immediate response of WHO in the implementation of the resolution on Global strategy and plan of action on public health, innovation and intellectual property that was adopted by the Sixty-first World Health Assembly in 2008.