Natural products have served mankind as a source of medicine since — and even before — historical records began. Herbal extracts now play an important and growing role in disease prevention and therapy, and are used extensively as drugs and food additives.

Compared with synthetic chemical drug compounds, the composition of herbal extracts is far more complex. Consequently, their quality control is becoming an increasingly important issue. For example, by the European legislation (directive 2004/24/EC concerning "traditional herbal medicinal products") a more strict control on the quality and purity of these products is required. This is also the case by the State Drug Administration of China. It involves, for example, the creation of a type of monograph as a guideline to test the identity and quality.

Figure 1

Confusion can also occur due to language. For example, when translating from Chinese pin-yin terminology into western languages or when the same name is used in different regions for different parts of the plant, or even different species or genera.

An example of such a language confusion resulting in the mistaken use of a herb occurred in the beginning of the 1990s in Belgium. Stephania tetrandra, which is used in a herbal treatment against obesity, was exchanged with Aristolochia fangchi, a herb resulting in a severe nephropathy because of the presence of aristolochic acid. Confusion probably occurred because of the similarity in the pin-yin terminology of both plants: Feng Fangji vs. Guang Fangji, respectively.

The fingerprint chromatograms are also accepted by the World Health Organization (WHO) as an identification and qualification technique for medicinal herbs. There are two main phases of a fingerprint approach:

• The development of the fingerprint.
• The extraction of information.