For whole drugs, macroscopic/sensory evaluation is usually enough for the drugs to be identified. Visual inspection in terms of shape, size, surface characteristics, colour, consistency, odour, taste, fracture and appearance of the cut surface of the drug provide the simplest and quickest means to establish its identity, purity and even quality. Comparison with the authentic drug will often reveal features not described in the requirements. Where needed measurements such as diameter of seeds and fruit samples are taken. General appearance of the sample itself will indicate whether it is likely to comply with standards. For example, percentage of clove stalks in cloves, ash in valerian, brittle broken leaves in leaf samples, horny fracture of starch-containing drugs, colour of the fractured surface (gentian) indicate improper processing during drug preparation.

Drug prices in the case of important drugs such as senna leaflets, senna pods, nutmeg, ginger and chamomile flowers are largely dependent on their macroscopic characters. Since these are judged subjectively and substitutes and adulterants may closely resemble the genuine material, it is often necessary to substantiate the findings by microscopy and physicochemical analysis.

Presence of Foreign Matter

Herbal materials should be entirely free from visible signs of contamination by moulds or insects and other contaminants including animal excreta. No abnormal odour, discolouration, slime or signs of deterioration should be detected. Since it is difficult to obtain plant materials in an entirely pure condition, pharmacopoeias contain statements as to the percentage of other parts of the plant or other organic matter which may be permitted. However, no poisonous, dangerous or otherwise harmful foreign matter or residue should be allowed. During storage products should be kept in a clean and hygienic place to avoid contamination. Special care should be taken to avoid formation of moulds, since they may produce aflatoxins. Any soil, stones, sand, dust and other foreign inorganic matter must be removed before herbal materials are cut or ground for testing.

Foreign matter is material consisting of parts of herbal material or those other materials not named within the limits specified for the concerned herbal material in the respective monographs. For examination of presence of foreign matter, weighed quantity ranging from 50–500 g based on the type of drug (roots, rhizomes, bark –500 g, leaves, flowers, seeds and fruit –250 g, cut herbal material – 50 g) is carefully spread in a thin layer. It is then examined using a magnifying lens (6x or10x) for sorting the foreign matter into groups which are then separated for weighing. The remaining sample is sifted through #250 sieve, dust being regarded as mineral admixture. The separated foreign matter is weighed and percent content calculated. Drugs containing appreciable quantities of potent foreign matter, animal excreta, insects or mould should be rejected even though the percentage of such substances are insufficient to cause rejection of the drug on the basis of percent foreign matter (as given in herbal pharmacopoeias). Detection of foreign matter in powdered drugs requires microscopic examination. When foreign matter consists of a chemical residue, TLC is often needed to detect the contaminant.