ตำรายาของประเทศไทย
Thai Pharmacopoeia
สำนักยาและวัตถุเสพติด กรมวิทยาศาสตร์การแพทย์ กระทรวงสาธารณสุข
Bureau of Drug and Narcotic, Department of Medical Sciences, Ministry of Public Health7.2 FOREIGN MATTER
Vegetable drugs should be free from moulds, insects and other animal contamination.
Foreign matter is material consisting of any or all of the following:
1. Foreign organs: matter coming from the source plant but not defined as the drug.
2. Foreign elements: matter not coming from the source plant and of either vegetable or mineral origin.
Method
Weigh 100 to 500 g of the substance being examined or the quantity specified in the monograph and spread it in a thin layer. Separate the foreign matter by hand as completely as possible, weigh it and calculate the percentage present.