http://whqlibdoc.who.int/hq/1992/WHO_PHARM_92.559_rev.1.pdf

It presents units of measurement and their abbreviations, powder fineness and sieve size, and information on sampling, determination of foreign matter, visual examination and inpection by microscopy, thin-layer chromatography, determination of ash, extractable matter, water and volatile matter, volatile oils, bitterness value, haemolytic activity, tannings, swelling and foaming indexes, pesticide residues, arsenic and heavy metals, and microorganisms, and radioactive contamination. Document in pdf format; Acrobat Reader required.