» Elm is the dried inner bark of Ulmus rubra Muhlenberg (Ulmus fulva Michaux) (Fam. Ulmaceae).
Unground Elm Unground Elm occurs as broad, flat, oblong pieces from 1 to 4 mm in thickness. The outer surface is yellow-orange with some brown outer bark or cork layers attached; the inner surface, which is pale yellow, is marked faintly with striated phloem lines. The fracture is fibrous with projections of five bast bundles.
Powdered Elm Powdered Elm is weak yellowish orange and has a distinctive fenugreek-like odor. Bast fibers are numerous, very long, usually broken, up to 25 µm in diameter, thick-walled, unlignified or with only a thin outer sheath of the wall lignified; calcium oxalate prisms from 10 to 35 µm in length; starch grains spheroidal or polygonal, usually from 3 to 15 µm in diameter, occasionally up to 25 µm in length; and numerous mucilage fragments, frequently lamellated. Cork cells are few or absent.
Packaging and storage Preserve in well-closed containers, and store in a cool, dry place.
A: Macerate 1 g of finely powdered Elm with 40 mL of cold water for 1 hour: the mixture is of a thick mucilaginous consistency and yellowish brown in color.
B: Extract 1 g of Powdered Elm with 10 mL of 60% methanol on a water bath for about 15 minutes, cool, filter, and concentrate the filtrate to about 2.5 mL. Separately apply 20 µL of this solution and 20 µL of a standard solution containing 0.025% rutin in methanol to a thin-layer chromatographic plate coated with a 0.25-mm layer of chromatographic silica gel. Develop the chromatogram in a solvent system consisting of a mixture of ethyl acetate, water, anhydrous formic acid, and glacial acetic acid (100:27:11:11) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chromatographic chamber, and allow to air-dry. Spray the plate with a 1% solution of 2-aminoethyl diphenylborinate ester in methanol followed by a 5% solution of polyethylene glycol 4000 in alcohol, and examine the plate under UV light at 366 nm: the RF values of the principal spots relative to rutin are about 1.05 (blue) and 0.8 (orange).
Outer bark It contains not more than 2% of adhering outer bark.
Foreign organic matter 561: not more than 2%.
Loss on drying 731 Dry about 2 g of Elm, accurately weighed, in an oven at 105 to constant weight: it loses not more than 12% of its weight.
Total ash 561: not more than 10%, calculated on the dried basis.
Acid-insoluble ash 561: not more than 0.65%, calculated on the dried basis.