Macroscopic— Yellowish green, petiolate, usually 2 to 5 cm in length but sometimes up to 10 cm, ovate, deeply divided into five or occasionally seven segments, each with a coarsely crenate margin and obtuse apex; both surfaces downy and the mid-rib prominent on the lower surface.

Histology— Upper and lower epidermal cells with wavy anticlinical walls, striated cuticle and anomocytic stomata, more frequent on the lower epidermis; trichomes, more abundant on the lower epidermis, of two types; covering trichomes uniseriate with up to six small isodiametric basal cells and elongated, tapering apical cells, often at right angles to the axis of the basal cells; glandular trichomes slightly sunken, composed of a short, biseriate, two- or four-celled stalk and a biseriate head of four cells, around which the cuticle forms a bladder-like covering.

A: The retention time of the parthenolide peak in the chromatogram of the Test solution corresponds to that in the chromatogram of the Standard solution, as obtained in the test for Content of parthenolide.

B: Reduce about 10 g of Feverfew to a fine powder, and transfer about 1.0 g of the powder, accurately weighed, to a suitable flask. Add 20 mL of methanol, heat the flask over a water bath at 60 for 15 minutes, cool, and filter. Evaporate the filtrate under reduced pressure to dryness, and dissolve the residue in 2.0 mL of methanol. Separately apply 20 µL of this solution and 20 µL of a Standard solution of USP Parthenolide RS in methanol containing 1.0 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.5-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatograms in a solvent system consisting of a mixture of toluene and acetone (85:15) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chromatographic chamber, mark the solvent front, and allow it to air-dry. Spray the plate with a 0.5% solution of vanillin in a mixture of sulfuric acid and alcohol (8:2). After 5 minutes, examine the plate in daylight. A blue spot in the middle portion of the chromatogram of the test solution that corresponds in color and RF value to the principal spot obtained in the chromatogram of the Standard solution indicates the presence of parthenolide. The lower one-third of the chromatogram of the test solution may exhibit two pink spots, and the upper one-third may exhibit one pink spot.

C: To 1 g of finely powdered Feverfew add 10 mL of methanol, and heat on a water bath at 60 for about 15 minutes. Cool, and filter. Separately apply 20 µL of this solution and 20 µL of a Standard solution of USP Rutin RS in methanol containing 0.25 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of ethyl acetate, water, anhydrous formic acid, and glacial acetic acid (10:2.7:1.1:1.1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chromatographic chamber, and allow it to air-dry. Spray the plate with a 1% solution of 2-aminoethyl diphenylborinate in methanol followed by a 5% (w/v) solution of polyethylene glycol 4000 in alcohol, and examine the plate under UV light at 366 nm. Relative to the RF value of the principal spot from the Standard solution, the chromatogram of the test solution exhibits no blue spot at RF 1.1 (distinction from Roman chamomile), but exhibits a green spot at RF 2.3 (distinction from Matricaria) and colored spots at RF values indicated as follows: 1.5 (yellowish orange), 1.65 (yellowish green), 2.0 (greenish blue), and 2.25 (whitish blue).

Mobile phase— Prepare a filtered and degassed mixture of water and acetonitrile (55:45). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard solution— Dissolve an accurately weighed quantity of USP Parthenolide RS in methanol, and dilute quantitatively, and stepwise if necessary, with methanol to obtain a solution having a known concentration of about 0.04 mg per mL.

Test solution— Reduce about 100 g of Feverfew to a fine powder, and transfer about 1.0 g of the powder, accurately weighed, to a suitable flask. Add 100 mL of methanol, and heat on a water bath at 60 for 10 minutes. Remove the flask from the water bath, cool, and filter. Rinse the flask with three 5-mL portions of methanol, and filter, adding the rinsings to the filtrate. Transfer the residue left within the filter to the same flask, add 50 mL of methanol, and continue the rinse procedure as described above. Evaporate the combined filtrates under reduced pressure to dryness, and dissolve the residue in 20.0 mL of methanol. Transfer 10 mL of this solution to a 25-mL volumetric flask, dilute with methanol to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 2.0 mL per minute. Chromatograph the Standard solution and record the peak responses as directed for Procedure: the tailing factor for the parthenolide peak is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses of the major peaks. Calculate the percentage of parthenolide in the portion of Feverfew taken to prepare the Test solution by the formula: in which C is the concentration, in mg per mL, of USP Parthenolide RS in the Standard solution; W is the weight, in g, of Feverfew taken for the Test solution; and rU and rS are the areas of the parthenolide peak responses obtained from the Test solution and the Standard solution, respectively: not less than 0.2% is found.