Macroscopic— Yellowish green,petiolate,usually 2to 5cm in length but sometimes up to 10cm,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 solutioncorresponds to that in the chromatogram of the Standard solution,as obtained in the test for Content of parthenolide.

B: Reduce about 10g of Feverfew to a fine powder,and transfer about 1.0g of the powder,accurately weighed,to a suitable flask.Add 20mLof methanol,heat the flask over a water bath at 60for 15minutes,cool,and filter.Evaporate the filtrate under reduced pressure to dryness,and dissolve the residue in 2.0mLof methanol.Separately apply 20µLof this solution and 20µLof a Standard solution of USP Parthenolide RSin methanol containing 1.0mg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)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 5minutes,examine the plate in daylight.Ablue spot in the middle portion of the chromatogram of the test solution that corresponds in color and RFvalue 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 1g of finely powdered Feverfew add 10mLof methanol,and heat on a water bath at 60for about 15minutes.Cool,and filter.Separately apply 20µLof this solution and 20µLof a Standard solution of USP Rutin RSin methanol containing 0.25mg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)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 4000in alcohol,and examine the plate under UVlight at 366nm.Relative to the RFvalue of the principal spot from the Standard solution,the chromatogram of the test solution exhibits no blue spot at RF1.1(distinction from Roman chamomile),but exhibits a green spot at RF2.3(distinction from Matricaria)and colored spots at RFvalues 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 Suitabilityunder Chromatography á621ñ).

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

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

Chromatographic system (see Chromatography á621ñ)—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 2.0mLper minute.Chromatograph the Standard solutionand 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 10µL)of the Standard solutionand the Test solutioninto 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 solutionby the formula: in which Cis the concentration,in mg per mL,of USP Parthenolide RSin the Standard solution;Wis the weight,in g,of Feverfew taken for the Test solution;and rUand rSare the areas of the parthenolide peak responses obtained from the Test solutionand the Standard solution,respectively:not less than 0.2%is found.