Macroscopic— Ginger occurs in horizontal,laterally flattened,sympodially branching pieces.Whole rhizomes are 5to 15cm long,1.5to 6cm wide,and up to 2cm thick,sometimes split longitudinally;pale yellowish buff or light brown externally,longitudinally striated,somewhat fibrous;branches flattish,obovate,short,about 2cm long,each ending with a depressed stem scar;fracture,short with projecting fibers,or sometimes resinous;internally yellowish brown,showing a yellow endodermis separating the narrow cortex from the wide stele,and numerous yellowish points,secretion cells and numerous bigger greyish points,vascular bundles,scattered on the whole surface.The unscraped rhizome shows in addition an outer layer of dark brown cork.

Histology: Starch abundant in the thin-walled ground tissue,as flattened,ovate to subrectangular,transversely striated,simple granules,each with the hilum in a projection toward one end,mostly up to about 50µm long and up to about 25µm wide and 7µm thick.Oleoresin cells,with suberised cell walls and yellow contents,numerous in the ground tissue—pigment cells with dark,reddish brown contents occurring either singly in the ground tissue or in axial rows accompanying the vascular bundles.Irregularly shaped,thin-walled fibers with delicate transverse septa,yielding only slightly the reaction characteristic of lignin.Vessels with spiral or reticulate thickening in the scattered vascular bundles not yielding the reaction characteristic of lignin.In the unscraped ginger,varying amounts of cork,composed of thin-walled cells.Sclereids and calcium oxalate crystals absent.

A: Pulverize about 5g of Ginger.To about 1g of the pulverized Ginger add 5mLof dilute acetic acid,prepared by diluting 1part of glacial acetic acid with 1part of water,and shake for 15minutes.Filter,and add a few drops of ammonium oxalate TSto the filtrate:not more than a slight turbidity is produced.

B: Dissolve about 50mg of the residue obtained in the test for Alcohol-soluble extractivesin 25mLof water,and extract this solution with two 15-mLportions of ether.Combine the ether extracts,and evaporate in a porcelain dish.To the residue so obtained,add 5mLof sulfuric acid solution (7.5in 10.0)and about 5mg of vanillin.Allow to stand for 15minutes,and add an equal volume of water:the solution turns azure blue.

C: Thin-Layer Chromatographic Identification Test á201ñ—

1000(C/W)(rU/rS),

EB/100,

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile,dilute phosphoric acid (1in 1000),and methanol (55:44:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Capsaicin RSin methanol to obtain a solution having a known concentration of about 0.25mg per mL.

Test preparation— Transfer about 50mg,accurately weighed,of the residue (equivalent to about 9mg of gingerols)retained from the test for Alcohol-soluble extractivesto a 10-mLvolumetric flask,dissolve in and dilute with methanol to volume,and mix.

System suitability solution— Mix 1.0mLof the Standard preparationwith 1.0mLof the Test preparation.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 282-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 1.0mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 2.5%.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.8for 6-gingerol,1.0for capsaicin,1.51for 8-gingerol A,2.21for 8-gingerol B,2.46for 6-gingerdiol,2.60for 6-gingerdione,3.35for 10-gingerol,and 5.16for 8-gingerdione;and the resolution,R,between 6-gingerol and capsaicin is not less than 1.0.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Test preparationinto the chromatograph,and allow the Test preparationto elute for not less than seven times the retention time of capsaicin.Record the chromatograms,and measure all of the peak responses.Calculate the percentage of gingerols and gingerdiones,A,in the portion of the residue from the test for Alcohol-soluble extractivestaken for the Test preparationby the formula: in which Cis the concentration,in mg per mL,of USP Capsaicin RSin the Standard preparation;Wis the weight,in mg,of the residue from the test for Alcohol-soluble extractivestaken for the Test preparation;rUis the sum of the peak responses due to gingerols and gingerdiones as calculated above;and rSis the capsaicin peak response obtained from the Standard preparation:not less than 18%of gingerols and gingerdiones is found.Calculate the percentage of gingerols and gingerdiones in the Ginger rhizome by the formula: in which Eis the percentage of alcohol-soluble extractives obtained in the test for Alcohol-soluble extractives;and Ais as defined above:not less than 0.8%is found.