A: Infrared Absorption á197Kñ:dried over a suitable desiccant for 4hours.

B: Add a few drops of sulfuric acid to a hot solution:the liquid becomes turbid and develops a strongly aromatic odor.

Internal standard solution— Dissolve a quantity of biphenyl in chloroform to obtain a solution containing about 20mg per mL.

Standard preparation— Transfer about 170mg of USP Terpin Hydrate RS,accurately weighed,to a 100-mLvolumetric flask,dissolve in 5mLof alcohol,add 5.00mLof Internal standard solution,dilute with chloroform to volume,and mix.

Assay preparation— Transfer about 170mg of Terpin Hydrate,accurately weighed,to a 100-mLvolumetric flask,and proceed as directed under Standard preparation,beginning with “dissolve in 5mLof alcohol.”

Chromatographic system— Under typical conditions,the gas chromatograph is equipped with a flame-ionization detector,and it contains a 3.5-mm ×1.2-m glass column packed with 6%G1on support S1A;the injection port and the detector temperatures are maintained at 260,and the column temperature at 120;and nitrogen is used as the carrier gas,at a flow rate necessary to yield approximate retention times of 7minutes for terpin and 11minutes for biphenyl.

System suitability test— Chromatograph the Standard preparation,and record the chromatograms as directed for Procedure:the resolution,R,between the terpin and biphenyl peaks is not less than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject about 1µLof the Standard preparationinto a suitable gas chromatograph,and record the chromatogram.Similarly,inject about 1µLof the Assay preparation,and record the chromatogram.Calculate the quantity,in mg,of C10H20O2in the portion of Terpin Hydrate taken by the formula: in which WSis the weight,in mg,of USP Terpin Hydrate RS,calculated on the anhydrous basis;and RUand RSare the area-ratios of terpin to the internal standard obtained from the chromatograms for the Assay preparationand the Standard preparation,respectively.