Internal standard solution,Standard preparation,Chromatographic system,and System suitability test— Proceed as directed in the Assayunder Terpin Hydrate.

Assay preparation— Pipet 10mLof Oral Solution into a separator,add 20mLof water and 10mLof 5Nsodium hydroxide,and extract with three 25-mLportions of chloroform,filtering each,successively,through cotton.Rinse the cotton with chloroform.To the combined rinse and extracts add 5.00mLof Internal standard solution,and mix.

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 terpin hydrate (C10H20O2·H2O)in each mLof the Oral Solution taken by the formula: in which 190.28and 172.27are the molecular weights of terpin hydrate (C10H20O2·H2O)and anhydrous terpin (C10H20O2),respectively;WSis the weight,in mg,of USP Terpin Hydrate RS,calculated on the anhydrous basis;and RUand RSare the area-ratios of terpin to biphenyl obtained from the chromatograms for the Assay preparationand the Standard preparation,respectively.