A: The IRabsorption spectrum of a thin film of it exhibits maxima only at the same wavelengths as that of a similar preparation of USP Dexpanthenol RS,except that there is an additional maximum at about 5.6µm due to pantolactone.

B: It responds to Identificationtest Bunder Dexpanthenol.

Test solution: 50mg per mL,in water.

Internal standard solution— Prepare a solution of 2,6-dimethylphenol in toluene to contain about 100mg per mL.

Standard solution 1— Transfer about 100mg of USP Pantolactone RS,accurately weighed,to a 10-mLvolumetric flask,add methylene chloride to volume,and mix.

Standard solution 2— Pipet 0.4mLof Standard solution 1into a suitable small vial.Evaporate the solvent by means of a steady stream of dry air,and add 50µL,accurately measured,of Internal standard solution.Add 1mLof a mixture of pyridine,hexamethyldisilazane,and trimethylchlorosilane (9:3:1),immediately insert the stopper,and shake vigorously for 30seconds.

Test solution— Transfer about 100mg of Preparation,accurately weighed,to a suitable small vial,and proceed as directed for Standard solution 2,beginning with “add 50µL,accurately measured,of Internal standard solution.”

Chromatographic system (see Chromatography á621ñ)—Under typical conditions,the gas chromatograph is equipped with a flame-ionization detector and contains a suitable column,1.8m ×2.0mm,packed with 5%liquid phase G2on support S1A.The column and injection port are maintained isothermally at 170and 180,respectively.Using a suitable carrier gas,adjust the flow rate so that the derivatized pantolactone elutes in about 4minutes.Chromatograph five injections of the Standard solution 2,and record the peak responses as directed under Procedure:the relative standard deviation of the peak response ratios (RS)of the five injections is not more than 2.0%.The retention time of the derivatized pantolactone is about 0.75relative to that of the derivatized internal standard.In a suitable chromatogram,the resolution factor between the two peaks is not less than 2.0.

Procedure— Inject about 0.5µLof Standard solution 2into the gas chromatograph,record the chromatogram to obtain not less than 40%of maximum recorder response,and measure the peak responses of the derivatized pantolactone and the derivatized internal standard.Similarly,inject about 0.5µLof the Test solution,record the chromatogram,and measure the peak responses of the corresponding components.Calculate the quantity,in mg,of pantolactone in the portion of Preparation taken by the formula: in which CSis the concentration,in mg per mL,of USP Pantolactone RSin Standard solution 1,and RUand RSare the ratios of the peak response due to the pantolactone to that due to the internal standard obtained from the Test solutionand the Standard solution 2,respectively.