A: The IR absorption 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 5.6 µm due to pantolactone.

B: It responds to Identification test B under Dexpanthenol.

Test solution: 50 mg per mL, in water.

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

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

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

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

Chromatographic system (see Chromatography 621)—Under typical conditions, the gas chromatograph is equipped with a flame-ionization detector and contains a suitable column, 1.8 m × 2.0 mm, packed with 5% liquid phase G2 on support S1A. The column and injection port temperatures are maintained isothermally at 170 and 180, respectively. Using a suitable carrier gas, adjust the flow rate so that the derivatized pantolactone elutes in about 4 minutes. Chromatograph five injections of the Standard solution 2, and record the peak responses as directed for 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 0.75 relative 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 0.5 µL of Standard solution 2 into 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 0.5 µL of 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 CS is the concentration, in mg per mL, of USP Pantolactone RS in Standard solution 1; and RU and RS are the ratios of the peak response due to the pantolactone to that due to the internal standard obtained from the Test solution and the Standard solution 2, respectively.