Dexpanthenol Preparation
DEFINITION
Dexpanthenol Preparation contains NLT 94.5% and NMT 98.5% of dexpanthenol (C9H19NO4), and NLT 2.7% and NMT 4.2% of pantolactone, both calculated on the anhydrous basis.
IDENTIFICATION
•  A. The IR absorption spectrum of a thin film of Preparation 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 5.6 µm due to pantolactone.
•  B.
Sample solution: 100 mg/mL of Preparation
Analysis: To 1 mL of the Sample solution add 5 mL of 1 N sodium hydroxide and 1 drop of cupric sulfate TS, and shake vigorously.
Acceptance criteria: A deep blue color develops.
COMPOSITION
•  Content of Dexpanthenol
0.1 M potassium biphthalate: Transfer 20.42 g of potassium biphthalate into a 1000-mL volumetric flask, and add sufficient glacial acetic acid to dissolve. If necessary, warm the mixture on a steam bath to achieve complete solution, observing precautions against absorption of moisture. Cool to room temperature, and dilute with glacial acetic acid to volume.
Sample: 400 mg of Preparation
Blank: Proceed as directed in the Analysis, omitting the Sample.
Titrimetric system 
Mode: Residual titration
Titrant: 0.1 N perchloric acid VS
Back-titrant: 0.1 M potassium biphthalate
Endpoint detection: Visual
Analysis: Transfer the Sample to a 300-mL flask fitted to a reflux condenser by means of a standard-taper glass joint, add 50.0 mL of Titrant, and reflux for 5 h. Cool, observing precautions to prevent atmospheric moisture from entering the condenser, and rinse the condenser with glacial acetic acid, collecting the rinsings in the flask. To the flask add 5 drops of crystal violet TS, and titrate with the Back-titrant to a blue-green endpoint. Perform the Blank determination.
Calculate the percentage of dexpanthenol (C9H19NO4) in the Sample taken:
Result = {[(VB VS) × M × F]/W} × 100
VB== Back-titrant volume consumed by the Blank (mL)
VS== Back-titrant volume consumed by the Sample (mL)
M== actual molarity of the Back-titrant (mM/mL)
F== equivalency factor, 205.3 mg/mM
W== weight of the Sample (mg)
Acceptance criteria: 94.5%–98.5% on the anhydrous basis
•   Content of Pantolactone
Internal standard solution: 100 mg/mL of 2,6-dimethylphenol in toluene
Standard stock solution: 10 mg/mL of USP Pantolactone RS in methylene chloride
Standard solution: Pipet 0.4 mL of Standard stock solution into a suitable small vial. Evaporate the solvent by means of a steady stream of dry air, and add 50.0 µL of Internal standard solution. Add 1 mL of a mixture of pyridine, hexamethyldisilazane, and trimethylchlorosilane (9:3:1), immediately close the vial, and shake vigorously for 30 s.
Sample solution: Transfer 100 mg of Preparation to a suitable small vial, and proceed as directed for the Standard solution, beginning with “add 50.0 µL of Internal standard solution”.
Chromatographic system 
Mode: GC
Detector: Flame ionization
Column: 2.0-mm × 1.8-m, packed with 5% liquid phase G2 on support S1A
Temperature 
Column: 170, isothermal
Injector: 180
Flow rate: Using a suitable carrier gas, adjust the flow rate so that the derivatized pantolactone elutes in 4 min.
Injection size: 0.5 µL
System suitability 
Sample: Standard solution
[Note—The retention times of the derivatized pantolactone and derivatized internal standard are 0.75 and 1.0, respectively. ]
Suitability requirements 
Resolution: NLT 2.0 between the derivatized pantolactone and derivatized internal standard
Relative standard deviation: NMT 2.0% for the ratios of the derivatized pantolactone peak response to the derivatized internal standard peak response
Analysis 
Samples: Standard solution and Sample solution
Calculate the percentage of pantolactone in the portion of Preparation taken:
Result = (RU/RS) × (V/W) × CS) × 100
RU== internal standard ratio (peak response of derivatized pantolactone/peak response of derivatized internal standard) from the Sample solution
RS== internal standard ratio (peak response of derivatized pantolactone/peak response of derivatized internal standard) from the Standard solution
V== volume of the Standard stock solution taken to prepare the Standard solution, 0.4 mL
W== weight of Preparation taken to prepare the Sample solution (mg)
CS== concentration of USP Pantolactone RS in the Standard stock solution (mg/mL)
Acceptance criteria: 2.7%–4.2% on the anhydrous basis
IMPURITIES
•  Residue on Ignition 281: NMT 0.1%
•  Limit of Aminopropanol
Sample: 5 g of Preparation
Blank: 10 mL of water
Titrimetric system 
Mode: Direct titration
Titrant: 0.1 N sulfuric acid VS
Endpoint detection: Visual
Analysis: Dissolve the Sample in 10 mL of water, and add bromothymol blue TS. Titrate with the Titrant to a yellow endpoint. Perform the Blank determination.
Calculate the percentage of aminopropanol in the Sample taken:
Result = {[(VS VB) × N × F]/W} × 100
VS== Titrant volume consumed by the Sample (mL)
VB== Titrant volume consumed by the Blank (mL)
N== actual normality of the Titrant (mEq/mL)
F== equivalency factor, 75.11 mg/mEq
W== Sample weight (mg)
Acceptance criteria: NMT 1.0%
SPECIFIC TESTS
•  Optical Rotation, Specific Rotation 781S
Sample solution: 50 mg/mL in water
Acceptance criteria: +27.5 to +30.0
•  Refractive Index 831: 1.495–1.502, at 20
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers.
•  USP Reference Standards 11
USP Dexpanthenol RS Click to View Structure
USP Pantolactone RS
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/QuestionContactExpert Committee
MonographHuy T. Dinh, M.S.
Scientific Liaison
1-301-816-8594
(DS2010) Monographs - Dietary Supplements
Reference StandardsRS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 2850
Chromatographic Column— 
Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30.