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
(See Titrimetry 
541
.)
541.)
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
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
, 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%
281:
NMT 0.1%
• Limit of Aminopropanol
Sample:
5 g of Preparation
Blank:
10 mL of water
Titrimetric system
(See Titrimetry 541.)
541.)
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
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
781S
Sample solution:
50 mg/mL in water
Acceptance criteria:
+27.5 to +30.0
to +30.0
• Refractive Index 831:
1.495–1.502, at 20
831:
1.495–1.502, at 20
• Water Determination, Method I 921:
NMT 1.0%
921:
NMT 1.0%
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Huy T. Dinh, M.S.
Scientific Liaison 1-301-816-8594 |
(DS2010) Monographs - Dietary Supplements |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2850