Castor Oil Capsules
DEFINITION
Castor Oil Capsules contain NLT 90.0% and NMT 110.0% of the labeled amount of castor oil, calculated from the tests for Weight Variation and Specific Gravity.
IDENTIFICATION
•  A. Infrared Absorption 197S
Standard solution:  40 mg/mL of Castor Oil in chloroform
Sample solution:  40 mg/mL of the oil from Capsules in chloroform
Acceptance criteria:  Meet the requirements
PERFORMANCE TESTS
•  Uniformity of Dosage Units 905: Meet the requirements
SPECIFIC TESTS
•  Specific Gravity 841
Sample:  Capsule contents
Acceptance criteria:  0.957–0.961
•  Fats and Fixed Oils, Free Fatty Acids 401: The free fatty acids in 10 g require NMT 3.5 mL of 0.10 N sodium hydroxide for neutralization.
•  Fats and Fixed Oils, Hydroxyl Value 401
Free acid determination:  Determine the amount of free acid in the Capsule contents.
Sample:  10 g of Capsule contents
Titrimetric system 
Mode:  Direct titration
Titrant:  0.5 N alcoholic potassium hydroxide VS
Endpoint detection:  Visual
Analysis 1:  Transfer the Sample to a 250-mL conical flask, add 10 mL of pyridine that has been neutralized previously to phenolphthalein, and swirl to mix. Add 1 mL of phenolphthalein TS, and titrate with Titrant to a faint pink endpoint. Record the volume of Titrant consumed.
Hydroxyl value determination:  Determine the hydroxyl value of the Capsule contents.
Sample:  2 g from the Capsule contents
Blank:  5.0 mL of a freshly prepared mixture of 1 volume of acetic anhydride and 3 volumes of pyridine
Titrimetric system 
Mode:  Residual titration
Titrant:  0.5 N alcoholic potassium hydroxide VS
Endpoint detection:  Visual
Analysis 2:  Transfer the Sample to a glass-stoppered, 250-mL conical flask. Add 5.0 mL of a freshly prepared mixture of 1 volume of acetic anhydride and 3 volumes of pyridine, and swirl to mix. Connect the flask to a reflux condenser, and heat on a steam bath for 2 h. Add 10 mL of water through the condenser, swirl to mix, heat on a steam bath for an additional 10 min, and allow to cool to room temperature. Add through the condenser 15 mL of normal butyl alcohol that previously has been neutralized to phenolphthalein, remove the condenser, and wash the tip of the condenser and the sides of the flask with an additional 10 mL of neutralized normal butyl alcohol. Add 1 mL of phenolphthalein TS, and titrate with Titrant to a faint pink endpoint.
Calculate the hydroxyl value in the portion of Capsule contents taken:
Result = (Mr × N/W) × [B + (W × A/C) T]
Mr== milliequivalent weight of potassium hydroxide, 56.11 mg/mEq
N== actual normality of the Titrant
W== Sample weight for the hydroxyl determination (g)
B== Titrant volume consumed by the Blank (mL)
A== Titrant volume consumed by the Sample in the free acid determination (mL)
C== Sample weight for the free acid determination (g)
T== Titrant volume consumed by the Sample in the hydroxyl determination (mL)
Acceptance criteria:  160–168 in mg of KOH/g of Capsule content or hydroxyl value
•  Fats and Fixed Oils, Iodine Value 401
Sample:  Capsule contents
Acceptance criteria:  83–88
•  Fats and Fixed Oils, Saponification Value 401
Sample:  Capsule contents
Acceptance criteria:  176–182
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers, preferably at controlled room temperature.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Maged H. Sharaf, Ph.D.
Principal Scientific Liaison
1-301-816-8318
(DS2010) Monographs - Dietary Supplements
USP35–NF30 Page 2523