Hydroxypropyl Cellulose Ocular System
Hydroxypropyl Cellulose Ocular System contains NLT 85.0% and NMT 115.0% of the labeled amount of Hydroxypropyl Cellulose. It contains no other substance. It is sterile.
•  Infrared Absorption
Sample solution:  A 10-mg/mL solution in methanol, based on the labeled amount of Hydroxypropyl Cellulose. Evaporate 2 drops of the solution on a silver chloride plate so that it forms a thin film.
Acceptance criteria:  The infrared absorption spectrum of the film exhibits maxima only at the same wavelengths as that of a similar preparation of USP Hydroxypropyl Cellulose RS.
•  Procedure
Standard stock solution:  0.25 mg/mL of USP Hydroxypropyl Cellulose RS prepared as follows: Weigh 25 mg of USP Hydroxypropyl Cellulose RS into a 100-mL volumetric flask. Dissolve in 80 mL of water. Mix well by agitating on a mechanical shaker until completely dissolved. Add one drop of methanol to dispel the foam and dilute with water to volume. [Note—Stirring overnight before diluting to volume is recommended. ]
Standard solution:  0.05 mg/mL of hydroxypropyl cellulose in water, from Standard stock solution
Sample stock solution:  0.25 mg/mL of hydroxypropyl cellulose prepared using the same procedure as the Standard stock solution
Sample solution:  0.05 mg/mL of hydroxypropyl cellulose in water, from Sample stock solution
Spectrometric conditions 
Mode:  UV-Vis
Analytical wavelength:  620 nm
Cell length:  1.0 cm, quartz
Samples:  Standard solution and Sample solution
Separately pipet 2 mL of the Standard solution, the Sample solution, and water, to provide a blank, into individual 50-mL centrifuge tubes. Add to each tube, 6.0 mL of a 0.5 mg/mL solution of anthrone in sulfuric acid, and mix on a vortex mixer. Let the centrifuge tubes cool for approximately 40 min and remix. Concomitantly determine the absorbances of the Standard solution and the Sample solution. [Note—Prepare anthrone in sulfuric acid solution just before use in low-actinic glassware, and mix well before adding to the tube. Use it within 12 h of preparation. Avoid contact between the glassware and the paper products during analysis; the cellulose in the paper will react with the sulfuric acid and alter the results. ]
Calculate the percentage of hydroxypropyl cellulose in the Ocular System:
Result = (AU/AS) × (CS/CU) × 100
AU== absorbance of the Sample solution
AS== absorbance of the Standard solution
CS== concentration of the Standard solution (mg/mL)
CU== nominal concentration of hydroxypropyl cellulose in the Sample solution (mg/mL)
Acceptance criteria:  85.0%–115.0%
•  Weight Variation
Analysis:  Determine the weight of each of a sufficient number of Systems.
Acceptance criteria:  NMT 1 out of 20 Systems varies more than 25% from the average or, failing that, NMT 6 out of 60 (including the original 20) vary more than 25% (but none more than 35%) from the average weight.
•  Sterility Tests 71: Meets the requirements
•  Packaging and Storage: Preserve in single-dose containers, at a temperature not exceeding 30.
•  USP Reference Standards 11
USP Hydroxypropyl Cellulose RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
Senior Scientific Liaison
(SM32010) Monographs - Small Molecules 3
71 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
USP35–NF30 Page 3456
Pharmacopeial Forum: Volume No. 35(4) Page 852