Chlorhexidine Acetate Topical Solution
DEFINITION
Chlorhexidine Acetate Topical Solution contains NLT 90.0% and NMT 110.0% of the labeled amount of chlorhexidine acetate (C22H30Cl2N10·2C2H4O2).
IDENTIFICATION
• A.
The retention time of the major peak for chlorhexidine from the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
• B. Identification Tests—General, Acetate 
191
:
Meets the requirements of the lanthanum nitrate test
191:
Meets the requirements of the lanthanum nitrate test
Sample:
Evaporate or dilute a volume of Topical Solution containing the equivalent of about 5 mg of chlorhexidine acetate to about 5 mL.
ASSAY
• Procedure
Solution A:
Dissolve 27.6 g of monobasic sodium phosphate and 10 mL of triethylamine in 1.5 L of water. Adjust with phosphoric acid to a pH of 3.0, and dilute with water to 2000 mL. Prepare a mixture of the resulting solution and acetonitrile (70:30).
Solution B:
Acetonitrile
Mobile phase:
See the gradient table below.
| Time (min) |
Solution A (%) |
Solution B (%) |
|---|---|---|
| 0 | 100 | 0 |
| 9 | 100 | 0 |
| 10 | 45 | 55 |
| 15 | 45 | 55 |
| 16 | 100 | 0 |
| 21 | 100 | 0 |
System suitability solution:
50 µg/mL of USP Chlorhexidine Acetate RS and 1 µg/mL of USP p-Chloroaniline RS in Solution A
Standard solution:
40 µg/mL of USP Chlorhexidine Acetate RS in Solution A
Sample solution:
Nominally 40 µg/mL of chlorhexidine acetate from the Topical Solution, prepared as follows. Transfer an amount of Topical Solution, equivalent to 20 mg of chlorhexidine acetate, to a 100-mL volumetric flask, and dilute with methanol to volume. Further dilute a 10-mL portion of this solution with Solution A to 50 mL.
Chromatographic system
Mode:
LC
Detector:
UV 239 nm
Column:
4.6-mm × 25-cm; 5-µm packing L1
Column temperature:
40
Flow rate:
1.5 mL/min
Injection size:
50 µL
System suitability
Sample:
System suitability solution
[Note—The approximate relative retention times for chlorhexidine and p-chloroaniline are about 1.0 and 1.3, respectively. ]
Suitability requirements
Resolution:
NLT 3.0 between chlorhexidine and p-chloroaniline
Relative standard deviation:
NMT 2.0% for the chlorhexidine peak, NMT 5.0% for the p-chloroaniline peak
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C22H30Cl2N10·2C2H4O2 in the portion of Topical Solution taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak area of chlorhexidine from the Sample solution |
| rS | = | = peak area of chlorhexidine from the Standard solution |
| CS | = | = concentration of USP Chlorhexidine Acetate RS in the Standard solution (µg/mL) |
| CU | = | = nominal concentration of chlorhexidine acetate in the Sample solution (µg/mL) |
Acceptance criteria:
90.0%–110.0%
IMPURITIES
Organic Impurities
• Procedure: Limit of p-Chloroaniline
Solution A, Solution B, Mobile phase, System suitability solution, and Chromatographic system:
Proceed as directed in the Assay.
Standard solution:
1.0 µg/mL of USP p-Chloroaniline RS in Solution A
Sample solution:
Nominally 2.0 mg/mL of chlorhexidine acetate from the Topical Solution, prepared as follows. Transfer an amount of Topical Solution, equivalent to 200 mg of chlorhexidine acetate, to a 100-mL volumetric flask, and dilute with Solution A to volume.
Analysis
Samples:
Standard solution and Sample solution
Acceptance criteria:
The p-chloroaniline peak area from the Sample solution is NMT the p-chloroaniline peak area from the Standard solution (NMT 500 ppm, calculated with reference to the nominal content of chlorhexidine acetate).
SPECIFIC TESTS
• pH 791:
5.0–7.0
791:
5.0–7.0
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers, protected from light.
• Labeling:
Label it to indicate that it is for veterinary use only.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Morgan Puderbaugh, B.S.
Associate Scientific Liaison 1-301-998-6833 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2622
Pharmacopeial Forum: Volume No. 36(1) Page 87