Palmitic Acid
C16H32O2 256.43
Hexadecanoic acid
[57-10-3].
(pal mit' ik as' id).
C16H32O2 256.43
Hexadecanoic acid
[57-10-3].DEFINITION
Palmitic Acid is a mixture of solid organic acids obtained from fats or oils of animal or vegetable origin. It contains NLT 92.0% of palmitic acid (C16H32O2) and NMT 6.0% of stearic acid (C18H36O2).
IDENTIFICATION
• A.
The retention time of the major peak for palmitic acid of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
ASSAY
• Procedure
Sample solution:
Proceed as directed for Test solution in Fats and Fixed Oils 
401
, Fatty Acid Composition.
401, Fatty Acid Composition.
Standard solution:
Prepare the Standard solution in the same manner as the Sample solution, using a mixture of 50 mg of USP Palmitic Acid RS and 50 mg of USP Stearic Acid RS instead of the substance to be examined.
Chromatographic system:
Prepare as directed in Fats and Fixed Oils 401, Fatty Acid Composition.
401, Fatty Acid Composition.
Injection size:
1 µL
System suitability
Sample:
Standard solution
[Note—The relative retention times for methyl palmitate and methyl stearate are 0.9 and 1.0, respectively. ]
Suitability requirements
Resolution:
NLT 3.0 between methyl stearate and methyl palmitate
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C16H32O2 in the portion of Palmitic Acid taken:
Result = (rU/rT) × 100
| rU | = | = peak response for methyl palmitate from the Sample solution |
| rT | = | = sum of the responses of all the peaks in the chromatogram except the solvent peak |
Similarly, calculate the percentage of C18H36O2 in the portion of Palmitic Acid taken:
Result = (rU/rT) × 100
| rU | = | = peak response for methyl stearate from the Sample solution |
| rT | = | = sum of the responses of all the peaks in the chromatogram except the solvent peak |
Acceptance criteria:
NLT 92.0% of palmitic acid (C16H32O2) and NMT 6.0% of stearic acid (C18H36O2)
IMPURITIES
• Heavy Metals, Method II 231:
NMT 10 ppm
231:
NMT 10 ppm
SPECIFIC TESTS
• Color:
Heat a sample of Palmitic Acid to 75
. The resulting liquid is not more intensely colored than a solution prepared by mixing 1.2 mL of ferric chloride CS and 0.3 mL of cobaltous chloride CS with 0.3 N hydrochloric acid to make 10 mL, and diluting 5 mL of this solution with 0.3 N hydrochloric acid to make 100 mL. Make the comparison by viewing the solutions downward in matched color-comparison tubes against a white surface (see Color and Achromicity 631).
. The resulting liquid is not more intensely colored than a solution prepared by mixing 1.2 mL of ferric chloride CS and 0.3 mL of cobaltous chloride CS with 0.3 N hydrochloric acid to make 10 mL, and diluting 5 mL of this solution with 0.3 N hydrochloric acid to make 100 mL. Make the comparison by viewing the solutions downward in matched color-comparison tubes against a white surface (see Color and Achromicity 631).
• Congealing Temperature 651:
60–66
651:
60–66
• Fats and Fixed Oils, Acid Value 401:
216–220, using 1 g
401:
216–220, using 1 g
• Fats and Fixed Oils, Iodine Value 401:
NMT 1. Proceed as directed in Method I, except use 35 mL of chloroform.
401:
NMT 1. Proceed as directed in Method I, except use 35 mL of chloroform.
• Mineral Acid
Analysis:
Shake 5 g of melted Palmitic Acid with an equal volume of hot water for 2 min. Cool, and filter.
Acceptance criteria:
The filtrate is not reddened by the addition of 1 drop of methyl orange TS.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers, and store at room temperature.
• Labeling:
Label it to indicate whether it is derived from animal or vegetable sources.
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1885
Pharmacopeial Forum: Volume No. 30(3) Page 987