Vitamin A
(vye' ta min).
DEFINITION
Vitamin A contains a suitable form of retinol (C20H30O; vitamin A alcohol) and possesses vitamin A activity equivalent to NLT 95.0% of that declared on the label. It may consist of retinol or esters of retinol formed from edible fatty acids, principally acetic and palmitic acids. It may be diluted with edible oils; or it may be incorporated in solid, edible carriers, or excipients; and it may contain suitable antimicrobial agents, dispersants, and antioxidants.
IDENTIFICATION
•  A. Color Reaction with Antimony III
Sample solution: Equivalent to 6 µg/mL of retinol in chloroform
Analysis: To 1 mL of the Sample solution add 10 mL of antimony trichloride TS.
Acceptance criteria: A transient blue color appears at once.
•  B. Thin-Layer Chromatographic Identification Test
Standard solution: Dissolve the contents of 1 ampul of USP Vitamin A RS in chloroform to obtain 25.0 mL.
Sample solution for the liquid form of vitamin A: Dissolve a volume, equivalent to about 15,000 USP Units, in chloroform to obtain 10.0 mL of solution.
Sample solution for the solid form of vitamin A: Transfer a quantity, equivalent to about 15,000 USP Units, to a separator, add 75 mL of water, and shake vigorously for 1 min. Extract with 10.0 mL of chloroform by shaking for 1 min, and centrifuge to clarify the chloroform extract.
Chromatographic system 
Mode: TLC
Adsorbent: 0.25-mm layer of chromatographic silica gel mixture
Application volume 
Standard solution: 15 µL
Sample solution: 10 µL
Developing solvent system: A mixture of cyclohexane and ether (4:1)
Spray reagent: Phosphomolybdic acid TS
Analysis 
Samples: Standard solution and the appropriate Sample solution
Allow the solvent front to move a distance of 10 cm, remove the plate, and air-dry. Spray the plate with Spray reagent.
Acceptance criteria: The blue-green spot formed is indicative of the presence of retinol. The approximate RF values of the predominant spots, corresponding to the different forms of retinol, are 0.1 for the alcohol form, 0.45 for the acetate, and 0.7 for the palmitate.
ASSAY
•  Vitamin A Assay 571
Sample: Use a suitable quantity of vitamin A.
Analysis: Proceed as directed in the chapter.
Acceptance criteria: Equivalent to NLT 95.0% of the labeled amount of vitamin A activity
SPECIFIC TESTS
•  Absorbance Ratio
Sample: Use a suitable quantity of vitamin A.
Analysis: Proceed as directed for Vitamin A Assay 571, Chemical Method.
Acceptance criteria: The ratio of the corrected absorbance [A325] to the observed absorbance [A325] is NLT 0.85.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers, preferably under an atmosphere of an inert gas, protected from light.
•  Labeling: Label it to indicate the form in which the vitamin is present, and to indicate the presence of any antimicrobial agent, dispersant, antioxidant, or other added substance, and to indicate the vitamin A activity in terms of the equivalent amount of retinol, in mg/g. The vitamin A activity may be stated also in USP Units, on the basis that 1 USP Vitamin A Unit equals the biological activity of 0.3 µg of the all-trans isomer of retinol.
•  USP Reference Standards 11
USP Vitamin A RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/QuestionContactExpert Committee
MonographHuy T. Dinh, M.S.
Scientific Liaison
1-301-816-8594
(DS2010) Monographs - Dietary Supplements
Reference StandardsRS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 5029
Pharmacopeial Forum: Volume No. 29(6) Page 2004
Chromatographic Column— 
Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30.