Chromium Picolinate
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C18H12N3O6Cr 418.31
Chromium Tripicolinate     [14639-25-9].
DEFINITION
Chromium Picolinate contains NLT 98.0% and NMT 102.0% of chromium picolinate (C18H12N3O6Cr), calculated on the dried basis.
IDENTIFICATION
•  B.
Sample solution:  4 mg/mL
Analysis:  To 5 mL of the Sample solution add 1 mL of 5 N sodium hydroxide and 10 drops of 30% hydrogen peroxide, and heat gently for 2 min.
Acceptance criteria:  A yellow color develops.
ASSAY
•  Procedure
Standard stock solution:  100 µg/mL of chromium. Transfer 0.283 g of potassium dichromate, previously dried at 120 for 4 h, to a 1000-mL volumetric flask, and dilute with water to volume. Store in a polyethylene bottle.
Standard solutions:  1.0, 2.0, 3.0, and 4.0 µg/mL of chromium. Separately transfer 1.0 and 2.0 mL of the Standard stock solution to 100-mL volumetric flasks, and transfer 1.5 and 2.0 mL of the Standard stock solution to separate 50-mL volumetric flasks. Add 1.0 mL of nitric acid to each flask, and dilute the contents of each flask with water to volume.
Sample solution:  Transfer 200 mg of Chromium Picolinate to a 100-mL beaker, and add 25 mL of water. Slowly add 10 mL of nitric acid, and boil for 10 min with constant swirling. Cool the solution, quantitatively transfer to a 500-mL volumetric flask, and dilute with water to volume. Filter a portion of the solution, and transfer 5.0 mL of the filtrate to a 100-mL volumetric flask. Add 1 mL of nitric acid, and dilute with water to volume.
Instrumental conditions 
Mode:  Atomic absorption spectrophotometry
Analytical wavelength:  357.9 nm
Lamp:  Chromium hollow-cathode
Flame:  Air–acetylene
Blank:  Diluted nitric acid
Analysis 
Samples:  Standard solutions and Sample solution
Determine the absorbances of the Standard solutions and the Sample solution. Plot the absorbances of the Standard solutions versus the chromium concentration, in µg/mL, and draw the straight line best fitting the four plotted points. From the graph so obtained, determine the chromium concentration, in µg/mL, in the Sample solution.
Calculate the percentage of chromium picolinate (C18H12N3O6Cr) in the portion of Chromium Picolinate taken:
Result = (CCr/CU) × (Mr/Ar) × 100
CCr== concentration of chromium in the Sample solution, obtained from the graph (µg/mL)
CU== concentration of Chromium Picolinate in the Sample solution (µg/mL)
Mr== molecular weight of chromium picolinate, 418.31
Ar== atomic weight of chromium, 51.996
Acceptance criteria:  98.0%–102.0% on the dried basis
IMPURITIES
•  Chloride and Sulfate, Chloride 221
Sample solution:  Dissolve 30 mg of Chromium Picolinate in 30–40 mL of water, and heat to 70. Cool overnight, and filter to remove the precipitate.
Analysis:  Add 1 mL each of nitric acid and silver nitrate TS, and add sufficient water to make 50 mL. Mix, and allow to stand for 5 min, protected from direct sunlight.
Acceptance criteria:  Any turbidity formed is NMT that produced in a similarly treated control solution containing 0.25 mL of 0.002 N hydrochloric acid (NMT 0.06%).
•  Chloride and Sulfate, Sulfate 221
Sample solution:  Dissolve 100 mg of Chromium Picolinate in 30–40 mL of water, and heat to 90. Cool overnight, and filter to remove the precipitate.
Analysis:  Add 1 mL of 3 N hydrochloric acid, 3 mL of barium chloride TS, and sufficient water to make 50 mL. Mix, and allow to stand for 10 min.
Acceptance criteria:  Any turbidity formed is NMT that produced in a similarly treated control solution containing 0.2 mL of 0.02 N sulfuric acid (NMT 0.2%).
SPECIFIC TESTS
•  Loss on Drying 731: Dry a sample at 105 for 4 h: it loses NMT 4.0% of its weight.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers.
•  USP Reference Standards 11
USP Chromium Picolinate RS
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Huy T. Dinh, M.S.
Scientific Liaison
1-301-816-8594
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