Chromium Picolinate contains NLT 98.0% and NMT 102.0% of chromium picolinate (C18H12N3O6Cr), calculated on the dried basis.
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.
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.
Mode: Atomic absorption spectrophotometry
Analytical wavelength: 357.9 nm
Lamp: Chromium hollow-cathode
Blank: Diluted nitric acid
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
Acceptance criteria: 98.0%102.0% on the dried basis
• Chloride and Sulfate, Chloride 221
Sample solution: Dissolve 30 mg of Chromium Picolinate in 3040 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 3040 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%).
• Loss on Drying 731: Dry a sample at 105 for 4 h: it loses NMT 4.0% of its weight.
• Packaging and Storage: Preserve in tight containers.
• USP Reference Standards 11
USP Chromium Picolinate RS
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USP35NF30 Page 1250