Chromium Picolinate, chemical structure, molecular formula, Reference Standards

Chromium Picolinate

C18H12N3O6Cr 418.31

Chromium Tripicolinate.

»Chromium Picolinate contains not less than 98.0percent and not more than 102.0percent of C18H12N3O6Cr,calculated on the dried basis.

Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Chromium Picolinate RS.

Identification—

A: Infrared Absorption á197Mñ.

B: To 5mLof a solution (1in 250)in a test tube add 1mLof 5Nsodium hydroxide and 10drops of 30%hydrogen peroxide,and heat gently for about 2minutes:a yellow color develops.

Loss on drying á731ñ— Dry it at 105

for 4hours:it loses not more than 4.0%of its weight.

Chloride á221ñ— Dissolve 30mg of Chromium Picolinate in 30to 40mLof water,and heat to 70

.Cool overnight,and filter to remove the precipitate.Add 1mLeach of nitric acid and silver nitrate TS,and add sufficient water to make 50mL.Mix,and allow to stand for 5minutes,protected from direct sunlight:any turbidity formed is not greater than that produced in a similarly treated control solution containing 0.25mLof 0.002Nhydrochloric acid (0.06%).

Sulfate á221ñ— Dissolve 100mg of Chromium Picolinate in 30to 40mLof water,and heat to 90

.Cool overnight,and filter to remove the precipitate.Add 1mLof 3Nhydrochloric acid,3mLof barium chloride TS,and sufficient water to make 50mL.Mix,and allow to stand for 10minutes:any turbidity formed is not greater than that produced in a similarly treated control solution containing 0.2mLof 0.02Nsulfuric acid (0.2%).

Assay—

Standard stock solution— Transfer about 0.283g of potassium dichromate,previously dried at 120

for 4hours and accurately weighed,to a 1000-mLvolumetric flask,dissolve in and dilute with water to volume to obtain a solution having a known concentration of about 100µg of chromium per mL,and mix.Store in a polyethylene bottle.

Standard preparations— Separately transfer 1.0mLand 2.0mLof the Standard stock solutionto 100-mLvolumetric flasks,and transfer 1.5mLand 2.0mLof the Standard stock solutionto separate 50-mLvolumetric flasks.Add 1.0mLof nitric acid to each flask,dilute the contents of each flask with water to volume,and mix.These Standard preparationscontain 1.0,2.0,3.0,and 4.0µg of chromium per mL,respectively.

Assay preparation— Transfer about 200mg of Chromium Picolinate,accurately weighed,to a 500-mLvolumetric flask,and add 25mLof water.Slowly add 10mLof nitric acid,and boil for 10minutes with constant swirling.Cool the solution,dilute with water to volume,and mix.Filter a portion of the solution,and transfer 5mLof the filtrate to a 100-mLvolumetric flask.Add 1mLof nitric acid,dilute with water to volume,and mix.

Procedure— Concomitantly determine the absorbances of the Standard preparationsand the Assay preparationat the chromium emission wavelength of 357.9nm,with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering á851ñ)equipped with a chromium hollow-cathode lamp and an air–acetylene flame,using diluted nitric acid as the blank.Plot the absorbances of the Standard preparationsversus chromium concentration,in µg per mL,and draw the straight line best fitting the four plotted points.From the graph so obtained,determine the chromium concentration,in µg per mL,in the Assay preparation.Calculate the quantity,in mg,of C18H12N3O6Cr in the portion of Chromium Picolinate taken by the formula:

(418.31/51.996)(10C),

in which Cis the concentration,in µg per mL,of chromium in the Assay preparation;418.31is the molecular weight of chromium picolinate;and 51.996is the atomic weight of chromium.

Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist

Expert Committee:(DSN)Dietary Supplements:Non-Botanicals

USP28–NF23Page 2070

Phone Number:1-301-816-8389