Chromatographic purity—
Adsorbent:
0.25-mm layer of chromatographic silica gel mixture.
Glycerin solution—
Dilute an accurately measured volume of glycerin with methanol to obtain a solution having a concentration of about 0.25 mg per mL.
Test solution—
Dissolve an accurately weighed quantity of Dihydroxyacetone in methanol to obtain a solution containing about 50 mg per mL.
Standard solution—
Dissolve an accurately weighed quantity of
USP Dihydroxyacetone RS in methanol, and mix to obtain a solution having a known concentration of about 50 mg per mL.
Application volume:
1 µL.
Developing solvent system:
a mixture of acetone and water (19:1).
Procedure—
Proceed as directed for
Thin-Layer Chromatography under
Chromatography 
621
. Spray the plate with a mixture of toluene, a saturated solution of lead tetraacetate in glacial acetic acid, and a 1% solution of dichlorofluorescein in alcohol (190:5:1), and dry the plate for 5 minutes at 105
. Examine the plate under short-wavelength UV light, and compare the intensities of the glycerin spot observed in the chromatogram of the
Test solution with that of the principal spot in the chromatogram of the
Glycerin solution: the glycerin spot from the chromatogram of the
Test solution is not larger or more intense than the principal spot obtained from the
Glycerin solution (0.5%), and no other secondary spots are observed in the chromatogram of the
Test solution.
Limit of protein—
Dissolve 25 g of Dihydroxyacetone in 100 mL of water. Transfer 100 µL of this solution to a 5-mL volumetric flask, dilute with
brilliant blue G TS to volume, and mix. Determine the absorbance of this solution at about 595 nm with a suitable spectrophotometer, using 100 µL of water and 5 mL of
brilliant blue G TS as the blank: the absorbance of the test solution is not more than 0.400.
Assay—
Dissolve an accurately weighed quantity of about 0.1 g of Dihydroxyacetone in 20 mL of water, add 20 mL of 0.1 M periodic acid, and allow to stand at room temperature in the dark for 20 minutes. Add about 3 g of sodium bicarbonate, 20 mL of 0.6 M potassium iodide, and 3 mL of
starch TS, and titrate with 0.05 M sodium arsenite VS. Perform a blank titration, and make any necessary correction. Each mL of 0.05 M sodium arsenite is equivalent to 4.504 mg of C
3H
6O
3.
;)
