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C11H16N2O3 224.26

2,4,6(1H,3H,5H)-Pyrimidinetrione, 5-(2-methylpropyl)-5-(2-propenyl)-.
5-Allyl-5-isobutylbarbituric acid [77-26-9].
» Butalbital contains not less than 98.0 percent and not more than 102.0 percent of C11H16N2O3, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
B: Ultraviolet Absorption 197U
Solution: 15 µg per mL.
Medium: 0.1 N sodium hydroxide.
Absorptivities at 246 nm, calculated on the dried basis, do not differ by more than 2.5%.
Melting range 741: between 138 and 141.
Loss on drying 731 Dry it in vacuum at room temperature to constant weight: it loses not more than 0.2% of its weight.
Residue on ignition 281: not more than 0.1%.
Chromatographic purity—
Chloroform-methanol— Mix equal volumes of chloroform and methanol.
Standard preparations— Dissolve a quantity of USP Butalbital RS in Chloroform-methanol to obtain a solution having a concentration of 40 mg per mL (Solution A). Dilute 1.0 mL of Solution A with Chloroform-methanol to 100 mL, and mix (Solution B); mix 5.0 mL of Solution B with 5.0 mL of Chloroform-methanol (Solution C); and mix 5.0 mL of Solution C with 5.0 mL of Chloroform-methanol (Solution D).
Test preparation— Dissolve a quantity of Butalbital in Chloroform-methanol to obtain a solution having a concentration of 40 mg per mL.
Procedure— In a suitable chromatographic chamber, arranged for thin-layer chromatography and lined with filter paper, place a volume of a developing solvent consisting of a mixture of acetone, dichloromethane, methanol, and ammonium hydroxide (50:30:10:10) sufficient to develop the chromatogram. Cover the chamber, and allow it to equilibrate for 30 minutes. Apply 10 µL each of the Test preparation and Solutions A, B, C, and D to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Develop the chromatogram until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and dry the plate in a current of air. Spray the plate with a reagent prepared by dissolving 5 g of potassium hydroxide in a mixture of 25 mL of water and 75 mL of alcohol. Allow the plate to dry in warm air for 10 minutes, and examine the chromatograms under UV light: the chromatograms show principal spots at about the same RF value; and the sum of the intensities of any secondary spots, if present in the chromatogram from the Test preparation, is not greater than 1% of that of the principal spot from Solution A. [note—The relative intensities of the principal spots from the Standard preparations are: Solution A, 1; Solution B, 0.01; Solution C, 0.005; and Solution D, 0.0025.]
Assay— Dissolve about 180 mg of Butalbital, accurately weighed, in a mixture of 25 mL of alcohol and 25 mL of sodium carbonate solution (3 in 100), and titrate with 0.1 N silver nitrate VS, determining the endpoint electrometrically, using a silver electrode, either with a suitable reference electrode containing a saturated aqueous solution of potassium nitrate, or a combination electrode in which the reference portion of the electrode contains a saturated aqueous solution of potassium nitrate. Each mL of 0.1 N silver nitrate is equivalent to 22.43 mg of C11H16N2O3.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ravi Ravichandran, Ph.D.
Senior Scientist
(MDPP05) Monograph Development-Psychiatrics and Psychoactives
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1730
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.