(dex'' troe am fet' a meen sul' fate).
Benzeneethanamine, -methyl-, (S)-, sulfate (2:1).
(+)--Methylphenethylamine sulfate (2:1) [51-63-8].
» Dextroamphetamine Sulfate, the dextrorotatory isomer of amphetamine sulfate, contains not less than 98.0 percent and not more than 102.0 percent of (C9H13N)2·H2SO4, calculated on the dried basis.
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
USP Dextroamphetamine Related Compound A RS
C9H12O 136.20 [CAS-14898-87-4].
USP Dextroamphetamine Related Compound B RS
C9H10O 134.18 [CAS-103-79-7].
B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Specific rotation 781S: between +20 and +23.5.
Test solution: 40 mg per mL, in water.
pH 791: between 5.0 and 6.0, in a solution (1 in 20).
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Solution A, Solution B, Mobile phase, Resolution solution, and Chromatographic system Prepare as directed in the Assay.
Standard solution Use the Standard preparation.
Test solution Use the Assay preparation.
Procedure Inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, and record the chromatograms. Identify the impurities based on the relative retention times given in Table 1, and measure the peak responses. Calculate the percentage of each dextroamphetamine related compound in the portion of Dextroamphetamine Sulfate taken by the formula:
100(CS / CU)(rU /rS)(1/F)in which CS and CU are the concentrations, in mg per mL, of dextroamphetamine sulfate in the Standard solution and the Test solution, respectively; rU is the peak area of each impurity obtained from the Test solution; rS is the peak area of dextroamphetamine obtained from the Standard solution; and F is the relative response factor for each of the impurities relative to dextroamphetamine.
Solution A Add 5.0 mL of trifluoroacetic acid to 900 mL of water; adjust with ammonium hydroxide to a pH of 2.2±0.1; then add 100 mL of acetonitrile. Mix well, and degas.
Solution B Use degassed acetonitrile.
Mobile phase Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Dextroamphetamine Sulfate RS in a suitable volumetric flask, and dilute quantitatively with Solution A to obtain a solution having a known concentration of about 2.0 mg per mL.
Resolution solution Transfer about 40 mL of the Standard preparation to a 50-mL volumetric flask. Using a microliter syringe, add 1 µL each of USP Dextroamphetamine Related Compound A RS and USP Dextroamphetamine Related Compound B RS. Dilute with Standard preparation to volume.
Assay preparation Dissolve an accurately weighed quantity of Dextroamphetamine Sulfate in a suitable volumetric flask, and dilute quantitatively with Solution A to obtain a solution having a known concentration of about 2.0 mg per mL.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 257-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L1. The flow rate is about 1.5 mL per minute. The column is maintained at 40. The chromatograph is programmed as follows, and data is collected for 30 minutes.
Procedure Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the dextroamphetamine peak. Calculate the quantity, in percent of (C9H13N)2·H2SO4, in the portion of Dextroamphetamine Sulfate taken by the formula:
100(CS / CU)(rU / rS)in which CS and CU are the concentrations of dextroamphetamine sulfate, in mg per mL, of the Standard preparation and the Assay preparation, respectively; and rU and rS are the peak responses for dextroamphetamine sulfate in the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 2858Pharmacopeial Forum: Volume No. 34(4) Page 921