Limit of cathinone hydrochloride—
Transfer 2.5 g to a 25-mL volumetric flask, add dilute hydrochloric acid (1 in 120) to volume, and mix. Concomitantly determine the absorbances of this solution and a Standard solution of
USP Cathinone Hydrochloride RS in the same medium having a known concentration of 100 µg per mL in 1-cm cells at the wavelength of maximum absorbance at about 285 nm, using dilute hydrochloric acid (1 in 120) as the blank: the absorbance of the test solution is not greater than that of the Standard solution. Not more than 0.10% is found.
Limit of amphetamine hydrochloride—
Mobile phase—
Prepare a filtered and degassed mixture of water, acetonitrile, phosphoric acid, and triethylamine (950:50:8:5). Make adjustments if necessary (see
System suitability under
Chromatography 
621
).
Amphetamine stock solution—
Dissolve an accurately weighed quantity of
USP Dextroamphetamine Sulfate RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 2.5 µg per mL.
Phenylpropanolamine stock solution—
Transfer about 2.5 g of Phenylpropanolamine Hydrochloride, accurately weighed, to a 10-mL volumetric flask, dilute with water to volume, and dissolve, using sonication if necessary.
Standard solution—
Transfer 4.0 mL of Phenylpropanolamine stock solution, accurately measured, to a 10-mL volumetric flask, add 4.0 mL of Amphetamine stock solution, dilute with water to volume, and mix to obtain a solution having known concentrations of about 100 mg per mL and 1 µg per mL, respectively.
Test solution—
Transfer about 4.0 mL of Phenylpropanolamine stock solution, accurately measured, to a 10-mL volumetric flask, dilute with water to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 206-nm detector and a 4.6-mm × 25-cm column that contains 5-µm, base-deactivated packing L1. The flow rate is about 1 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the relative retention times are 1.0 for phenylpropanolamine and 2.1 for amphetamine; the resolution,
R, between phenylpropanolamine and amphetamine is not less than 15; and the column efficiency is not less than 10,000 theoretical plates. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the relative standard deviation of the amphetamine peak for replicate injections is not more than 3.0%.
Procedure—
Separately inject equal volumes (about 5 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the responses at the locus of the amphetamine peak. Calculate the percentage of amphetamine hydrochloride in the portion of Phenylpropanolamine Hydrochloride taken by the formula:
0.2(171.67/368.49)(
CS / CU)[
rU /(
rS 
rU)]
in which 171.67 and 368.49 are the molecular weights of amphetamine hydrochloride and amphetamine sulfate, respectively;
CS is the concentration, in µg per mL, of
USP Dextroamphetamine Sulfate RS in the
Standard solution; CU is the concentration, in mg per mL, of Phenylpropanolamine Hydrochloride in the
Test solution; and
rU and
rS are the peak responses of amphetamine obtained from the
Test solution and the
Standard solution, respectively: not more than 0.001% is found.
Assay—
Dissolve about 500 mg of Phenylpropanolamine Hydrochloride, accurately weighed, in 50 mL of glacial acetic acid. Add 10 mL of
mercuric acetate TS and 2 drops of
crystal violet TS, and titrate with 0.1 N perchloric acid VS to a green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 18.77 mg of C
9H
13NO·HCl.
;)
-(1-aminoethyl)-, hydrochloride, (R*,S*)-, (±).
for 1 hour: the phenylpropanolamine so obtained melts between 101