Identification—
B:
Thin-Layer Chromatographic Identification Test 
201
—
Test solution—
Dissolve 10 mg of it in 1 mL of methanol, add 1 drop of ammonium hydroxide, and mix.
Application volume:
1 µL.
Developing solvent system:
methylene chloride, methanol, and ammonium hydroxide (90:14:1), in a saturated chamber.
Procedure—
Allow the plate to air-dry in a hood. Expose the dry plate for 30 minutes to short-wavelength UV light, then examine under long-wavelength UV light: the size, intensity, and RF value of the principal spot in the chromatogram obtained from the Test solution correspond to those characteristics of the principal spot in the chromatogram obtained from the Standard solution.
D:
To 10 mg of it add 3 drops of sulfuric acid. Mix, and add 50 mg of ammonium vanadate: a violet color is produced (differentiation from strychnine, which produces a red color). Add 1 mL of water: no color change occurs.
Chromatographic purity—
Use the chromatogram of the
Assay preparation obtained as directed in the
Assay. Calculate the percentage of each impurity in the portion of Yohimbine Hydrochloride taken by the formula:
100(ri / rs),
in which
ri is the response of the individual impurity; and
rs is the sum of all the responses in the chromatogram: not more than 1.0% of any individual impurity is found, and the sum of all the impurities found is not more than 2.0%.
Assay—
Mobile phase—
Prepare a mixture of water, dibasic sodium phosphate dihydrate solution (11.88 g per L), and monobasic potassium phosphate solution (9.08 g per L) (355:100:50). Add 4 g of sodium dodecyl sulfate, and mix. Add 285 mL of acetonitrile, and mix. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Quantitatively dissolve an accurately weighed quantity of
USP Yohimbine Hydrochloride RS in methanol to obtain a solution having a known concentration of about 0.2 mg per mL.
Assay preparation—
Transfer about 50 mg of Yohimbine Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dilute with methanol to volume, and mix. Transfer 10.0 mL of this solution to a 25-mL volumetric flask, dilute with methanol to volume, and mix.
System suitability solution—
Quantitatively dilute an accurately measured volume of the
Standard preparation with methanol to obtain a solution having a concentration of 0.40 µg of
USP Yohimbine Hydrochloride RS per mL.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 229-nm detector and a 4-mm × 12.5-cm column that contains 4-µm packing L7. The flow rate is about 2 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the main yohimbine peak gives a measurable response. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the tailing factor is not more than 2.5; and the relative standard deviation for replicate injections is not more than 1%.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in mg, of C
21H
26N
2O
3·HCl in the portion of Yohimbine Hydrochloride taken by the formula:
250C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Yohimbine Hydrochloride RS in the
Standard preparation; and
rU and
rS are the yohimbine peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
-Hydroxy-20-
-carboxylic acid, methyl ester, hydrochloride
and +105