USP Reference standards 
11
—
USP Thiethylperazine Maleate RS.
NOTE—Throughout the following procedures, protect test or assay specimens, the Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware.
pH 791—
Dissolve 100 mg in 100 mL of water, warming, if necessary, to effect solution: the pH of this solution is between 2.8 and 3.8.
Selenium 291—
The absorbance of the solution from the
Test Solution, prepared with 100 mg of Thiethylperazine Maleate and 100 mg of magnesium oxide, is not greater than one-half that from the
Standard Solution (0.003%).
Chromatographic purity—
[NOTE—Conduct this test promptly without exposure to daylight and with minimum exposure to artificial light.
]
Diluting solution
: a mixture of methanol and ammonium hydroxide (49:1).
Test solution—
Transfer 100 mg of Thiethylperazine Maleate, accurately weighed, to a 5-mL volumetric flask. Dissolve in and dilute with
Diluting solution to volume, and mix.
Standard solutions—
Dissolve an accurately weighed quantity of
USP Thiethylperazine Maleate RS in
Diluting solution, and dilute quantitatively, and stepwise if necessary, with
Diluting solution to obtain a solution having a known concentration of 20.0 mg per mL (
Standard solution A). Dilute appropriate portions of this solution quantitatively with
Diluting solution to obtain five
Standard solutions B to
F having known concentrations of 0.2, 0.1, 0.06, 0.04, and 0.02 mg per mL, respectively. The final concentrations of
Standard solutions B to
F represent 1%, 0.5%, 0.3%, 0.2%, and 0.1% concentration of
Standard solution A, respectively.
Application volume:
5 µL.
Developing solvent system:
a mixture of ether, cyclohexane, methanol, and ammonium hydroxide (25:10:5:1).
Procedure—
Apply equal spots of the
Test solution and
Standard solutions A to
F as directed in
Ordinary Impurities 466. Examine the plate under short- and long-wavelength UV light, then spray the plate with Dragendorff's TS, dry the plate with a stream of nitrogen, and then spray with
hydrogen peroxide TS: any secondary spot in the
Test solution is not more than 0.5%, and the sum of all secondary spots is not more than 2.0%.
Assay—
Dissolve about 250 mg of Thiethylperazine Maleate, accurately weighed, in 30 mL of glacial acetic acid, and warm on a steam bath to effect solution. Add 1 drop of
crystal violet TS, and titrate with 0.1 N perchloric acid VS to a blue-green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 31.59 mg of C
22H
29N
3S
2·2C
4H
4O
4.
;)
for 4 hours: it loses not more than 0.5% of its weight.