Packaging and storage—
Preserve in tight, light-resistant containers.
USP Reference standards 
11
—
USP Mesoridazine Besylate RS.
NOTE—Throughout the following procedures, protect test or assay specimens, the USP Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware.
Identification—
B:
Ultraviolet Absorption 197U—
Solution:
10 µg per mL.
Medium:
methanol.
Absorptivities at 263 nm, calculated on the dried basis, do not differ by more than 3.0%.
pH 791:
between 4.2 and 5.7, in a freshly prepared solution (1 in 100).
Heavy metals, Method II 231:
0.002%.
Selenium 291—
The absorbance of the solution from the
Test Solution, prepared with 100 mg of Mesoridazine Besylate and 100 mg of magnesium oxide, is not greater than one-half that from the
Standard Solution (0.003%).
Ordinary impurities 466—
Test solution:
a solution in methanol having a known concentration of 14.1 mg per mL equivalent to 10 mg of mesoridazine per mL.
Standard solution:
methanol.
Eluant:
a mixture of chloroform, isopropyl alcohol, and ammonium hydroxide (87:12:1).
Visualization:
3, followed by spraying with 3% (v/v) aqueous hydrogen peroxide.
Application volume:
10 µL.
Limit:
3.0%.
Organic volatile impurities, Method I 467:
meets the requirements.
Assay—
Dissolve about 150 mg of Mesoridazine Besylate, accurately weighed, in 70 mL of acetic anhydride, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 27.24 mg of C21H26N2OS2·C6H6O3S.
Auxiliary Information—
Staff Liaison :
Ravi Ravichandran, Ph.D., Senior Scientist
Expert Committee : (MDPP05) Monograph Development-Psychiatrics and Psychoactives
USP29–NF24 Page 1357
Pharmacopeial Forum : Volume No. 30(4) Page 1262
Phone Number : 1-301-816-8330
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for 4 hours: it loses not more than 0.5% of its weight.