30 Escitalopram Oxalate 艾司西酞普兰USP标准

3094Erythromycin / Official MonographsUSP 35relevant USP Reference Standard; W is the quantity, in mg, ofthe remaining flasks add 2.0 mL of water. Allow to stand for 5Erythromycin Stearate taken to prepare the Assay preparation;minutes with intermittent swirling. To all flasks add 15.0 mL ofand rU and rS2 are the peak responses of the relevant analyte in0.25 N sodium hydroxide, dilute with Medium to volume, and

the chromatograms obtained from the Assay preparation andmix. Heat the flasks in a water bath at 60±0.5° for 5 minutes,Standard preparation 2, respectively. The percentage of erythro-and allow to cool. Using a suitable spectrophotometer, deter-mycin B is not more than 12.0%; and the percentage of eryth-mine the absorbance of each solution, corrected for its blankromycin C is not more than 5.0%.solution, at the wavelength of maximum absorbance at about236 nm. Determine the amount of C37H67NO13 dissolved from

the Test solution in comparison with the solution obtained fromthe Working standard solution.

Tolerances—Not less than 75% (Q) of the labeled amount ofErythromycin Stearate Tablets

C37H67NO13 is dissolved in 120 minutes.

Uniformity of dosage units 〈905〉: meet the requirements.» Erythromycin Stearate Tablets contain the

Loss on drying 〈731〉—Dry about 100 mg of powdered Tab-equivalent of not less than 90.0 percent and not

lets in a capillary-stoppered bottle in vacuum at 60° for 3more than 120.0 percent of the labeled amounthours: it loses not more than 5.0% of its weight.

of erythromycin (C37H67NO13).Assay—Proceed with Tablets as directed in the Assay under

Erythromycin Tablets.Packaging and storage—Preserve in tight containers.

USP Reference standards 〈11〉—USP Erythromycin RSUSP Erythromycin Stearate RSEscitalopram Oxalate

Identification—To a quantity of powdered Tablets add a vol-ume of methanol sufficient to yield a solution containing theequivalent of about 5 mg of erythromycin per mL. Shake thismixture by mechanical means for about 30 minutes. Centrifugea portion of this mixture, and use the clear supernatant as thetest solution. Prepare a Standard solution of USP ErythromycinStearate RS in methanol containing about 8 mg per mL. Applyseparately 20 µL each of the test solution and the Standardsolution to a suitable thin-layer chromatographic plate (seeC20H21FN2O·C2H2O4414.43Chromatography 〈621〉) coated with a 0.25-mm layer of chro-

S-(+)-5-Isobenzofurancarbonitrile, 1-[3-(dimethylamino)propyl]-matographic silica gel mixture, and allow to dry. Place the plate

1-(4-fluorophenyl)-1,3-dihydro-, oxalate; in an unlined chromatographic chamber, and develop the chro-

S-(+)-1-[3-(Dimethylamino)propyl]-1-(p-fluorophenyl)-5-matograms in a solvent system consisting of a mixture of meth-

phthalancarbonitrile oxalate [219861-08-2].anol and chloroform (85:15) until the solvent front has moved

about 9 cm. Remove the plate from the chamber, mark theDEFINITIONsolvent front, and allow the solvent to evaporate. Spray the

Escitalopram Oxalate contains NLT 98.0% and NMT 102.0% ofplate with a methanolic solution of 2′,7′-dichlorofluorescein (1

C20H21FN2O·C2H2O4, calculated on the anhydrous basis.

in 500), and examine the plate under long-wavelength UV

light: the RF values of the principal fluorescent spots obtained

IDENTIFICATION

from the test solution correspond to those obtained from the•A. INFRARED ABSORPTION 〈197K〉

Standard solution. Then spray the plate with a mixture of dehy-•B. The retention time of the major peak of the Sample solu-

drated alcohol, p-methoxybenzaldehyde, and sulfuric acidtion corresponds to that of the Standard solution, as obtained

(90:5:5). Heat the plate at 100° for 10 minutes, and examinein the Assay.

the chromatograms, in which the erythromycin appears as a

black-to-purple spot: the RF value of the principal spot obtained

ASSAY

from the test solution corresponds to that obtained from the•PROCEDURE

Standard solution.Solution A: 3.4 g/L of monobasic potassium phosphate in

Dissolution 〈711〉—water. Adjust with phosphoric acid or sodium hydroxide so-lution to a pH of 3.0 prior to final dilution.Medium: 0.05 M pH 6.8 phosphate buffer (see under Solu-

Solution B: Acetonitrile and Solution A (1:9)tions in the section Reagents, Indicators, and Solutions); 900 mL.

Solution C: Acetonitrile and Solution A (13:7)Apparatus 2: 100 rpm.

Mobile phase: See the gradient table below.

Time: 120 minutes.

Stock standard solution—Dissolve an accurately weighedTimeSolution BSolution CFlow Ratequantity of USP Erythromycin RS in methanol to obtain a solu-