30 Escitalopram Oxalate 艾司西酞普兰USP标准

3094Erythromycin / Official Monographs USP 35

relevant USP Reference Standard; W is the quantity, in mg, of the remaining flasks add 2.0 mL of water. Allow to stand for 5 Erythromycin Stearate taken to prepare the Assay preparation;minutes with intermittent swirling. T o all flasks add 15.0 mL of and r U and r S2 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 and mix. Heat the flasks in a water bath at 60±0.5° for 5 minutes, Standard preparation 2, respectively. The per centage of er ythro-and allow to cool. Using a suitable spectrophotometer, deter-mycin B is not more than 12.0%; and the per centage of er yth-mine the absorbance of each solution, corrected for its blank romycin C is not more than 5.0%.solution, at the wavelength of maximum absorbance at about

236 nm. Determine the amount of C37H67NO13 dissolved from

the Test solution in comparison with the solution obtained from

the Working standard solution.

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

37H67NO13 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 T ab-equivalent of not less than 90.0 per cent and not lets in a capillar y-stoppered bottle in vacuum at 60° for 3

more than 120.0 per cent of the labeled amount hours: 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 RS

USP Erythromycin Stearate RS Escitalopram Oxalate

Identification—To a quantity of powdered T ablets add a vol-

ume of methanol sufficient to yield a solution containing the

equivalent of about 5 mg of er ythromycin per mL. Shake this

mixture by mechanical means for about 30 minutes. Centrifuge

a portion of this mixture, and use the clear supernatant as the

test solution. Prepare a Standard solution of USP Er ythromycin

Stearate RS in methanol containing about 8 mg per mL. Apply

separately 20 µL each of the test solution and the Standard

solution to a suitable thin-layer chromatographic plate (see

C20H21FN2O·C2H2O4414.43 Chromatography 〈621〉) coated with a 0.25-mm layer of chro-

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

DEFINITION

solvent front, and allow the solvent to evaporate. Spray the

Escitalopram Oxalate contains NL T 98.0% and NMT 102.0% of plate 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 R F values of the principal fluorescent spots obtained IDENTIFICATION

from the test solution correspond to those obtained from the•A

. I NFRARED A BSORPTION〈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 acid tion corresponds to that of the Standard solution, as obtained

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

the chromatograms, in which the er ythromycin appears as a

black-to-purple spot: the R F value of the principal spot obtained ASSAY

from the test solution corresponds to that obtained from the•P ROCEDURE

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 weighed Time Solution B Solution C Flow Rate quantity of USP Er ythromycin RS in methanol to obtain a solu-(min)(%)(%)(mL/min) tion containing about 14 mg per mL. Dilute quantitatively with

09551 water, and mix to obtain a solution having a known concentra-

3565351

tion of about 0.56 mg of USP Er ythromycin RS per mL.

4501001 Working standard solution—On the day of use, dilute 25.0

45.101002

mL of Stock standard solution with water to 50.0 mL, and mix.

6001002 Test solution—After 120 minutes, withdraw a portion of the

solution under test, filter, and dilute with Medium, if necessar y,60.19551

to obtain a solution having an estimated concentration of about689551

0.28 mg of er ythromycin per mL.

[N OTE—The gradient was established on an HPLC system Procedure—Transfer 5.0-mL portions of the Working standard

with a dwell volume of approximately 1.6 mL. The injec-solution to two 25-mL volumetric flasks, one of which ser ves as

tion time can be adjusted relative to the start of a run to

a working standard blank. Similarly, transfer 5.0-mL portions of

accommodate changes in dwell volume from one HPLC the Test solution to two 25-mL volumetric flasks, one of which

system to another to achieve the separation described.] serves as a blank for that Test solution. To each of the flasks

designated as a blank add 2.0 mL of 0.5 N sulfuric acid and to