» Omeprazole contains not less than 98.0 percent and not more than 102.0 percent of C17H19N3O3S, calculated on the dried basis.
Packaging and storage Preserve in tight containers and store in a cold place, protected from moisture.
A: The RF value of the principal spot observed in the chromatogram of the Identification solution corresponds to that of the principal spot observed in the chromatogram of the Standard solution containing 0.15 mg of USP Omeprazole RS per mL, obtained as directed in the test for Chromatographic purity, Method 1.
Completeness of solution 641: meets the requirements, a solution in methylene chloride containing 20 mg per mL being used.
Color of solution Determine the absorbance of the solution prepared for the Completeness of solution test at 440 nm, in 1-cm cells, using methylene chloride as the blank: the absorbance is not greater than 0.10.
Loss on drying 731 Dry it in vacuum at 60 for 4 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.1%.
Heavy metals, Method II 231: 0.002%.
Solvent Prepare a mixture of dichloromethane and methanol (1:1).
Standard solutions Dissolve an accurately weighed quantity of USP Omeprazole RS in Solvent, and mix to obtain Standard solution A having a known concentration of about 0.5 mg per mL. Dilute this solution quantitatively with Solvent to obtain Standard solution B and Standard solution C having known concentrations of about 0.15 mg per mL and 0.05 mg per mL, respectively.
Test solution Prepare a solution of Omeprazole in Solvent containing 50 mg per mL.
Identification solution Dilute a volume of the Test solution quantitatively with Solvent to obtain a solution containing 0.25 mg per mL.
Procedure Separately apply 10 µL of the Test solution, the Identification solution, and each of the Standard solutions to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of ammonia-saturated dichloromethane, dichloromethane, and isopropyl alcohol (2:2:1) until the solvent front has moved about three-fourths of the length of the plate. [notePrepare ammonia-saturated dichloromethane as follows. Shake 100 mL of dichloromethane with 30 mL of ammonium hydroxide in a separatory funnel, allow the layers to separate, and use the lower layer.] Remove the plate from the developing chamber, mark the solvent front, allow the solvent to evaporate, and examine the plate under short-wavelength UV light: the chromatograms show principal spots at about the same RF value. Estimate the intensities of any secondary spots observed in the chromatogram of the Test solution by comparison with the spots in the chromatograms of the Standard solutions: no secondary spot from the chromatogram of the Test solution is larger or more intense than the principal spot obtained from Standard solution B (0.3%), and the sum of the intensities of all secondary spots obtained from the Test solution is not more intense than the principal spot obtained from Standard solution A (1.0%).
Diluent Use Mobile phase.
Phosphate buffer, Mobile phase, System suitability solution, and Chromatographic system Proceed as directed in the Assay.
Test solution Dissolve an accurately weighed quantity of Omeprazole in Diluent to obtain a solution containing about 0.16 mg per mL. [notePrepare this solution fresh.]
Procedure Inject equal volumes (about 40 µL) of the Test solution and Diluent into the chromatograph, and allow the Test solution to elute for not less than two times the retention time of omeprazole. Record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity in the portion of Omeprazole taken by the formula:
100(ri / rs)in which ri is the peak response for each impurity, and rs is the sum of the responses of all of the peaks: not more than 0.3% of any individual impurity is found, and the sum of all impurities is not more than 1.0%.
Phosphate buffer Dissolve 0.725 g of monobasic sodium phosphate and 4.472 g of anhydrous dibasic sodium phosphate in 300 mL of water, dilute with water to 1000 mL, and mix. Dilute 250 mL of this solution with water to 1000 mL. If necessary, adjust the pH with phosphoric acid to 7.6.
Mobile phase Prepare a filtered and degassed mixture of Phosphate buffer and acetonitrile (3:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
Diluent Prepare a mixture of 0.01 M sodium borate and acetonitrile (3:1).
Standard preparation Dissolve an accurately weighed quantity of USP Omeprazole RS in Diluent, and dilute quantitatively, and stepwise if necessary, with Diluent to obtain a solution having a known concentration of about 0.2 mg per mL.
Assay preparation Transfer about 100 mg of Omeprazole, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Diluent to volume, and mix. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with Diluent to volume, and mix.
System suitability solution Dilute a volume of Standard preparation with Diluent to obtain a solution containing about 0.1 mg of USP Omeprazole RS per mL.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L7. The flow rate is about 0.8 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the capacity factor, k¢, is not less than 6.0; the column efficiency is not less than 3000 theoretical plates; the tailing factor is not more than 1.5; and the relative standard deviation for replicate injections is not more than 1.0%.
Procedure Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C17H19N3O3S in the portion of Omeprazole taken by the formula:
500C(rU / rS)in which C is the concentration, in mg per mL, of USP Omeprazole RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information Please check for your question in the FAQs before contacting USP.Chromatographic Column
USP32NF27 Page 3132Pharmacopeial Forum: Volume No. 31(4) Page 1100
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.