Assay Method (E)

Assay Method of 

Econazole Nitrate Cream

Buffer	Prepare the phosphate buffer by dissolving 2.5 g of potassium dihydrogen orthophosphate and 2.5 g of dipotassium hydrogen orthophosphate in 1000 ml of water.
Ratio	Phosphate buffer: Methanol = 1 : 3
Standard	Weigh and transfer about 100 mg working standard of Econazole Nitrate in a 100 ml volumetric flask, dissolve in 75 ml of Methanol then shake for 15 minutes and dilute with phosphate buffer up to the mark ( 100 ml) and mix well. Transfer 10 ml of this solution into a 100 ml volumetric flask and up to mark with mobile phase.Filter this solution with 0.2 mm membrane filter before injection.
Sample	Take an amount of cream sample equivalent 10 mg of Econazole Nitrate in a 100 ml volumetric flask, dissolve in 75 ml of Methanol and warm on a water-bath for 30 seconds, shake for 1 minute, repeat the process twice and add 25 ml phosphate buffer. Cool in a ice bath for 15 minutes. Filter this solution with Whatman Filter paper then centrifuge for 10 minutes and use the supernant liquid. Filter this solution with 0.2 mm membrane filter before injection.
Condition	ODS2  , 10 m 4.6 x 250 mm / 400 C/ UV at 232 nm/15 minutes

Assay Method of 

 Entecavir Monohydrade Tablet

Buffer	Take 1000 ml of Distilled water & adjust the PH to 3.5 with Glacial Acetic acid. Filter through 0.45 m membrane filter and Degasses.
Ratio	Acetonitrile: Buffer = 50 : 50
Diluents	Buffer Solution
Standard	Accurately weigh and transfer Entecavir Monohydrade equivalent to 20 mg of Entecavir Working Standard in a 100- mlVolumetric flask. Add Diluents (Buffer) and shake for 30 minutes and make the volume up to mark & mix well. Transfer 10 ml of this solution in a 100 ml volumetric flask and add  diluents up to the mark (100 ml) & mix well. Filter this solution with 0.25m membrane filters before injection
Sample	Weigh and powder 20 tablets. Take powder-containing equivalent to 0.5 mg of Entecavir in a 25-ml volumetric flask. Add Diluents (Buffer) and shake for 30 minutes & Sonicate for 10 minutes and make the volume up to mark & mix well. Filter the solution through whatman filter paper no.1.and then filter this solution with 0.25m  membrane filters before injection
Condition	Waters Spherisorb 5 mm ODS2   4.6 ´ 250mm./ UV at 224 nm / 15 minutes.

Assay Method of   

Escitalopram Tablet

Standard	Dissolve about 32 mg of Escitalopram Oxalate WS equivalent to 25 mg of  Escitalopram in 50 ml volumetric flask then add 30 ml methanol & shake for 15 minutes then take 1 ml solution in 50 ml flask and up to mark with same solvent.
Sample	Take sample powder equivalent to 25 mg of  Escitalopram in 50 ml volumetric flask then add 30 ml methanol & shake for 15 minutes then filter by whattman filter paper and take 1 ml solution in 50 ml flask and up to mark with same solvent. Measure the absorbance of sample and standard solution at 238 nm using methanol as blank.

Assay Method of   

Esomeprazole Tablet

Standard	Dissolve about 25 mg of Esomeprazole WS in 60 ml of methanol in a amber colored 100 ml volumetric flask and dilute to 100 ml with same solvent. Dilute 2 ml to 50 ml with methanol.
Sample	Shake a quantity of powder containing 25 mg of Esomeprazole with 60 ml of methanol in a amber colored 100 ml volumetric flask for 20 minutes, add sufficient methanol to produce 100 ml and filter. Dilute 2 ml of the filtrate to 50 ml with methanol. Measure the absorbance of sample and standard solution at 302 nm using methanol as blank.

Assay Method of  

 Eszopiclone Tablet

Buffer	Dissolve 1.76 gm of Di Sodium hydrogen orthophosphate & 13.61 gm Potassium dihydrogen orthophosphate with 950 ml  distilled water into 1000 ml volumetric flask, adjust the pH 3.5 ± 0.05 with dilute Phosphoric acid  & make volume with distilled water up to 1000  ml.
Ratio	Acetonitrile: Buffer = 40 : 60
Diluents	Buffer Solution
Standard	Accurately weigh and transfer about 10 mg of working standard of Eszopiclone into 100 ml volumetric flask. Add 75 ml of mobile phase  & shake for 40 minutes and dilute with mobile phase up to the mark and mix well. Filter this solution with 0.45 m membrane filter before injection.
Sample	Weigh and powder 20 Tablets. Take powder containing equivalent to 10 mg of Eszopiclone into 100 ml volumetric flask. Add 75 ml of mobile phase & shake for 40 minutes and dilute with mobile phase up to the mark and mix well. Filter the solution by whatman filter paper & finally filter this solution with 0.45 m membrane filter before injection.
Condition	Waters Spherisorb 5 mm ODS2   4.6 ´ 250mm./ UV at 305 nm / 10 minutes. Eszopiclone : 4.0 minutes (approximately)

Assay Method of   

Etodolac Tablet

Standard

Accurately weigh and transfer about 35 mg of working standard of Etodolac  into 50 ml Volumetric flask Add 35 ml of Ethanol  & shake for 15 minutes and  dilute with Ethanol up to the mark and then  Sonicate this solution for 15  minutes Take 2 ml of the solution in a 50 ml volumetric flask. Make the volume up  to mark ( 50 ml ) with Ethanol. (Concentration: 0.028 mg/ml). λ max = 280 nm

Sample

Weigh of 10 tablets and make it powder. Take powder-containing equivalent to 35 mg of Etodolac  in a  50-ml volumetric flask. Add 35 ml of Ethanol & shake for 15 minutes. Dilute with Ethanol up to the mark then  Sonicate this Solution for 15   minutes & filter with Whitman filter paper .Take 2 ml of the solution in a 50 ml volumetric flask. Make  the volume up  to mark ( 50 ml ) with Ethanol. (Concentration: 0.028 mg/ml).λ max = 280 nm

Assay Method of

Etoricoxib Tablet 

Standard

Weigh accurately and transfer about 20 mg Etoricoxib of working standard in a 100-ml volumetric flask. Add 70 ml of methanol and shake for 10 minutes and then make the volume up to mark with methanol. Then dilute 2 ml of this solution to 50 ml with Methanol. Measure the absorbance of the standard at λ max 235 nm taking methanol as a blank.

Sample

Weigh and powder the 20 tablets. Take powder equivalent to 20 mg of Etoricoxib in a 100-ml volumetric flask.  Add 70 ml of methanol and shake for 20 minutes and perform sonication for 20 minutes and then make the volume up to mark with methanol. Filter this solution with Whatman filter paper. Dilute 2 ml of this solution to 50 ml with Methanol Measure the absorbance of the standard at λ max 235 nm taking methanol as a blank.