Assay Method (L)

Assay Method of

Lactulose  Solution

Buffer	1.15 gm sodium dihydrogen phosphate to 1000 ml water.
Ratio	Buffer : Acetonitrile = 15 : 85
Diluents	Water : Acetonitrile = 50 : 50
Standard	Take about 2 gm of Lactulose substance WS  with 20 ml water (HPLC grade )  than add 25 ml acetonitrile then heat gently and cool finally make volume 50  ml with water (HPLC grade ) & mix well. Filter this solution with 0.45m   membrane filter before injection.
Sample	Take sample about 2 gm of Lactulose substance with 20 ml water (HPLC  grade ) than add 25 ml acetonitrile then heat gently and cool finally make  volume 50 ml with water (HPLC grade) & mix well. Filter this solution  with 0.45m membrane filter before injection.
Condition	Amino Bonded Column, 4.6 ´ 250mm./ Cell Temp.38º C / Oven Temp. 40º C /Refractive Index   Detector / Flow Rate 1.4 ml per minute / Inject   Volume 80 micro liter / Run Time 20 minutes  / Retention Time 9 – 12 minutes.

Assay Method of

Lansoprazole  Capsule

Solvent	Methanol
Standard	50 mg ---® 100 ml ---® Take 1 ml ---® 50 ml
Sample	Same as standard. Take the absdrobance at 284 nm.

Assay Method of

Leflunomide  Tablet

Solvent	Methanol
Standard	50 mg ---® 100 ml ---® Take 1 ml ---® 50 ml
Sample	Same as standard. Take the absdrobance at 284 nm.

Assay Method of

Lercanidipine HCl  Tablet

Solvent	Methanol
Standard	25 mg ---® 50 ml ---® Take 5 ml ---® 50 ml (Shake 20 minutes)
Sample	Same as standard. Take the absdrobance at 355 nm.

Assay Method of

Levamisole Hydrochloride Tablet

Standard	Dissolve about 25 mg of Levamisole Hydrochloride in 60 ml of water and dilute to 100 ml with same solvent.
Sample	Shake a quantity of powder containing 25 mg of Levamisole Hydrochloride (1mg of Levamisole is equivalent to 1.178 mg of Levamisole Hydrochloride) with 60 ml of water for 20 minutes, add sufficient water to produce 100 ml and filter.
System	To 1 ml of each standard and sample preparation, add 0.5 ml of 6 % w/v sodium hydroxide and 1 ml of 5 % w/v nitroprusside solution, followed by 5 ml of 2.0 % w/v boric acid solution. Shake well and allow to stand for 2 minutes. Dilute to 10 ml with water. Measure the absorbance at 540 nm, against reagent blank , prepare in the same manner , using 1 ml of water.

Assay Method of

Levofloxacin  Tablet

Solvent	Methanol
Standard	50 mg ---® 100 ml ---® Take 1 ml ---® 100 ml (Shake 20 minutes)
Sample	Same as standard. Take the absdrobance at 226 nm.

Assay Method of

Levofloxacin  Solution

Buffer	Add 3 ml Triethylamine in 1000 ml of water and adjust the pH to 3.2 with dilute Phosphoric acid.
Ratio	Buffer : Acetonitrile = 60 : 40
Diluents	Buffer Solution
Standard	Take about 25.625 mg of Levofloxacin Hemihydrate WS equivalent to 25 mg of  Levofloxacin in a 25 ml volumetric flask. Add 20 ml diluents and shake for 10 minutes and make the volume 25 ml  with diluents and mix well. Dilute 2.5 ml to 50 ml with same diluents & mix well. Filter this solution with 0.45m membrane  filter before injection.
Sample	Take 1ml solution equivalent to 25 mg of Levofloxacin   in a 25ml volumetric flask. Add 20 ml of  diluents and shake for 10 minutes & than make the volume 25 ml with diluents and mix well. Dilute  2.5 ml to 50 ml with same diluents & mix well. Filter this solution with 0.45 m membrane filter  before injection.
Condition	Waters Spherisorb 10 mm ODS1 4.6 ´ 250mm./ 40º C / UV at 295 nm / 10 minutes.

                                                                              Assay Method of

Levosalbutamol Sulphate  Tablet

Buffer	Dissolve 2.50 gm of Potassium dihydrogen orthophosphate & 2.87 gm Sodium Heptane sulphonate with 950 ml  distilled water into 1000 ml volumetric flask, adjust the pH 3.65 ± 0.05 with Phosphoric acid  & make volume with distilled water up to 1000  ml.
Ratio	Buffer ( 78% ) : Acetonitrile ( 22% )
Standard	Accurately weigh and transfer about 12 mg of working standard of Levosalbutamol Sulphate into 100 ml volumetric flask. Add 75 ml of mobile phase & shake for 20 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 Levosalbutamol into 100 ml volumetric flask. Add Add 75 ml of mobile phase & shake for 20 minutes and dilute with mobile phase up to the mark and mix well. Filter this solution with whatman filter paper & finally filter this solution with 0.45 m membrane filter before injection.
Condition	Waters Spherisorb  C8 5.0 mm 4.6 x 150 mm / 30°C  / UV at 220 nm / 10 minutes Levosalbutamol Sulphate : 3.5 minutes (approximately)

                  Assay Method of

Levosalbutamol Sulphate Solution

Standard	Accurately weigh and transfer about 60 mg of working standard of Levosalbutamol Sulphate INN equivalent 50 mg of Levosalbutamol into 50 ml volumetric flask. Add 35 ml of distilled  water & shake for 10 minutes and dilute with distilled water up to the mark and mix well. Dilute 5 ml of this solution to 50 ml with distilled water.
Sample	Take 25 ml syrup equivalent to 5 mg of Levosalbutamol into 50 ml volumetric flask. Add 35 ml of distilled water & shake for 10 minutes and dilute with distilled water up to the mark and mix well Each mg of Levosalbutamol equivalent to 1.200 mg of Levosalbutamol Sulphate
Procedure	Take 5 ml of Standard & Sample solution each in two separate 25 ml volumetric flask. Add 5 ml of 1M Sodium carbonate solution & 0.5 ml of P-Amonophenol solution to each flask. Dilute to 25 ml with water. Keep at rest for 25 minutes. Measure the absorbance of the standard & sample solution at the maximum at 625 nm taking water as blank.

Assay Method of

Lidocaine Hydrochloride Injection

Sample

To a quantity of sample containing 0.100 g of Lidocaine Hydrochloride (10 ml ) add 10 ml of 2M sodium hydroxide. Mix. Extract two times each with 30 ml of chloroform. Wash each extract with the same 10 ml of water. Filter the washed extract through the filter paper moistened with chloroform. Wash the filter paper with 10 ml of chloroform. Evaporate the total chloroform extract to dryness. Dissolve the residue in 30 ml of glacial acetic acid.  Add 6 ml of 5% w/v Mercury (II) acetate solution.  Titrate with 0.1N perchloric acid using crystal violet solution as indicator. Each ml of 0.1N perchloric acid VS is equivalent to 27.082 mg of Lidocaine Hydrochloride. Calculation  : Volume of VS in ml x Factor of VS x 27.083 X 100 / Weight of Lidocaine HCl in mg

Assay Method of

Linzolid INN  Raw Material

Solvent	Methanol
Standard	20 mg ---® 100 ml ---® Take 5 ml ---® 100 ml (Shake 20 minutes)
Sample	Same as standard. Take the absdrobance at 258 nm.

Assay Method of

Loratadine Syrup

Mobile Phase	Dissolve 1.74 g K2HPO4 in 500ml of water and make up to 1000ml with water. Mix three parts of this buffer with 8 parts of methanol. Adjust pH of this solution to  7.8  ± 0.1 with phosphoric acid . Filter through 0.45µ Filter and degass.
Standard	Weigh accurately about 50mg Loratadine WS and transfer in a 50 ml volumetric flask. Add 35 ml of Methanol Shake for 10 minutes and make the volume up to the mark (50 ml ) with methanol. Filter the solution and transfer 10ml of the filtrate in a 25ml volumetric flask. Make the volume up to the mark with Methanol and filter this solution with 0.45µ membrane filter before injection.
Sample	Shake Lora 60 ml Suspension for 30 minutes . Take 20 ml Suspension (equivalent to 20 mg of Loratadine) in a separating funnel. Add 30 ml chloroform to it and shake well for extraction.  Separate the organic layer. Repeat the process. Combine the extracts and wash it with 15 ml distilled water. Take the extract in a conical flask and evaporate it on water bathe or rotary evaporator. Dissolve the residue with 20 ml methanol and then take in a 50 ml volumetric flask, make the volume up to the mark (50 ml) with Methanol & shake well. Filter the solution using Whatman filter paper at first and then filter through 0.45 µ membrane filter before injection.
Condition	µ- bondapaek  C18, 250 x 46 mm, 5.0 µ pore size / Ambient / 254 nm / 25 minute / 20 µl

Assay Method of

Loratadine + Pseudoephidrine  Tablet

See ------à Next --------à Pseudoephidrine HCl +  Loratadine Tablet

Assay Method of

Losartan Potassium  Tablet

Buffer	Dissolve 0.3854 g of Ammonium acetate in 1000 ml of water.
Ratio	Mix 50 volume of buffer & 0.1 volume of Triethylamine with 50 volume of acetonitrile, filter through a 0.45-micron membrane filter and degas.
Standard	Dissolve about 50.0 mg of Losartan Potassium WS in 70 ml of water and dilute to 100 ml with the same solvent. Dilute 5 ml to 25 ml with mobile phase. Filter this solution with 0.45 m membrane filter before injection.
Sample	Shake a quantity of the powdered sample containing about 50.0 mg of Losatran Potassium in 70 ml of water for 30 minutes, dilute to 100 ml with the same solvent and then filter. Dilute 5 ml filtrate to 25 ml with mobile phase. Filter this solution with 0.45 m membrane filter before injection.
Condition	C8 5.0 mm 4.6 x 250 mm / UV at 237 nm / 40 mL / 10 minutes

Assay Method of

Losartan Potassium + Hydrochlorothiazide Tablet

Buffer	Dissolve 385.4 mg of Ammonium acetate with 950 ml distilled water into 1000 ml volumetric flask & add 1 ml of Triethylamine & mix well. Adjust the pH 3.0 ± 0.05 with dilute Phosphoric acid  & make volume with distilled water up to 1000  ml.
Ratio	Buffer ( 40% ) : Acetonitrile ( 60% )
Standard	Accurately weigh and transfer about 50 mg of working standard of Losartan Potassium & 12.5 mg of Hydrochlorothiazide into 100 ml volumetric flask. Add 40 ml of water & shake for 10 minutes and dilute with methanol up to the mark and mix well. Then transfer 5 ml of this solution into 25 ml volumetric flask & volume up to the mark with mobile phase. Filter this solution with 0.45 m membrane filter before injection.
Sample	Weigh and powder 20 Tablets. Take powder containing equivalent to 50 mg of Losartan Potassium & 12.5 mg of Hydrochlorothiazide into 100 ml volumetric flask. Add 40 ml of water & shake for 10 minutes and dilute with methanol up to the mark and mix well. Filter this solution with Whatman filter paper. Further transfer 5 ml of this solution into 25 ml volumetric flask & volume up to he mark with mobile phase. Filter this solution with 0.45 m membrane filter before injection
Condition	C8 5.0 mm 4.6 x 250 mm / UV at 237 nm / 10 minutes Hydrochlorothiazide  : 3.0 minutes  &  Losartan  Potassium  : 4.0 minutes (approximately)

Assay Method of

Loperamide Hydrochloride Tablet

Sample

Weigh and powder 50 capsules .Take  powder equivalent to 55 mg of Loperamide Hydrochloride in a 250 ml  iodine flask.  Add 40 ml of chloroform , shake for 20 minutes . Filter . Evaporate the filtrate to dryness.  Dissolve the residue in 30 ml of anhydrous glacial acetic acid. Add 6 ml of 5 % w/v Mercury (II) Acetate solution  . Titrate with 0.1N perchloric acid VS using naptholbenzein solution as indicator.1 ml of 0.1N perchloric acid VS   is º 51.35 mg of  Loperamide Hydrochloride