1.0) Description: Visual

2.0)   Average Weight: Check weight of 20 tablets at randomly and calculate the average weight by formula :  wt of 20 tablets (gm) x 1000 / 20. found avg. wt in mg

3.0)                  Uniformity of weight:

Weigh 20 tablets selected at random and calculate the average weight. Not more than two of the individual weights deviate from the average weight by more than the percentage shown in table.

Tablets were weighed individually and the percentage of deviation of its weight from the average weight was determined for each tablet. Formula for calculate the percentage of deviation = (experimental weight – theoretical weight)    x 100%

theoretical weight


Average weight of tablets Percentage deviation
More than 80mg but Less than 250mg 7.5%
250mg or More 5%

4.0)      Identification Test:

  1. To an amount of the finely powdered tablets containing about 10 mg of Clonazepam in a small separator add 25ml of water, shake for 2 minutes, and extract with two quantities, each of 40ml, of chloroform. Pass the extracts through anhydrous sodium sulphate, combine them, and evaporate to dryness at room temperature with the aid of a stream of nitrogen; the residue complies with the following test.

Determine by infrared absorption spectrophometer. Compare the spectrum with that obtained with Clonazepam reference standard or with the reference spectrum of Clonazepam.

  1. In the assay the chromatogram obtained with the test solution corresponds to the chromatogram obtained with the reference solution.

5.0)      Hardness:

The standard method used for tablet hardness testing is compression testing. The tablet is placed between two jaws that crush the tablet. The machine measures the force applied to the tablet and detects when it fractures. Although compressive force is applied to the tablet, along the diameter of the tablet at right angles to the applied force.

6.0)      Disintegration Time:

Unless otherwise stated in the individual monograph, introduce one tablet into each tube and add a disc to each tube. The assembly is suspended in the liquid medium in a suitable vessel, preferably a 1-litre beaker. The volume of liquid is such that the wire mesh at its highest point is at least 15mm below the surface of the liquid, and at its lower point is at least 25mm above the bottom of the beaker. At no time should the top of the basket-rack assembly become submerged. There is a thermostatic arrangement for heating the liquid and maintaining the temperature at 37±2°.

If 1 or 2 tablets fail to disintegrate, repeat the test on 12 additional tablets; not less than 16 of the total of 18 tablets tested disintegrate.

If the tablets adhere to the disc and the preparation under examination fails to comply, repeat the test omitting the disc. The preparation complies with the test if all the tablets in the repeat test disintegrate.

7.0)      Dimension of Tablet:

Length, breadth and thickness are determined by vernier in mm

8.0)      Friability:

The test is applicable to compressed tablets and is intended to determine the physical strength of tablets. For tablets with an average weight of 0.65 gm or less take a sample of whole tablets corresponding to about 6.5gm and for tablets with an average weight of more than 0.65gm take a sample of 10 tablets.

            Dedust the tablets carefully and weigh accurately the required number of tablets. Place the tablets in the drum and rotate it 100 times (25 rpm for 4 minutes). Remove the tablets, remove any loose dust from them and weigh them accurately. The test is run only once unless the results are difficult to interpret or if the weight loss is greater than the target value, in which case, the test is repeated twice and the mean of the three tests is determined.

          Formula: initial wt. – after friability wt. x100 / initial wt.

            A maximum loss of weight (From a single test or from the mean of three tests) not greater than 1.0 percent is acceptable for most tablets.

9.0)      Leak test:

The apparatus is used to test for the integrity of packed strips, blisters and Alu-Alu Blister pack containing tablets. Ensure apparatus bath is filled with purified water upto mark indicated and add 0.5% crystal violet solution in water. Samples are placed into the desiccators and the lid is placed in position. The pump starts to produce a vacuum 15inHg inside the desiccators and the vacuum is held for 1 minute. The sample remains at the required vacuum level for given time interval buzzer will sound after time is over and will cut off the vacuum pump. As the package is immersed in a colored dye solution the venting of the desiccators will allow any holes to be penetrated by the dye and the contents of the flexible packaging will also be stained with the same coloring material.

Examine all the strips for any leakage by opening the pockets manually. If anyone pocket shows evidence of leakage, reject the sample, stop the Blister / Strip machine and immediately take corrective action.

10.0)    Uniformity of content: Determined by liquid chromatography, as described under assay.

            Test solution: To one tablet add 5 ml of the mobile phase mixture, disperse with the aid of ultrasound for 10 minutes, dilute, if necessary, with sufficient of the mobile phase to produce a solution containing 0.01% of Clonazepam and filter

            Calculate the content of Clonazepam in the tablet

11.0)    Assay: Determined by liquid chromatography.

Reference solution: Weigh 25mg of Clonazepam reference standard in 50ml volumetric flask. Add 10ml of mobile phase and dissolve. Sonicate the standard & shake by mechanical means for 5 min, add 40ml of mobile phase and shake. Dilute 1ml to 50ml with mobile phase. Shake and filter.

Test solution: Weigh and powder 20 tablets. Weight sample containing 1mg Clonazepam in 100ml of volumetric flask. Add 10ml of mobile phase and sonicate and makeup to the mark with mobile phase. Filter the solution and inject.

            Chromatographic system:

  • A stainless steel column 15cm X4.6mm, packed with octadecylsilane bonded to porous silica (5µ)
  • Mobile Phase: Buffer:Acetonitrile(50:50)

Buffer: 6.8gm KH2PO4→500ml pH-3

  • Flow rate: 1.0ml per minute,
  • Spectrophotometer set at 254nm,
  • Injection volume: 20µl

Inject reference solution. The test is not valid unless the relative standard deviation for replicate injections for each peak is not more than 2.0 percent.

Inject reference solution and the test solution.

Calculate the content of Clonazepam in tablet.

             Acceptance criteria: 90.0%-110.0%


Area of Test      STD Wt.(mg)         1                100                Potency

—————–X—————–X——-X—————–X————–X   Average weight

Area of STD        100                         50      Test Wt.(mg)     100