Explore our comprehensive guide on USP/BP particulate matter testing, featuring light obscuration and microscopic particle count tests for precise results.

Test Procedure – Particulate Matter

1.0     Objective

• • The objective of this General Test Procedure (GTP) is to describe the procedure for carry out the test for Particulate Matter.

2.0     Principle

3.0     Requirements for Particulate Matter Test

• • As per Light Obscuration Particle Matter Count Test

• • Liquid born particle counting system

• • 100 ml capacity cleaned stoppered bottles

• • Hypodermic syringe

• • Magnetic pins
  • Filtered water/ Filtered diluents

• • Laminar flow cabinet

• • As per Microscopic Particle Matter Count Test

• • Compound binocular microscope

• • Stage micrometer

• • Funnel (Minimum diameter of about 21 mm)

• • Circular diameter reticule

• • Vacuum pump

• • Membrane filter

• • 2 suitable illuminators

• • Laminar flow cabinet

4.0     Procedure for Particulate Matter

• Particulate Matter As per USP/BP

• • Light Obscuration Particle Count Test

• • Test apparatus for Particle Count Test

• • The apparatus is an electronic, liquid borne particle counting system that uses a light obscuration sensor with a suitable sample feeding device.

• • Test Preparation

• • Remove outer closures, sealing bands, any loose or shedding paper labels, outside the laminar airflow.

• • Carefully rinses the exterior of the containers with filtered distilled or deionized water withdraw the contents of the containers under test in a manner least likely to generate particles that could enter the sample.

• • Sampling devices having a needle to penetrate the unit closures may also employed.

• • In case if dry or lyophilized products reconstitution may be done, by removing the closure or by injecting diluent with hypodermic syringe having a 1.2µm or finer syringe filter.

• • The number of test specimens must be adequate to provide a statically sound assessment for large volume injections or for small-volume injections where the individual unit volume is 25 ml or more, fewer than 10 units may be tested based on the definition of an appropriate sampling plan.

• • Product Determination

• • Liquid Preparation

• • Volume in Container Less Than 25 ml

• • Prepare the containers as directed under test preparation.

• • Mix and suspend the particulate matter in each unit by inverting the unit by 20 times.

• • Open and combine the content of 10 or more units to obtain a volume of the sample not less than 40 ml.

• • Degas the pooled solution by sonicating for about 30 seconds or by allowing the solution to stand undisturbed until it is free from air bubbles.

• • Gently stir the contents by hand swirling or by mechanical means take care not to introduce air bubbles or contamination.

• • Withdrawn a minimum of four aliquots, each not less than 5 ml in volume into the light obscuration counter sensor.

• • Discard the data from the first portion.

• • For some products, a pool of 15 or more units may be necessary to achieve a pool volume sufficient for four 5 ml sample aliquots, or some products smaller sample aliquots (i.e. less than 5 ml) can be used if the assay result obtainer in the smaller aliquots is validated to give an assessment of batch suitability equivalent to that obtained with the 5 ml aliquots specified above.

• • Volume in Container 25 ml or more

• • Prepare the containers as directed under test preparation.

• • Mix and suspend the particulate matter in each until by inventing the unit by 20 times.

• • Degas the pooled solution by sonicating for about 30 seconds or by allowing the solution to stand undisturbed until it is free from air bubbles.

• • Gently stir the contents by hand-swirling or by mechanical means, take care not to introduce air bubbles or contamination.

• • Withdraw a minimum of four aliquots, each not less than 5 ml in volume into the light obscuration counter sensor.

• • Discard the data from the first portion.

• • Dry or Lyophilized Preparation

• • Prepare the containers as directed under test preparation. Open the containers, taking care not to contaminate the opening or cover.

• • Constitute as directed under test preparation, using the specified volume or filtered water or an appropriated filtered diluent if water is not suitable.

• • Replace the closure, and manually agitate the container sufficiently to ensure dissolution of the drug.

• • Mix and suspend the particulate matter present in each unit by inverting each 20 times prior to analysis.

• • Proceed as directed for the appropriate unit volume under liquid preparations and analyze by withdrawing a minimum of four aliquots each not less than 5 ml in volume into the light obscuration counter sensor.

• • Discard the data from the first portion.

• • Light Obscurations Particles Count Test for Iron – Sucrose Injection

• • Prepare a solution of injection (1 in 40) using water that passed through a filter having a 1.2 µm of filter porosity meets the requirements for light obscuration particle count test for small volume injection.

• • Light obscurations particles count test for Artisunate Injection

• • Inject 1 ml for 60 mg or 2 ml for 120 mg of 5 % w/v Sodium Bicarbonate solution in one vial shake to dissolve (up to 3 minutes) add 5 ml for 60 mg or 10 ml for 120 mg of 0.9 % sodium chloride injection.

• • The solid should dissolve completely leaving no visible residue as un-dissolved matter.

• • The constituted solution complies with the requirements for clarity of solution and light obscuration particle count test for small volume injection.

• Calculation of Particulate Matter:

• • Pooled Samples (Small Volume Injections)

• • Calculate the number of particles in each container by the formula:

PV_t/V_AN

In which,

P   = average particle count obtained from the portion analyzed

V_t   = volume of the pooled sample in ml

V_A = volume in ml of each portion analyzed

N  = number of containers pooled.

• • Individual Samples (Small Volume Injections)

• • Calculate the number of particles in each container by the formula:

PV/V_A

In which,

P   = average particle count obtained from the portion analyzed

V   = volume in ml of the tested unit

V_A   = volume in ml of each portion analyzed.

• • Individual Unit Samples (Large Volume Injections)

• • Calculate the number of particles in each ml of injection taken by the formula:

P/V

In which,

P = average particle count for an individual 5 ml or greater sample volume

V = volume in ml of the portion taken.

• • Interpretation of Particulate Matter Result

• • The injection meets the requirements of the test if the average number of particles present in the units tested does not exceed the appropriate value. if the average number of particles exceeds the limit test the article by the microscopic particle count test.

• Microscopic Particle Count Test

  • Test apparatus for microscopic particle count consists of;

• • Microscope:

• • Use a compound binocular microscope that corrects for changes in interpupillary distance by maintaining a constant tube length.

• • The objective and eyepiece combination of lenses must give a magnification of 100 ± 10x.

• • Illuminators:

• • Two illuminators are required. One is an external, focusable auxiliary illuminator adjustable to give incident oblique illumination at an angle of 10º to 20º.

• • The other is an episcope bright field illuminator internal to the microscope.

• • Circular Diameter Graticule:

• • Use a circular diameter graticule matched to the microscope model objective and eyepiece such that the sizing circles are within 2 % of the stated size at the plane of the stage.

• • Micrometer:

• • Use a stage micrometer, graduated in 10 µm increments, that is certified by NIST.

• • Filtration Apparatus:

• • Use a filter funnel suitable for the volume to be tested, having a minimum diameter of about 21 mm.

• • Procedure:

• • Liquid Preparations:

• • Thoroughly mix the units to be tested by inverting 20 times.

• • Open the units in a manner consistent with the generation of the lowest possible numbers of background particles.

• • Transfer to the filtration funnel the total volume of a solution pool or of a single unit, and apply vacuum.

• • After the last addition of solution, begin rinsing the walls of funnel by directing a low-pressure stream of filtered, distilled or deionized water in a circular pattern along the walls of the funnel before the volume falls below about one-fourth of the fill level.

• • Maintain the vacuum until all the liquid in the funnel is gone.

• • Remove the filtration funnel from the filtration base while maintaining vacuum, then turn of vacuum off, and remove the filter membrane and blunt forceps.

• • Place the filter in a petri dish or similar container, secure in place with double sided tape, and label with sample identification.

• • Allow the filter to air dry in the laminar flow enclosure with the cover a jar.

• • Dry or Lyophilized Preparations:

• • Using a single pool of 10 or more units, or the desired number of single units, proceeds as directed for liquid preparations.

• • Enumeration of Particles:

• • Total Count Procedure:

• • In performance of a total count, the graticule field of view (GFOV) defines by the large circle of the graticule is ignored, and the vertical cross hair is used.

• • Scan the entire membrane from right to left in a path that adjoins but does not overlap the first scan path.

• • Repeat this procedure, moving from left to right to left until all particles that are 10 µm or larger and the number that are 25 µm or larger.

• • For large-volume injections, calculate the particle count, in particles per ml for the unit tested by the formula:

P/V

In which

P = is the number of particles counted

V = is the volume in ml of the solution.

• • For small volume injections, calculate the particle count, in particles per container, by the formula:

P/n

In which

P = is the total number of particles counted and ‘n’ is the number of units pooled (1 in the case of a single unit).

• • The injection meets the requirement of the test if the average number of particles present in the units tested not exceeds the appropriate value.

• Particulate Matter Test as per IP

  • Use flat ended forceps, carefully remove a colour contrast grid membrane filter (pore size less than or equal to 5 µm and of diameter 25 mm) from its container.

• • Wash both side of the membrane with a stream of water that has been further purified by filtration through a suitable membrane to remove particulate matter, start washing at the top of the non-gridded (unprinted), sweeping the stream black and forth across the surface, working slowly from top to bottom so as to wash any loose particles from the surface, repeat the process on the gridded side.

• • Place the membrane (grid side up) on the filter holder base and install the filtering funnel on the base without sliding the funnel over the membrane filter.

• • Invert the assembled unit and wash the inside of the funnel of about 10 seconds with jet filtered water.

• • Allow the water to drain and place the unit on the filter flask.

• • Invert the container of the preparation being examined 20 times in order to mix the contents.

• • Wash the outer surface of the container with a jet of water and remove the closure carefully, avoiding contamination of the contents.

• • Transfer 25 ml of the solution to the funnel, allow to stand for 1 minute, and apply the vacuum and filter.

• • Release the vacuum gently and wash the inner walls but avoid directing the stream into the filter surface.

• • Filter under suction the rinsing. Carefully remove the upper section of the filter assembly while maintain vacuum.

• • Release the vacuum and remove the membrane filter with flat ended forceps.

• • Place the filter with plastic petri slide to which a very thin film of silicone greasy may be applied to hold the filter flat and in place.

• • Ensure that the filter is placed with gridded surface up.

• • Partially cover the petri slide with the lid and allow the filter to dry.

• • Cover the slide carefully on the micrometer stage of the microscope and count the plates on the filter as under 100 × magnification with the incident light at an angle 10º to 20º with the horizontal.

• • Count the number of particles having effective linear dimensions equal to or larger than 10µm, equal to or larger than 25µm or equal to or larger than 50µm.

• • Perform a blank determination, using a membrane filter and assembly.

• • Subtract the total counts obtained in the blank determination from the uncorrected total counts for the test solution.

• • If the blank determination yields more than 5 particles effective linear dimension of 25µm or larger, the operational environment should be considered unsatisfactory and the test is invalid.

• • The preparation meets the requirements of the test if it contains particles within the maximum limits.

• • Visually

• • For Dry Powder: Constitute the solution to the given volume (as specified in label) in test tube.

• • For Liquid: Take 10 ml solution in the test tube.

• • Procedure: Examine the solution on white or black surface in suitable conditions of visibility. It should be clear & practically free from particles that can be observed on visual inspection by the unaided eye.

• • Particulate Matter in Ophthalmic Solutions:

• • Ophthalmic solution should be essentially free from particles, that can be observed on visual inspection, the test describes here in are physical tests performed for the purpose of enumerating extraneous particles with in specific size ranges.

• • Ophthalmic preparation that are suspensions, emulsions or gels are exempt from these requirements as are medical devices, refer to the specific monograph where a question of test applicability occurs.

• • The ophthalmic solution is first tested by the light obscuration procedure. If it fails to meet the prescribed limits, it must pass the microscopic procedure, with its own set up test limits.

• • Where the technical reason the ophthalmic solution cannot be tested by light obscuration, microscopic testing may be used exclusively.

• • Light Obscurations Particles Count Test / Microscopic Particles Count Test:

• • Test apparatus instruments, test environments, test procedure & calculations are same as particulate matter in injections.