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Clarification & Prefiltration in API Production


The manufacturing of small molecule drugs is a chemical process. Filters are used to assure that the chemicals are free of harmful particulates. Read on for more detailed information on filtration options, or go to the product selection table at the bottom of this page to see specific filter options.


The chemicals used can vary from organic solvents to acids and caustics to purified water. Each chemical ingredient has its own unique characteristics and the filters used must be chosen based on those characteristics.

Clarification & Prefiltration

Clarification and prefiltration can mean many things within different processes. In some cases it may be removing larger particles (larger than 5 µm). In other operations the removal of particles larger than 1μm might be called for. In still others, clarification and prefiltration may be defined as removing particles and some bacteria.

For purposes of this section, we will focus on particle removal. Visit the Bioburden Reduction page to learn more about the initial removal of bacteria in API systems.

Sources of Particles

Particles can be brought into the process with ingredients from outside sources. The process itself can also generate particles. Undissolved powders and solid impurities, for example, may remain after some mixing operations. In all cases, removal of these particles is critical to the quality of the final product. The particles could interfere with downstream processes. They can also cause downstream filters to foul prematurely. Premature filter fouling may interrupt production and increase costs unnecessarily.


Custom systems are designed for new applications and to solve challenges in existing processes. Critical Process Filtration will work with you to design, build and install a cost-effective system that delivers the results you need. Contact us or visit our custom filtration systems page for more information.

Application Summaries

For more information on specific applications, click on the links below to download an Application Summary.

Filters in API Production


Choosing the Right Filter Media

Almost all particle removal filtration applications are done using depth filtration media. Cartridge filters use two forms of depth media. The standard depth filter is a self-supporting tube made using a polymer, most often polypropylene, and forming the tube using the melt-blown or nano-spun process. The other form of cartridge depth filter uses pleated flat sheet media, most often made with polypropylene or fiberglass.

Standard depth filters will capture a range of particle sizes through the thickness of the media. Pleated media filters have the advantage of a large surface area that can hold a higher quantity of particles on that surface than the standard depth filters.

In pleated depth filters, polypropylene is the most widely used material for water and chemical filtration, but fiberglass has better filter efficiency and generally allows higher flows and throughput than polypropylene in final product prefiltration applications.

Our filter media are available in multiple filter formats for all flow ranges. Disc filters support small scale flows in test and research laboratories. Small capsule filters are available for low flow applications such as bench scale systems or small product development systems. Our large disposable capsule filters and cartridge filters are used for larger flow applications ranging from pilot production to full scale operations.

The new High Capacity PES Membrane cartridge filters and capsule filters are examples of filters for bioburden control. Visit our Products page for more information.

The table below shows the filter media in cartridge, capsule and disc filter configurations. We also have sanitary housings for filter cartridges. Click on the in the appropriate location to download a data sheet for the filter media and configuration that fits your needs. For a complete list of all Pharmaceutical filters from Critical Process Filtration, click here.


Media Code Filter Media Filter Grade Cartridge Data Sheet Capsule Data Sheet Disc Filter Data Sheet Pore Sizes Available (µm) Features
GDMB Melt-Blown Polypropylene Media Service
1, 3, 5, 10, 20, 30, 50, 75, 100 Continuously spun bonded polypropylene media for consistent 85% nominal performance
NSPD Nano-spun Polypropylene Media Service
1, 3, 5, 7, 10, 20, 30, 40, 50 Very high retention efficiency (99%) and high load capacity to protect downstream processes
PPD Pleated Polypropylene Depth Media Pharmaceutical
0.1, 0.22, 0.45, 0.65, 1.0, 3.0, 5.0, 10, 20, 30, 40, 60, 100 100% polypropylene construction for high purity
NMMB Melt-Blown Nylon Media Service
1, 3, 5, 10, 20, 30, 50, 75, 100 Spun bonded for consistency with broad chemical compatibility
PGD Pleated Fiberglass Depth Media Pharmaceutical
0.22, 0.30, 0.45, 0.65, 1.0, 2.0, 3.0, 5.0, 10, 20, 30 High capacity filters for clarification and prefiltration applications

The filter media used for each process must, of course, be compatible with the fluids used in it. Contact Critical Process Filtration for assistance in determining the compatibility of filter media and support materials with your process.

To estimate the number of filters you will need for your application, use our unique sizing tools.