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Endotoxin Filtration

Endotoxin filtration is a critical process utilized in various industries to eliminate endotoxins from liquids and solutions. The infiltration of even trace amounts of endotoxins into pharmaceuticals, medical devices, and other products can pose significant health risks.

What are Endotoxins?

Endotoxins also known as lipopolysaccharides (LPS) are potent toxins found in the cell walls of gram-negative bacteria. They are released into the environment when these bacteria are destroyed or disrupted, and they can have serious consequences when introduced into the bloodstream or other bodily fluids. Endotoxins can cause fever, shock, organ failure, and other life-threatening complications.

Why is Endotoxin Filtration Important?

The significance of endotoxin filtration cannot be overstated, especially in sectors where product safety and quality are non-negotiable. Here are some key reasons why endotoxin filtration is crucial:

  • Health and Safety: Endotoxin contamination can lead to severe health issues in both humans and animals, making the removal of endotoxins a critical step in product safety.
  • Regulatory Compliance: Many industries are subject to strict regulatory standards, mandating the control and elimination of endotoxins to meet compliance requirements.
  • Product Quality: Endotoxins can compromise the quality and efficacy of pharmaceuticals, medical devices, and other products, making their removal essential for product integrity.

Methods of Endotoxin Filtration

  • Positively Charged Pleated Membrane Filters: A common method used for endotoxin removal. This technique uses pleated membranes with retention ratings between 1.0 and 0.1 microns. This removes intact bacteria via size exclusion, however, endotoxins are much smaller and are removed through absorption. Endotoxins are negatively charged and therefore are removed with positively charged membranes.
  • Ultrafiltration/Reverse Osmosis Membranes: Have much smaller pore sizes compared to pleated membrane filters, ranging from 1 to 100 nanometers. They are rated by molecular weight cut-off. Endotoxins are typically around 15 kilo Daltons (kDa), and membranes that are rated around 5-10 kDa molecular weight cut-off are used for endotoxin removal. However endotoxins can become aggregated and weigh around 400 to 900 kDa, this allows the membranes to be rated at a much higher molecular weight cut off closer to 100 kDa. Overall, ultrafiltration & reverse osmosis is not recommended for endotoxin removal with large protein solutions, on the other hand, it is highly effective at removing endotoxins from small molecule-based solutions.
  • Charge-Modified Depth Filters: More open mechanical pore sizes than other endotoxin filtration methods. These rely less on mechanical removal, allowing larger particles to pass through while reducing the endotoxins that are present in products or ingredients via positive charge sites. Typically, charged depth filters can reduce endotoxins by 4-5 log. However, it can be more challenging to prove the integrity of these filters compared to other endotoxin filtration methods.
  • Activated Carbon Filters: An adsorbent filter that removes colors, odors, and bacterial endotoxins. Activated carbon is great at removing endotoxins by a 4-log to 5-log reduction value, however, it can also remove other important substances from the liquid. This can make it great for some applications but not work at all for others depending on your filtration goals.

Endotoxin Filtration Recommendations

Selecting the appropriate endotoxin filtration method is a critical decision and is influenced by various factors. Making an informed choice ensures the effectiveness of the filtration process and the preservation of product quality. Here are key considerations to guide you in choosing the right endotoxin filtration method:

Pore Size

The pore size of the filtration being used is a crucial factor in determining its efficiency. Endotoxins vary in size, and selecting the appropriate pore size is essential to ensure optimal filtration while keeping your product quality. Consider the molecular weight and size distribution of the endotoxins present in your application. For example, smaller pore sizes such as ultrafiltration are highly effective at removing endotoxins but can remove other important substances from the liquid. In cases like this positively charged pleated membrane filters like our BRHNY+ can offer exceptional removal with a larger pore size.

Flow Rates

Understanding the required flow rates for your specific application is essential for maintaining optimal filtration performance. High flow rates are desirable in large-scale industrial processes, while more delicate applications may benefit from slower flow rates to ensure thorough filtration. For example, if you are interested in higher flow rates charged depth or pleated membrane methods may be best, on the other hand, if you have slower flow and are looking for highly effective endotoxin removal, ultrafiltration membranes are an excellent option. Evaluate the flow characteristics of different filtration methods and choose a method that aligns with your specific needs.


Evaluating the overall cost of an endotoxin filtration system involves considering not only the initial investment but also the ongoing maintenance and consumable expenses. While high-performance filtration methods may come with a higher initial cost, they could offer long-term savings by minimizing downtime and reducing the frequency of filter replacements. For example, reverse osmosis membranes can be extremely cost-effective if they are removing a specific size of contaminants however if the contaminants are a range of sizes they can be expensive and require tons of maintenance. Factor in the total cost of ownership to make a cost-effective decision.

Compatibility with Application

Different endotoxin filtration methods have varying degrees of specificity and compatibility with different applications. Consider the nature of your product, the required level of endotoxin removal, and any potential interactions with the filtration method. For example, positively charged pleated membrane filters offer endotoxin removal until all the positively charged ions have been used, whereas a reverse osmosis membrane is removed by mechanical separation.

Validation and Compliance

Ensure that the chosen endotoxin filtration meets the regulatory standards and industry requirements. Depending on the industry, compliance with guidelines such as Good Manufacturing Practice (GMP) and Good Laboratory Practice (GLP) may be mandatory. Select a filtration method that is validated to remove endotoxins and has the proper documentation to meet regulatory standards and ensure the integrity of your products.

System Scalability

Consider the scalability of the filtration system to accommodate changes in production scale. A filtration method that is easily scalable allows for seamless integration into larger processes without compromising efficiency. This flexibility is particularly crucial for industries experiencing growth or fluctuations in production demands.

Consultation with Experts

When in doubt, seek guidance from experts in the field of endotoxin filtration. Engage with professionals who understand the nuances of different filtration methods and can provide tailored recommendations based on your specific requirements. Global Filter’s team is open to any questions and would be happy to collaborate with you to ensure that you make an informed decision aligned with industry best practices.

By carefully considering these factors, you can confidently choose the right endotoxin filtration method for your application. Whether it’s charged pleated membrane filtration, ultrafiltration/reverse osmosis, charge-modified depth filters, or activated carbon filters, aligning the method with your unique needs is key to achieving optimal results in endotoxin removal.

Remember, Global Filter’s experienced team is available to provide assistance and guidance in selecting the most suitable endotoxin filtration solution for your application. Contact us to discuss your requirements and explore how our products can support your filtration needs effectively.