Why Ultrapure Water is Essential for Consistent, ReproducibleEndotoxin Results

The Sartorius Arium® Water Systems Delivers Ultrapure Water for Endotoxin Analysis

When doing experiments in a lab that involve water, it’s crucial to use high-quality laboratory water to get accurate and reliable results. Endotoxins are harmful substances found in certain bacteria that can affect the results of tests. When testing for endotoxins, it’s especially important to make sure that all the tools, substances, and water used in the lab are certified to be free of these contaminants.

Getting rid of endotoxins is tough because they can withstand heat and extreme pH levels. Removing them is also tricky because of their structure. To avoid contamination and false results, the best strategy is to prevent exposure to potential sources of endotoxins. Contaminating lab tools and water with endotoxins can lead to incorrect results, making it necessary to redo tests. This is not only inconvenient but also costly, especially when dealing with expensive and short-lived products like cell and gene therapies.

For disposable tools, it’s essential to use plastic ware that the manufacturer certifies as endotoxin-free. However, the water used in the lab can be a source of endotoxin contamination. Addressing this issue is crucial. In an interview with Dr. Kunal Kureja, an Application Scientist for Lab Water at Sartorius AG, the discussion focuses on the type of ultrapure water suitable for endotoxin analysis and how to make sure it’s free of endotoxins through validation and verification processes.

Why is using ultrapure water to perform endotoxin testing important?

Dr. Kureja: Ultrapure water is purified to a higher quality grade than untreated or pure water, with very low levels of impurities. This is particularly important for analytical analysis, as even small amounts of contaminants, such as endotoxins, can lead to false results, impacting both testing time and experiment costs. Today, managing expenses is crucial in the lab, making it even more important to have reliable

Does ultrapure water quality differ, and how?

Dr. Kureja: Yes, the quality of ultrapure water can also vary depending on the components used in the water system. Classical ultrapure water systems typically use ion exchange resins to remove nearly all charged molecules from the water. However, if high-quality analysis is required for analytical or life science experiments, ion exchange resins alone are not sufficient. Additional purification technology is necessary. For example, if endotoxin-free water is required, it is highly recommended to use an ultrapure water system that incorporates ultrafiltration technology. Ultrafiltration technology is based on hollow fibers with a molecular weight cut-off of 5-15 Da. This ensures that impurities such as endotoxins, RNase, and DNase molecules are also removed from the water.

Are there any guidelines that would support users in selecting the right ultrapure water quality?

Dr. Kureja: There are various standards available, such as Pharmacopoeia, ISO, or ASTM, which provide guidelines
for the appropriate water quality required for specific applications. One of the widely recognized laboratory standards is the ASTM D1193 water quality classification, which specifies water purification technologies and quality parameters. Additionally, for specific applications, supplementary sub-standards can assist in determining the appropriate water quality needed. For instance, for biological grade water, ASTM D5196 can be taken into consideration.

Regarding endotoxin testing, the kinetic-turbidimetric
LAL test is a quantitative method known for its higher sensitivity compared to gel-clot methods, with a detection limit of 0.001 EU/mL (EU = endotoxin units). Therefore, water with an endotoxin content below 0.001 EU/mL is required. Water purified using Arium® Pro VF is capable of achieving an endotoxin content below 0.001 EU/mL, depending on the quality of the feed water.

Are there some guidelines on the best practices and potential pitfalls when handling ultrapure water?

Dr. Kureja: When working with ultrapure water, it is crucial to follow some simple rules to ensure high water quality.
The first rule is to always work with freshly produced ultrapure water, as stored water can be prone to adsorbing impurities, leading to a higher risk of cross-contamination and changes in conductivity, as well as an increased level of impurities. For further information on this topic, which is really crucial, please download the free poster here, where we have a nice and brief overview of the so-called Golden Rule and how to handle ultrapure water.

Besides endotoxins, what other contaminants could play a role in quality testing labs, specifically with regard to analytics?

Dr. Kureja: For sure, aside from endotoxin testing, there are a lot of other critical analyses. For example, inorganic salts can interfere with protein-protein interactions, lead to inaccurate elemental and ion measurements, and inhibit DNA polymerase activity, which can lead to poor PCR results. Whereas organic compounds can cause increased baseline noise and reduced sensitivity during HPLC experiments, and decreased HPLC column life. Therefore, it is always essential that you consider what type of analysis you want to proceed with, and which impurities may affect your assay.

A water purification system is one of the vital investments you make when building a laboratory. Water purification systems come in many different sizes and capabilities. Ultimately, you can use one ultrapure water system for more than one applicative technology. If you need help finding the right system, we recommend contacting us.

One last question: Does implementing an ultrapure water system in the lab depend on the available space and the system’s quality?

Dr Kureja: Laboratory water purification systems can be configured in two ways: centralized or point-of-use. A centralized system provides water to an entire facility, while point-of-use systems are dedicated to one laboratory or application. Instrument systems with flexible installation help manage limitations around space in the laboratory.

Dr Kureja: Laboratory water purification systems can be configured in two ways: centralized or point-of-use. A centralized system provides water to an entire facility, while point-of-use systems are dedicated to one laboratory or application. Instrument systems with flexible installation help manage limitations around space in the laboratory.

This information has been sourced, reviewed and adapted from materials provided by Sartorius Lab Instruments GmbH & Co. KG.

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