Essential water quality for COVID-19 testing

COVID-19 or novel coronavirus is wildly spreading across the world and its outbreak has set alarm bells ringing globally. Effective diagnostic methods are crucial to the early diagnosis, prevention and control of the pandemic, such as nucleic acid detection and antigen-antibody detection.

At present, nucleic acid test plays a critical role in the diagnosis of an active COVID-19 infection, especially PCR (polymerase chain reaction) tests because of its efficiency and specificity. PCR is now part of the recommended protocol by World Health Organization (WHO) to detect COVID-19 virus early.

Essential water quality for Virus Research

PCR is a molecular technique to identify small traces of specific pieces of viral DNA or RNA in samples by amplifying such specific pieces of molecules to large quantities to be detected. PCR tests require strict experimental operations as well as reaction conditions, from sample collection, nucleic acids extraction to amplification. As a basic reagent, water serves as a key component and is inseparable from PCR reaction mixture, therefore its quality is proven to have vital implications for final test results. To eliminate interferences, nuclease and bacteria-free water is required for PCR reactions. However, other impurities existing in water can also significantly influence the accuracy of the results.


It may interfere with fluorescence signals and cause erroneous readings.


Commonly heavy metal divalent cations, such as Cu2+, Fe2+, etc. may bind to active site of enzymes thus inhibit their catalytic activity.

In PCR reactions, Taq DNA polymerase is the most crucial catalyst and is very sensitive to the concentration of magnesium cation (Mg2+). A very specific Mg2+concentration is required for PCR optimization. If not controlled, Mg2+containing contaminants in the water background will reduce the accuracy of tests, resulting in false positive results.


Some organic compounds can either inhibit polymerase or bind to fluorescent substances in PCR, reducing the accuracy of experimental which leads to false negative results.


The presence of nucleases contaminants in water will reduce the concentration of the template, leading to high CT values and even false negative results.


Microorganisms contaminants from water can cause non-specific amplification, bringing inaccurate results or even false positive. Meanwhile, a lot of bacteria can release nucleases, organic materials as well as ions that can impede DNA polymerization. In summary, the best practice to get good results in PCR tests is to use ultrapure water during the whole procedures. The following parameters are equally important for such tests: • Resistivity 18.2 MΩ.cm at 250C

• TOC < 5 ppb

• Nuclease and bacteria free

• Microorganisms < 0.01 CFU/mL

A reliable source for ultrapure water can help saving time and money for COVID-19 testing in the long run. RephiLe’s Genie range ultrapure water systems are ideally suited for different needs of diagnostic testing labs.

Customers for Genie water purification systems

Genie laboratory water purification systems are powerful and revolutionary, bringing the maximum user convenience and assurance from the latest technologies to your lab.

Special benefits of Genie systems to PCR based tests:

low-magnesium purification cartridge

A unique low-magnesium purification cartridge, which specifically targets magnesium ions in water to ensure minimum interference with PCR reactions.

RephiBio final filter

RephiBio final filter removes DNase and RNase as well as bacteria, avoiding interferences to PCR reactions.

Other Highlights of Genie water systems·

Advanced wireless communication technologies and more freedom with placement

· Full traceability and comprehensive monitoring of consumables and accessories

· Waterproof control screen, operable with gloves and wet hands

· Compact and small footprint. Smart space utilization.

About RephiLe:

Driven by innovation and quality, RephiLe is a dedicated provider of water purification systems and laboratory filtration products. At the same time, RephiLe produces comprehensive consumables that can be used in Millipore lab water systems with reliable performance. It is RephiLe’s commitment to becoming a partner of choice for customers in the area of life science and biotechnology. The company is striving to bring superior quality, high value and innovative purification tools to enable and accelerate the advancement of the life sciences and technologies. Products are being sold to over 90 countries worldwide.