Water Quality for Clinical Testing and Research Use

My lab is safe! We have a water filtration system and a distiller to purify our water! We use bottled water and other commercially available water in our Lab!

But how sure are you that water quality is optimal to produce quality Lab results?…

Water is an essential reagent in laboratory analysis. It is critical to ensure that the quality of water used during laboratory analysis meets the quality standard of the intended use. This point was emphasized during the recently held ISN-Merck Lab Water Workshop on the 4th of August, 2022.

Many laboratories use water produced from filtration or distillation to run their chemistry analysis; some even go as far as using water from air conditioners and water meant for water dispensers as water sources for their analysers. This practice, and the water from these sources, are not recommended for Laboratory use, as they do not meet the conductivity/resistivity standards as set by Clinical Laboratory Standard Institute (CLSI) Guidelines. Thus, the results produced by using this type of water are questionable and can pose a significant risk to the patient.

These points were highlighted by the Guest Speaker, Dr Adewoyin, during the recently held ISN/Merck Lab water summit where he emphasized the need for water used in the Laboratory to be of Laboratory grade and meet the required standard depending on the use e.g., for clinical lab tests, for molecular research, etc.

Types of Laboratory Water

Water for Laboratory use is of three types:
Type III represents Reverse Osmosis
Type II, which is Deionized Water
Type I, which represents Ultrapure water

Water quality is defined through a series of measurements such as conductivity (µS/cm) or resistivity (MΩ-cm), Total Organic Carbon (TOC) in parts per billion (ppb), and bacterial count (CFU/ml).

Type III – Reverse Osmosis water

Type III grade water, also known as Reverse Osmosis (RO) water, is produced through the reverse osmosis purification technique. It is the starting point for basic laboratory applications such as cleaning glassware, heating baths, media preparation, etc. It is the least pure of all the Pure Water types. The resistivity is usually about 4 MΩ-cm with over 200ppb of total organic carbon. It is used as feedwater in the production of deionized and ultrapure water. The Merck Rios- Di and AFS® E have a Reverse Osmosis stage, the water from this stage is passed into the deionization resins or chamber.

Type II – Deionized Water

Type II (deionized) water is the water of choice for clinical chemistry analyzers. This water is produced through a combination of Reverse Osmosis and Deionization process and has a resistivity of between 10 MΩ·cm to 18 MΩ·cm, with less than 50ppb in total organic carbon. It is the recommended water by the CLSI for general laboratory use. The Merck Rios- Di offered by ISN produces Type II water; this system combines RO and deionization technology to produce Clinical Laboratory Reagent Water (CLRW) used in low-mid volume Chemistry Analyzers such as Roche Cobas C111, and other low-mid volume chemistry analyzers. For the high volume chemistry Analyzers such as Roche Cobas C311, and other high throughput analysers, the AFS® E and Milli-Q® CLX 7000 series are appropriate, as these systems can produce over 300L of pure water per day, sufficient for the water requirement of these chemistry analyzers.

Type I – Ultrapure Water

The purest lab water is Type I ultrapure water, also known as “polished water”. The Ultrapure water is produced through the combination of reverse osmosis, the deionization process, and an additional filtration process to remove special particles that might interfere with the analysis of focus. It is used in HPLC, Blank preparation, preparation of buffers, culture media, and reagents in Molecular Biology and Genomic studies.

The filters used in this water purification process remove several microscopic impurities such as traces of volatile organic compounds, remnants of RNAs/DNAs, microbiological particles, or proteins that might interfere with the analysis of focus. The Ultrapure water has a resistivity of greater than 18 MΩ·cm with less than 10ppb.

Water purification systems/solutions like the Direct-Q® and Milli-Q® Direct come highly recommended for research needing Ultra-Pure water, e.g., molecular studies, genomic studies, etc. In addition to the aforementioned purification processes, these systems (Direct-Q® and Milli-Q® Direct) have a dual-wavelength ultraviolet (UV) light (185nm and 254nm) radiation that kills the remnants of microorganisms up to 99%.

Water Quality is critical.

As we have learned in this article, water plays a universal role in our Laboratory processes; hence, we must ensure that the water we use for clinical testing and research meets the required CLRW standards set by the CLSI. At ISN, we support our customers in ensuring these standards are met by offering a series of Merck Water purification systems (a Global brand) appropriate for their needs.

To know more, please call our toll-free line on  (0802255476) or send us an email at customer@isnmedical.com.

At ISN, we pride ourselves on the quality of products and services we offer to our customers. We provide end-to-end solutions, ensuring that every stage of the process meets quality standards, for both equipment, and reagents