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Water for Clinical Diagnostics

A gloved hand places a test tube holding a blood sample into a plastic laboratory test tube rack holding other blood samples with various colored lids

In biomedical laboratories, clinical analyzers are critical instruments that require large quantities of purified water to operate continuously in order to perform timely tests. Any water-related issue, such as a deviation in expected quality or flow rate, could cause analyzer downtime, resulting in decreased laboratory productivity and a delay in delivering results to healthcare professionals and their patients.

The information below is intended to support clinical lab managers and anyone responsible for the water purification systems in a biomedical laboratory. Read to learn how to prevent water contaminants from interfering with the delivery of accurate and reliable chemistry, hematology and immunology assays. You’ll also learn how to maintain maximum water system and analyzer uptime for more efficient clinical lab operations.



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CLRW-grade water supports accurate biomedical analyses

Purified water is a critical reagent in biomedical laboratories as it is essential for clinical assays and for rinsing and cleaning automated equipment. Any issues with water—such as contaminants, quality fluctuations or supply interruptions—can lead to clinical analyzer downtime, potential damage, and decreased laboratory efficiency. 

Appropriate water purification is crucial for maintaining laboratory operations and extending the lifespan of analyzers. The Clinical and Laboratory Standards Institute (CLSI) defines the quality of water required for clinical analyzers as Clinical Laboratory Reagent Water (CLRW).1 Using highly purified CLRW-grade water serves two main purposes: 

  • Supports accurate and reliable clinical analyses
  • Protects analyzers from contamination, clogging and damage

Impact of water contaminants on clinical assays

Consistent CLRW-quality water is vital for accurate and reliable assay results in clinical laboratories. Examples of water contaminants and their potential impacts on sensitive biomedical analyses include:

  • Inorganic ions (e.g. sodium, calcium, magnesium, chloride, etc.) can act as catalysts in organic and biochemical reactions.
  • Organic molecules may disturb biological experiments.
  • Bacteria and their by-products [e.g. alkaline phosphatase (ALP)]: Bacteria can contaminate samples and disrupt instrument operations; bacterial ALP may interfere with alkaline phosphatase used as a detection enzyme in immunoassays.
  • Particulates and colloids (e.g. silica, pollen, salts) can interfere with analyses, clog analyzers and reduce their lifespan.

Given the significant impact of water on clinical assays, laboratories should treat water as a critical reagent. Attention must be paid to water quality for each application. While clinical analyzers generally require CLRW-quality water, specific analyses (such as molecular biology, LC-MS, HPLC, or ICP-MS) may necessitate ultrapure water. Proper design, selection, and maintenance of water purification units can mitigate issues related to water quality, reduce instrument downtime, and enhance laboratory productivity and reliability.

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1. Clinical and Laboratory Standards Institute (CLSI). Preparation and Testing of Reagent Water in the Medical Laboratory. 5th ed. CLSI guideline GP40. (ISBN 978-1-68440-266-3 [Print]; 978-1-68440-267-0 [Electronic]). Clinical and Laboratory Standards Institute, USA, 2024.

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