Water Contaminants in the LaboratoryIn addition to quality laboratory equipment, reagents and consumables, it is necessary to ensure the quality of the water used in lab processes. The accuracy of laboratory tests would be compromised if the water used for clinical and research applications is not free of contaminants. The five major types of contaminants present in tap water which can affect sensitive analytical processes are inorganic ions, organics, particulates and colloids, bacteria and their by-products, and gases. Let’s look at some major consequences of water contaminants on various laboratory processes:

  • Even small quantities of inorganic ions such as sodium, calcium, magnesium or iron and anions such as bicarbonate, chloride and sulfate can impact organic and biochemical reactions because of their catalytic nature. Organic compounds can hamper blotting techniques.
  • Biological experiments such as cell culture and analytical techniques can be affected by dissolved organic compounds of biological origin which contaminate water include humic acids, tannins, and lignin which are the by-products of the decay of plants. Man-made contaminants such as leaching from PVC pipes are another culprit.
  • Lab water quality and lab equipment can be affected by the presence of particulates such as vegetation, rock and sand, and by colloids. Accumulation of suspended particles and particulate matter can block equipment such as filters or columns.
  • Bacteria and microorganisms present in natural and tap water present a challenge when conducting lab experiments. Unwanted proteins released by bacteria can affect results. Bacterial release of nucleases causes nucleic acid sample degradation.
  • Dissolved gases such as nitrogen, oxygen and carbon dioxide in natural water can affect processes such as particulate counting or spectrophotometric measurement and impact specific biochemical reactions.

It should be also noted that the grade of water quality can differ among applications and labs need to maintain the correct level for each:

  • ‘Ultrapure top grade’ for highly sensitive analytical procedures
  • ‘Purified’ for general lab applications including making up of reagents and buffers
  • ‘Primary grade’ for use in lab equipment such as autoclaves and water baths, and washing of glassware

Distillation, ion exchange, microporous filters, ultrafiltration, reverse osmosis, ultraviolet (UV) and radiation are some of the major water purification technologies that are used to remove these impurities. As their levels of efficiency vary, experts recommend that a combination of these technologies be used to remove all contaminants as required for critical applications.