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When working in laboratories and hospitals, it’s crucial that any contaminants found in water are removed immediately, before they cause any damage.
Each impurity carries its own risks to chemical and biological research, not to mention the detrimental effect they cause to the quality of pure water. Here we discuss the 8 main types of water contaminants, and how they can be prevented.
1. Microorganisms
Bacteria, algae and fungi all regularly interfere with sterile research applications. Bacteria can adversely influence cell and tissue culture by competing at enzyme-active sites on substrates.
If free-floating bacteria form biofilms on surfaces, they can be extremely difficult to remove. These biofilms can grow for several years, spontaneously releasing bursts of bacteria, along with their associated endotoxins and nucleases.
These nucleases then break down DNA and RNA in samples, and the endotoxins will have a negative effect on the growth and function of cells.
2. Viruses
Viruses – referred to as non-living nucleic acids – adversely affect tissue and cell growth. They’re extremely small, with most of them falling between 0.01 – 0.3 microns, and they can survive for long periods of time. Once they’ve been spotted in water, they should be removed as soon as possible.
3. Pyrogens
For mammalian cell cultures, and the preparation of solutions or devices that will later have contact with humans and other mammals, it’s crucial that the water used is pyrogen-free.
The most significant component of pyrogens – a form of endotoxin – is lipopolysaccharides (LPS), which is derived from Gram-negative bacteria walls. If LPS gets into the blood or spinal fluid, it can be toxic and cause a fever.
4. Dissolved Inorganic Ions
Silicates, chlorides, calcium, fluorides, magnesium, phosphates, bicarbonates, sulphates, nitrates and ferrous compounds are all forms of dissolved inorganic ions.
The instability in water caused by these ions will negatively influence chemical and biological reactions. Results include the formation of protein-protein and protein-lipid interaction, altering enzymatic activity, and delaying the growth of cells and tissue.
5. Dissolved Organic Compounds
These are derived from animal and plant decay, in addition to any human activities that involve the introduction of alcohol, protein, pesticides, chloramine, herbicides or detergents into the environment.
Dissolved organic compounds interfere with high performance liquid chromatography (HPLC), gas chromatography and fluoroscopy.
6. Dissolved Gases
Water contains naturally dissolved carbon dioxide, nitrogen and oxygen, but these gases can alter the pH of lab water, which upsets the ionic balance. Concentrations of oxygen and nitrogen can affect the rate of biochemical reactions; and high concentration of dissolved gases can cause a bubble formation, which obstructs the flow through chromatography columns and micro-channels.
Dissolved carbon dioxide raises water acidity, reducing the capacity of ion exchange resins in DI systems.
7. Suspended Particles
When large suspended particles of clay, sand, silt or vegetation between 1 – 10µm are found in water, they cause turbidity and settle at the bottom.
Suspended particles can foul reverse osmosis membranes, filters and chromatography columns, especially if the system stems from a reservoir or tank within the building.
8. Colloidal Particles
Colloidal particles are much smaller than suspended particles, at just 0.01 – 1.0µm, and they don’t settle.
Colloidal particles regularly interfere with analytical techniques, and bypass ion exchange resins, which result in lower resistivity in DI water.
How to Prevent Contaminants
The main way to prevent and remove contaminants are through water purification systems. Different technologies have been created, each specialising in the removal of specific contaminants.
For example, whilst the process of distillation won’t remove ionised gases, inorganic ions or dissolved non-ionised gases, they will filter out bacteria and pyrogens.
Reverse osmosis (RO) is hailed as one of the most effective ways of removing contaminants, as this process removes up to 99% of impurities in water. Dissolved organics and ionics, suspended impurities, bacteria and pyrogens are all removed from water when RO is used.
To conclude, contaminants can be very damaging to water. Once found, they should be removed as soon as possible, using the most effective form of water purification technology.