Water Quality and Contaminants in Laboratory Use


Water is one of the major utilities used by the pharmaceutical industry. It is used during the production of the finished product or as a cleaning agent for rinsing vessels and equipment. However, water quality control is a significant concern, and the pharmaceutical industry devotes substantial resources to the development of water purification systems. In this post, we will expound on water quality specifications and common water contaminants in a pharmaceutical setting.

Water Quality Specifications

The American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO) have outlined specifications for water in laboratory use, while the National Committee for Clinical Laboratory Standards (NCCLS) has outlined specifications for water use in clinical laboratories. These NCCLS specifications divide water into three types based on quality: Type 1, 2, and 3.

Type 1 Water

Type 1 laboratory water is the purest water. It undergoes rigorous purification to meet the necessary specifications. These purification systems must include a mixed-bed deionizer to meet the requirements for silica and resistivity. Also, the purification system must have an activated carbon treatment to eliminate chlorine and organic impurities. Lastly, the system needs to have a 0.2-micron post-filtration step to eliminate bacteria and particles.
Type 1 water is used for sensitive analytical procedures such as HPLC, gas chromatography, and ion chromatography. It is also used to prepare buffers and culture media for mammalian cell cultures and in vitro fertilization. Reagents used for molecular biology procedures such as Polymerase Chain Reaction (PCR) and DNA sequencing are also prepared using Type 1 water.

Type 2 Water

Type 2 laboratory-grade water is generated through deionization, distillation, or reverse osmosis with electrode ionization or polishing deionization. This water is utilized for general laboratory purposes, including the preparation of buffers and microbiological culture media. It can also be used to prepare reagents used for chemical analysis. Besides, many use Type 2 laboratory-grade water as feed water for Type 1 water systems.

Type 3 Water

Type 3 grade water can be produced through reverse osmosis depending on the quality of the feed water. This water is utilized to rinse glassware as well as in autoclaves and heating baths. Type 3 water can also be used as feed water for Type 1 water systems.

Water Contaminants

All three grades of water can be attained using the appropriate water purification systems. However, such systems can deteriorate or malfunction, thus allowing contaminants to remain in the water. Some of the most common contaminants in purified water include organics, bacteria, ions, particles, and gases.


Dissolved organics such as decayed animal and plant parts can be found as impurities in purified water. Other organic impurities sources include herbicide and pesticide residues, detergents, proteins, chloramines, and alcohols.


Bacteria and other microorganisms are often found in natural water. Chlorination destroys some of them, but tap water will still contain trace amounts of bacteria. By-products of bacteria such as endotoxins, pyrogens, and nucleases are also detected as contaminants in water, and they interfere with laboratory procedures and results.


Tap water contains inorganic ions, which include cations and anions. Cations commonly found in water include calcium, iron, magnesium, and sodium, while anions include chloride, bicarbonate, and sulfate. Water containing high amounts of ions has low resistivity and high conductivity, affecting laboratory procedures. Inorganic ions also shorten the lifespan of cartridges in deionized systems.


Particles, including sand, clay, and silt, range from 1-10 micrometers in size and end up suspended in water, causing it to appear turbid. Such particles interfere with instruments in many ways; they block valves and narrow flow passages and destroy reverse osmosis membranes.


Gases like nitrogen, oxygen, and carbon dioxide can be found in natural water. Dissolved nitrogen gas forms bubbles that interfere with spectrophotometric procedures. On the other hand, dissolved carbon dioxide forms carbonic acid, which can cause a change in the pH of water.

To conclude, contaminants such as the ones mentioned above can have significant effects on pharmaceutical processes. They interfere with instruments and apparatus, increasing their rate of deterioration. They also disrupt procedures, skew results, and lead to the production of poor-quality products.


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