subject: Why Pure Water Is Needed In The Laboratory [print this page] Many instruments and measurement devices in the scientific laboratory, whether it is a research laboratory or a bioscience/medical laboratory, need purified water as a washing agent, reagent mixer, or rinsing agent. The necessity for pure water in these processes can be seen as common sense; contaminated water, or mineralized water can be hazardous to the testing procedures.
Pure laboratory water can be obtained by many methods. There are filtration systems that can result in 99% pure water for the laboratory. Distillation systems are also available to provide a non-mineralized water to be used in sensitive instruments. As can be imagined, mineral content in the rinse water for an automated chemistry analyzer would cause buildup of mineral deposits within the tubing and aspiration systems, which can lead to erroneous results, damage to the expensive probes, and quite possibly voiding the warranty
Distilled water for the laboratory is a frequently used rinse media, as the water is made from evaporative steam, which is condensed in a chamber to remove any possible contaminants such as minerals. This type of purified water is not guaranteed to be without bacteria, nor does it assure against other contaminants that may have condensed out of the original water batch. This is the cheapest form of purified water, so may be used for common cleaning procedures in the laboratory.
Deionized water is by far the most used pure laboratory water. It uses a chemical process to eliminate mineral salts from the water to be used. The resins involved in the filtration process are specially made filters, which use an ion-exchange method to remove these harmful minerals. Continuous deionization can be achieved with electrodeionization, which uses similar resins, but are electrically charged to remove particles from the flowing water. This method is the most commonly used, as fresh pure water is always available to the laboratory from the community source, without the need to purchase water by the drum.
Reverse-osmosis water purification is another method for supplying the scientific laboratory with pure water. This method is similar in osmotic filtration, yet it uses high pressures forced upon the semi-permeable membrane to filter out undesirable particulates. This method, along with a pre-filtration of a sediment filter, which can be a cotton-wound filter, can reduce the amount of contaminants in the water to be used by the laboratory.
Carbon filtration is another simple method for providing laboratory pure water. This filtration method uses a block of dense carbon to trap particulates measuring down to the micron sizes. It also can remove chemical molecules and bacteria. A good system forces water to be filtered through a very dense carbon block, resulting in very clean and clear water.
The best method to assure complete pure laboratory water is to combine two or more of the above processes in a continuous filtration process. Using distilled water first, sent through a carbon block filter, then a deionization process, the water would be most assuredly pure enough for the exacting standards of any laboratory. If sterile water is also needed, an ultraviolet light sterilization unit can be used in conjunction with the other filtration processes to eliminate any stray bacteria from the water system.
Laboratory pure water is needed in a variety of sensitive testing and experimental processes. These easy to set up methods can be the cost effective way to eliminate contaminants from your laboratory water.
