Deionized (DI) water is an extremely versatile chemical and is essential for biomedical and chemical laboratories. Whether used as a base liquid for making cell culture media or as a diluent in a chemical reaction, practically every laboratory utilizes large volumes of DI water. Similarly, deionized water is also commonly found in the semiconductor industry in California, where it can be used to clean silicon wafers without damaging them.
But, laboratory managers and purchasing officers may not be familiar with why deionized water is any different from normal water or other chemicals with neutral pH. Furthermore, it may be confusing to choose between different DI water products which claim to be catered toward different purposes because the differences between them may be unclear. Making a smart purchasing decision—and giving the lab what it needs to succeed—will require a firm understanding of DI water as a reagent.
Deionized water is water which has been purged of minerals, trace elements, dissolved salts, anions, and other ions such that fewer than 0.1% of the original ions remain. Purging these contaminants from the water creates a chemical which is suitable for sensitive applications which would be disrupted by the presence of ions. For example, within a biomedical laboratory, using deionized water as a base fluid to create cell culture media ensures that the minerals and nutrients added to the media to nourish the cells are known and defined quantities rather than being added in addition to the variable quantity of minerals which would be in the water otherwise.
In effect, using DI water guarantees that the results of an experiment will reflect the experimental conditions rather than unexpected mineral content and ionic properties of the water used as a reagent in the experiment. As such, deionized water helps to minimize potential confounding variables in experiments. It’s also an effective fluid for washing away other polar chemicals without leaving any trace of contamination behind on the surface being washed.
Deionized water is produced in several different purities. These purity ratings correspond to the number of remaining ions in the final deionized water product. While higher purity indicates that a higher number of ions have been removed, in practice it is impossible to create a deionized water product that is 100% free of ions. The two most important ratings are standard deionized water and HPLC-grade deionized water.
Standard deionized water is suitable for the vast majority of lab applications which are sensitive to the presence of ions. In other words, standard deionized water is ion-free to the point where the impact of the remaining ions on the primary variables in most experiments is highly unlikely to be detectable. For the most sensitive of applications, such as in common analytical chemistry techniques like high-performance liquid chromatography (HPLC), the standard level of purity is not sufficient.
HPLC is exquisitely sensitive, which means that standard DI water will still have traces of ions which will disrupt the readout of the HPLC machine and prevent any analysis from being performed. Furthermore, the traces of ions in normal DI water can accumulate within the HPLC machine, thereby causing the machine’s readings to drift over time, potentially becoming inaccurate. As a result, there is an even higher standard of DI water, dubbed HPLC-grade deionized water. HPLC-grade DI water is suitable for less sensitive applications as well, but using it in applications which do not require the higher standard of purity is somewhat wasteful, so most laboratories keep separate stores of each type of DI water.
Finding the right type of DI water for the laboratory requires working with a reputable supplier local to San Jose who can help with assessing the inventory needs for it and other reagents. When working with a supplier, the trouble of finding the right DI water solution is lightened, and essential lab personnel can spend more time working on their experiments.
For over 40 years, Lab Pro has been committed to providing superior quality reagents like deionized water to laboratories in California and worldwide. Come visit the biggest Lab Supply showroom in California, or contact us online or at 888-452-2776.