Lab Equipment: Water Purification Systems and Methods of Purification

Water purification lab equipment ensures the quality of the water used in the lab to perform successful and reliable tests. Many water purification systems can handle a range of applications from basic buffer preparations to highly sensitive protocols such as HPLC, PCR, or uses that require precise TOC removal and measurement. Other systems can be used for rinsing lab glassware, supplying autoclaves and ultrapure water systems, and preparing and diluting buffers, reagents, and media.

Water grade standards are classified as Type 1 (ultrapure water, 18.2 MΩ), Type II (pure water, 1 to 15MΩ), Type III (reverse osmosis water) and Type IV (cartridge/filter system water). Water feed sources can range from tap water to distilled, deionized, or reverse osmosis (RO) water).

Methods of Purification:

Adsorption: Activated carbon bonds with the chlorine and organic materials in feedwater to immobilize and remove these impurities

Deionization: The removal of ions and minerals by synthetic ion exchange resins. Cation resins remove positively charged ions; anion resins remove negatively charged ions

Distillation: The process in which water is heated to a gaseous state and recondensed in a separate vessel

Filtration: Use as a pretreatment or a stand-alone treatment. Water passes through a filter of specified porosity at normal line pressures. The filter retains most particulates, with water passing through

Reverse osmosis (RO): Use primarily as a pretreatment. Equal amounts of pure water and saline solution are separated in a U-tube by a semipermeable membrane. When external pressure is applied to the saline side, the semipermeable membrane allows water to pass through while salts are concentrated and flushed down a drain

Ultrafiltration: Use for removing pyrogens and bacteria. Under pressure, water is forced through a membrane with a pore size smaller than 0.005 μm. Particulates are retained, with only pure water passing through

Ultraviolet (UV) oxidation: UV light (at <280 nm) passes through the water destroying bacteria, viruses, and trace organics