High-performance liquid chromatography (HPLC) is a powerful analytical technique used to separate, identify, and quantify the components of a sample mixture based on their chemical properties. It is widely used in many fields, including pharmaceuticals, biotechnology, environmental analysis, and food industry.
In HPLC, the sample is injected into a column packed with stationary phase material, and a mobile phase (or eluent) flows through the column to carry the sample components through the system. The stationary phase can be made up of various materials such as silica gel, alumina, or polymer-based resins, and the mobile phase can be a single solvent or a mixture of solvents.
The choice of mobile phase and stationary phase is critical for achieving the desired separation. The mobile phase is usually composed of water, an organic solvent such as methanol or acetonitrile, or a mixture of these solvents. The choice of solvent depends on the nature of the sample and the stationary phase.
Ultra-pure water is a commonly used solvent in HPLC because it is free of impurities that could interfere with the separation process. Impurities such as salts, ions, and organic compounds can lead to peak broadening, poor resolution, or even loss of separation. Therefore, it is essential to use ultra-pure water to prepare the mobile phase and to dilute the samples.
The term "ultra-pure water" refers to water that has been treated to remove all impurities to the highest possible degree. This level of purity is achieved by a combination of physical and chemical processes, including reverse osmosis, deionization, and distillation.
Reverse osmosis is a process that uses pressure to force water through a semipermeable membrane, removing contaminants and impurities. Deionization is a process that uses ion-exchange resins to remove ions and minerals from the water, and distillation involves boiling the water and collecting the resulting vapor, which is condensed to produce pure water.
Once the water has been purified, it is necessary to maintain its purity by storing it in clean, sterilized containers and filtering it immediately before use to remove any remaining particles, bacteria, or other microorganisms.
In summary, ultra-pure water is essential in HPLC as it ensures that the mobile phase and samples are free of impurities that could interfere with the separation process. It is produced using a combination of physical and chemical processes and is stored and handled carefully to maintain its purity.