Water is one of the most commonly used solvents in liquid phase experiments, such as purified water, distilled water, ultrapure water, etc. But do you know how to choose the right water?
Basic Structure of Water
A water molecule (H2O) is formed by one oxygen atom bending bonds two hydrogen atoms. As the centers of positive and negative charges are not consistent, water molecules belong to polar molecules. When two water molecules coexist, they will be combined by electrostatic interaction with hydrogen bonds to attract each other and maintain a certain distance. Whilst one water molecule can combine with four water molecules at the same time to form a crystal structure.
Possible Impurities in Water
Soluble inorganic substances: inorganic salts, dissolved gases, heavy metals, hardness components (calcium, magnesium, etc);
Soluble organic matter: lignin, tannin, humic acid, endotoxin, RNA decomposing enzyme, pesticide, trichloromethane, environmental hormone, interfacial active agent, organic solvent;
Microparticles: rust, colloid, suspended substance, solid particles;
Microorganisms: bacteria, algae.
What’s in the Water?
Particles will wear pumps, especially our sealing loop and plunger rod. For our injectors, the particles will also wear them. In addition, particles will block columns and pipes, resulting in increased pressure. Particles will also behave as another stationary phase that may alter the composition of samples.
Organics in ultrapure water may affect the resolution of the peak, leading to ghost peaks. It may also change the selectivity of stationary phase and affect chromatographic baseline.
The change of ion concentration will affect the separation result, and some ions that absorb ultraviolet light will affect the peak, too. Some corrosive ions even reduce the lifetime of high-pressure infusion pumps and other accessories.
Colloids will be irreversibly adsorbed on the stationary phase, affecting the resolution of columns.
Microbes will block columns, and their metabolites will increase organics, particles and other pollutants.
Common Water in Lab
The common water in the laboratory: purified water, deionized water, ultrapure water.
With lowest level of purification, its conductivity is usually between 1-50μs/cm. It can be made by reverse osmosis or single distillation of weak basic anion exchange resin. Typical applications include cleaning of glassware, high pressure sterilizer, constant temperature and humidity laboratory boxand or water used in cleaning machine.
Conductivity is usually between 1.0–0.1μs/cm. It formed by mixed bed ion exchange with strong anion exchange resin. It has relatively high level for cleaning organics and bacterial contamination, which can meet a variety of needs, such as cleaning, preparing analytical standard samples, preparing reagents and diluting samples.
This level of ultrapure water is close to the theoretical purity limit in terms of resistivity, organics content, particle and bacterial content. Usually we purify by ion exchange, RO membrane or distillation at first, then obtain the ultrapure water by ion exchange purification. Generally, the resistivity of ultrapure water can reach MΩ.18.2 cm, TOC<10 ppb, If filter out 0.1μm or smaller particles, bacterial content can be less than 1 CFU/ml. Ultra-pure water is suitable for various kinds of precision analysis experiments, such as high performance liquid chromatography (HPLC), ion chromatography (IC) and ion capture-mass spectrometry (ICP-MS).
Ghost-Buster II Column
● Optimized packing process, improved production method, better capturing effect and longer tolerance;
● Further upgrade the overall product design, greatly reduces the baseline fluctuations in the initial operation of the baseline fluctuations, drift and other situations;
● More compatible with high proportion aqueous phase gradient to shorten the running time in gradient program, and more stable baseline.
|06100-31008||Ghost-Buster Column Ⅱ||4.0×50mm||40MPa|
|06100-31016||Ghost-Buster Column Ⅱ||3.0×50mm||40MPa|
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