Water is an often overlooked but vital reagent in the laboratory. What kinds of water are in the laboratory? What level can you achieve? What are the requirements for water in different experiments?
Types of common water in the laboratory:
1. Distilled Water:
The most commonly used type of water in the lab is cheap but extremely energy-intensive and slow, and the application will gradually decrease. Distilled water can remove most of the pollutants from tap water, but volatile impurities cannot be removed, such as carbon dioxide, ammonia, silica, and some organic matter. Fresh distilled water is sterile, but the bacteria are easy to reproduce after storage; In addition, storage containers are also very particular, if non-inert matter, the formation of ions and vessels can precipitate a secondary pollution.
2. Deionized Water:
Application of anion and cation ion exchange resin to remove the water, but there is still a soluble organic matter in water, can effect to reduce the pollution of ion exchange column, deionized water storage is also easy to cause bacteria breeding.
3. Reverse osmosis Water:
Anti permeation and overcome the many shortcomings of distilled water and deionized water, using reverse osmosis technology can effectively remove salt dissolved in water, colloid, bacteria, virus and bacterial endotoxin and most of the impurities such as organic matter, but different manufacturer production of reverse osmosis membrane had a great influence in the quality of the water seepage.
4. Ultra-pure grade water:
The standard is water resistivity was 18.2 M Ω - cm. However, the ultra-pure water is not the same as TOC, bacteria, endotoxin and other indicators. According to the requirements of the experiment, such as cell culture is required for bacteria and endotoxin, while HPLC requires low TOC.The standard is water resistivity was 18.2 M Ω - cm. However, the ultra-pure water is not the same as TOC, bacteria, endotoxin and other indicators. According to the requirements of the experiment, such as cell culture is required for bacteria and endotoxin, while HPLC requires low TOC.
Common indicators of water quality assessment:
1.The resistivity (electrical resistivity) :
Measure of the laboratory water conductivity unit is M Ω - cm, with the decrease of inorganic ions in the water resistance increase value increases gradually, the laboratory of ultrapure water standard: resistivity for 18.2 M Ω - cm.
2.Total Organic Carbon (TOC) :
The concentration of carbon in the water reflects the content of organic compounds in the water oxidized, and the unit is PPM or PPB.
3.Endotoxin:
The cell wall fragments of the polysaccharide of gram-negative bacteria, also known as the "hot primitive", unit cuf/ml
