Filter paper chromatography uses filter paper as an inert support. The filter paper fiber has a strong affinity with water and can absorb about 22% of water, and 6 to 7% of the water is hydrogen-bonded to the hydroxyl group of cellulose, which is difficult to remove under normal conditions. The affinity of filter paper fibers and organic solvents is very weak, so general paper chromatography uses the binding water of filter paper fibers as the stationary phase and the organic solvent as the mobile phase.
Partitioning is continuously performed between water and organic phases. Part of the sample moves with the mobile phase and enters the solute-free zone. At this time, it is redistributed, and part of the solute enters the stationary phase (water phase) from the mobile phase. Various parts are continuously distributed based on the respective distribution coefficients, and move along the mobile phase, to make the material separated and purified.
Filter paper classification
Generally, filter paper can be divided into qualitative and quantitative. In the application of analytical chemistry, the residue collected on the filter paper after the separation of inorganic compounds by filtration to separate the precipitate can be used to calculate the loss rate during the experiment. After the qualitative filter paper is filtered, more cotton fibers are generated, so it is only suitable for qualitative analysis. In the production of quantitative filter paper, the pulp is treated with hydrochloric acid and hydrofluoric acid and washed with distilled water to remove most impurities in the paper fiber.
So there is little residual ash after burning, and it has almost no effect on the analysis results, which is suitable for precise quantitative analysis. After ashing, the ash amount is less than 0.0009%.
Grade: Filter papers are often classified by grade, with each grade representing a specific range of properties. The grade is typically denoted by a number or a combination of letters and numbers.
Particle Retention: Filter papers are classified based on their ability to retain particles of a certain size. Common designations include coarse, medium, and fine, indicating the particle size range the paper can effectively retain.
Porosity: Filter papers may be classified by their porosity, which influences the flow rate of liquids through the paper. Common categories include fast, medium, and slow, indicating the speed of filtration.
Basis Weight: Filter papers are often classified by their basis weight, which is the weight of a standard-sized sheet. Light, medium, and heavy basis weights are available to suit different filtration needs.
Material Composition: Filter papers can be made from various materials, such as cellulose, glass fiber, or synthetic fibers. The material composition can impact chemical compatibility and strength.
Qualitative vs. Quantitative: Filter papers are classified as qualitative or quantitative based on their suitability for qualitative or quantitative analysis. Quantitative filter papers are designed for gravimetric analysis.
Ash Content: Quantitative filter papers are sometimes classified based on their ash content, which is important for applications where low ash content is critical, such as in analytical chemistry.
Thickness: Filter papers vary in thickness, and this property can affect their porosity and filtration efficiency. Thin papers may be suitable for fast filtration, while thicker papers may provide better particle retention.
Diameter or Shape: Filter papers are available in various diameters or shapes to fit different filtration apparatus, such as filter funnels or filter crucibles.
Application-Specific Papers: Some filter papers are designed for specific applications, such as those treated for gravimetric sulfur analysis, water testing, or biological sample filtration.
Filter paper is a filtering tool commonly used in chemical laboratories. The common shape is round and mostly made of cotton fibers. HAWACH can provide both round and square filter papers. Round filter paper has conventional specifications of 70, 90, 100, 125, 150, 180, 55, 47, and 185, and also unconventional sizes of 240, 270, and 300. For the square sizes, there are two specifications, 60×60 and 41×45. Welcome to contact HAWACH (hawach.com or email@example.com)to learn more details.
Notes before the use of filter paper
Filter paper is a scientific tool that can effectively filter media and can be divided into two types. Qualitative analysis filter paper generally has a large amount of residual ash compared with quantitative. It is only used for general qualitative analysis and for filtering sediment or suspended matter in solution, and cannot be used for mass analysis. No matter for the qualitative or quantitative filter paper, some notes should pay attention before use.
1. In general, it uses natural filtration, with the filter paper body and the ability to retain solid particles, to separate the liquid and solid; 2. Because the mechanical strength and toughness of the filter paper are both poor, try to use less filtration to filter. If the filtration speed must be increased, the filtration failure will be prevented to prevent the filtration. When the air pump is filtered, it can be stacked in the funnel according to the pumping force. Put 2~3 layers of filter paper, when vacuuming filtration, in the leak. First pad a layer of dense filter cloth, then put filter paper on it; 3. Filter paper is best not to filter hot concentrated sulfuric acid or nitric acid solution.