Four Aspects to Be Considered When Choosing Filter Paper and How to Use It

Chemical analysis filter paper (qualitative filter paper, quantitative filter paper) is made of high-quality high-grade cotton, using modern and unique papermaking technology and advanced papermaking equipment. It is a kind of high purity, uniform organization, and has a certain filtering speed and certain strength cotton paper. They are widely used in scientific research, industry, agriculture, medicine and health, environmental protection, and other departments for qualitative and quantitative layer analysis and testing. Here are four points to be considered when selecting filter paper.

Four aspects when selecting filter paper

The composition of most filter paper disc is cotton fiber, and there are countless small holes on the surface for liquid ions to pass through, while larger solids cannot pass. This property can satisfy the separation of liquid and solid substances mixed together. Different filter papers have different functions and characteristics, which can meet the filtration problems of a variety of solutions. Users need to pay attention to four aspects when selecting filter paper types. These four points are hardness, filtration efficiency, capacity, and applicability.

Hardness: Quantitative filter paper will become wet during filtration. Consider the tougher filter paper after wet water if for long-term filtration experiments. Qualitative filter paper generally has high adsorption capacity, smooth surface, high wet strength, and a wide application range.

Filtration efficiency: The density and size of the pores on the quantitative filter paper affect its filtration efficiency. High-efficiency filter paper has both fast speed and high resolution. The finished qualitative filter paper has a relatively flat surface, uniform texture, high resolution, good results reproducibility, strong load capacity, good diffusion effect, very few impurities, and low background interference.

Capacity: The solid particles accumulated during filtration or the pores on the filter paper are blocked. Therefore, the denser the water seepage pores, the higher its capacity represents, and the more filter lines are allowed to be filtered.

Applicability: In addition to the normal filter papers, some are made by special processing steps. For example, when used in laboratory medicine to determine the nitrogen content in the blood, nitrogen-free filter paper must be used.

10 micron filter paper qualitative-filter-papers-bio-6 hawach-filter-papers-bio-6

How to use filter paper

The filter paper is usually used with the funnel and a flower-shaped folding method is frequently used.
1. Fold the filter paper twice in a row to form a funnel with a 90° central angle.
2. Form a funnel by pressing one side folded filter paper into three layers and one side one layer.
3. Pour some clean water into the mouth of the funnel to make the soaked filter paper stick to the inner wall of the funnel, and then pour out the remaining clean water and set it aside.
4. Place the funnel with the filter paper on the funnel stand for filtering (such as the ring of the iron stand), place the beaker or test tube under the funnel neck, and make the tip lean against the wall.
5. When injecting the liquid to be filtered into the funnel, hold the liquid beaker in the right hand and the glass rod in the left hand. To make sure the cup mouth is close to the glass rod, with the glass rod lower end close to the funnel third layer’s lower surface. Then the filtered liquid flows out along the cup’s mouth. Make it flow into the funnel by tilting the glass rod.
6. Through the filter paper liquid flows down the funnel neck. It’s time for the operator to check whether the liquids flow down the cap wall and enters the bottom. Or, to make sure the funnel tip is attached to the breaker wall firmly.