About Standard Grade and Wet Strength Grade of Qualitative Filter Paper

The HAWACH filter paper is made of high-quality cotton fiber, with a cellulose content of more than 98%. Cellulose filter paper is mainly used for ordinary filtration, and the smallest particle interception can reach 2.5μm.

HAWACH provides a variety of filter papers with different flow rates to satisfy the majority of laboratory users. Compared with the flat filter paper of the same model, the folded qualitative filter paper speeds up the flow rate and increases the load capacity.

Standard grade of qualitative filter paper

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BIO 1: 11μm
Filter paper disc BIO 1 is a chemical analysis filter paper that is widely used in the world and has a long history. It has a medium retention capacity and flow rate. The specifications range from 10 mm to 500 mm diameter discs and 460/570 mm rectangles. It is also separated by traditional qualitative analysis of sediments, such as lead sulfate, calcium oxalate (hot), and calcium carbonate, which are cellulase activity, drilling fluid activated clay, protective cloth resistance, and standard filter paper for penicillin determination. It is widely used for simple qualitative analysis and separation in teaching.

In the field of air pollutant monitoring, there are discs and rolls available. Atmospheric dust is collected from the atmosphere and the degree of pollution is measured with a photometer. In gas detection, the filter paper is infiltrated with a color-developing agent and quantified by light reflection. The latest application of grade 1 filter paper is as a microfluidic chip substrate, leading the development direction of modern analytical technology.

BIO 2: 8 μm
The Grade 2 filter paper is slightly stronger than Grade 1, but the filtration time is relatively longer (that is, the filtration speed is relatively slower), and it is more adsorbing than Grade 1. In addition to the ordinary filtration of 8μm particles, its additional adsorption performance also comes in handy, such as intercepting soil nutrients in plant growth experiments, monitoring special pollutants in the air and soil, etc., or standard analysis filter paper for determination of gelatin, feed, meat, medicines, vitamins, tomatoes, infant milk powder, etc.

BIO 3: 6 μm
The thickness is twice that of Grade 1. The load capacity is good, the particle retention is small, and more sediment can be obtained without clogging. It is frequently used in the Buchner funnel, because of its excellent wet strength. Its high adsorption performance can be used as a sample carrier, which is the standard filter paper for the determination of piperazine in feed and sorbic acid in dairy products.

BIO 4: 20-25 μm
The Grade 4 filter paper has a very fast filtration rate, is able to trap coarse particles and colloidal precipitates such as iron hydroxide and aluminum hydroxide very well, which is frequently used in biological or organic extracts rapid filtration. When monitoring high-velocity air pollution, if it is not necessary to trap fine particles, it can also be used to determine standard analysis filter papers such as corn syrup, dairy products, disinfectant spore activity, and 3-chloro-1,2-propanediol in food.

BIO 5: 2.5μm
Within the qualitative range, the particles are retained to the greatest extent. It is possible to collect small precipitates encountered in chemical analysis. The flow rate is slower and it’s suitable for chemical analysis, clarification of suspended solids, and water/soil analysis.

BIO 6: 3 μm
Its flow rate is twice that 2.5μm filter, with the same particle retention. It’s often designated for boiler water analysis.

Qualitative filter paper-wet strength grade

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This type of filter paper is very tough and has high wet strength without introducing obvious impurities in ordinary qualitative applications. However, the resin contains nitrogen, so it should be noted that it cannot be used for Kjeldahl nitrogen determination.

BIO 91: 10μm
It’s a kind of ordinary wrinkle filter paper. 10 micron filter paper is widely used for sucrose content analysis of sugarcane and routine sample filtration in pharmaceutical factory laboratories, as well as the filtration of the gold mine-cyanide reaction solution, electroplating solution, etc.

BIO 93: 10μm
It can be humidified with a ventilator or other applications requiring high strength. It adopts convenient packaging, which can be directly hung on the wall or placed on the workbench and can also be placed vertically or flat on a shelf, which is convenient to take out one by one. The large and small packages are clearly marked with the size and quantity.

BIO 113: 30μm
It has a very high load capacity, suitable for filtration of large particles or gelatinous precipitation. There are wrinkles on the surface, which are thick in qualitative filter paper and are often used to filter resin solutions.

BIO 114: 25μm
It is suitable for filtering crude products or gelatinous sediments. The surface is smooth and easy to collect deposits. It can be used for engine oil filtration performance measurement, etc.