About the Three Grades of Lab Quantitative Filter Paper

HAWACH quantitative filter paper comes in three forms to meet your special needs: ash-free, hardened low ash, and hardened without ash grade.

1. Ash-free grade: Grade 40-44 <0.007%, Grade 589 <0.01%-very pure filter paper, ideal for most major analysis and filtration processes.
2. Hardened low ash: <0.015%, after strong acid treatment to remove trace metals, resulting in high wet strength and chemical resistance, these filter papers are especially suitable for Buchner funnels. The hard and smooth surface of the filter paper makes it easy to recover sediment.
3. Hardened without ash: <0.006%, very low ash content, acid hardening increases wet strength and chemical resistance. The hard surface makes these filter papers suitable for most major filtration processes.

Ash-free grade filter paper

Quantitative Medium Flow Filter Paper Grade: BIO-40
Ashless filter paper for regular filtration, medium flow rate, and particle retention. It is used to analyze the proportion of cement, soil, and metal components. As the main filter paper used to separate solid substances from the water phase extract in soil analysis, in quantitative milk component analysis, it is used as a pure analytical grade clean filter before atomic absorption spectroscopy. It can be acted as an impregnated filter paper to collect acidic and alkaline gases in the atmosphere, total arsenic content in food and feed, nitrate in the pasture, oxalic acid in canned vegetables, and fertilizer Medium boron content, and so on.

Quantitative Ashless Filter Paper Grade: BIO-41
The ashless filter paper with the fastest flow rate is recommended for analysis processes such as aluminum hydroxide or iron hydroxide. It is also used for the filtration of large particles or gelatinous sediments, such as the filtration of iron content in iron ore and magnesium content in magnesium ore. It is also often used for the determination of ambient air pollutants, such as suspended particulates and gaseous compounds (such as fluoride) and other samples, or filter the digestion solution for spectroscopy, chromatography, or mass spectrometry, such as the determination of picric acid turbidity, pectic acid in food, etc. This filter paper is also the matrix of standard tear test paper. The filter paper can be used in a disposable filter funnel. This convenient disposable 47 mm filter funnel has a maximum filtration capacity of 250 ml. The filter paper can be easily taken out for further analysis or culture.

Quantitative Laboratory Filter Paper Grade: BIO-42
The finest particle retention in all cellulose filter papers of HAWACH is the world standard for gravimetric analysis. It is commonly used for the determination of elemental content of minerals such as barium sulfate, metastannic acid, calcium carbonate, strontium carbonate, filtration of gasoline or organic solvents, and filtration preparation of spectral and chromatographic samples, such as atomic absorption method (AAS) determination of dilaurel in feed Determination of dibutyl tin acid content.

2.5 micron filter paper fast flow filter paper filter paper for laboratory use

Grade 43 filter paper
Its particle retention is twice as fast as Grade 40. Typical applications include food analysis, soil analysis, and fluorescence spectroscopy analysis after particle collection in air pollution monitoring. It is also used for inorganic analysis in the construction, mineral, and steel industries.

Grade 44 filter paper
The thin version of Grade 42 cuts finer particles, but the ash content of each sample is lower, and the flow rate is almost twice that of Grade 42.

Hardened low ash grade filter paper

The highest ash content of these filter papers is between the ash-free grade and the qualitative grade, especially suitable for Buchner funnel filtration. Its tough and smooth surface is easy to recover sediment. It is featured by wide chemical compatibility and high wet strength.

Grade 50 filter paper
It is the thinnest kind of HAWACH filter paper. It has a slow flow rate and good particle retention. It is currently the designated standard filter paper for drilling fluid determination worldwide and is widely used in oil and gas production fluid laboratories. The hardened surface effectively prevents the fiber from falling off, very suitable for vacuum qualitative or quantitative filtration of Buchner funnels and three-piece funnels. With very good wet strength, it can be processed in a wet state to scrape off the precipitate. In the field of the electronics industry, it is a carrier with almost no fiber shedding, which is suitable for integrated circuits. This level also provides a smearing pattern for wiping tests (for example, surface tests for radionuclide contamination).

Grade 52 filter paper
It is a hardened filter paper for conventional filtration, medium retention capacity and flow rate, tough surface.

Grade 54 filter paper
The fast flow rate and high humidity make this grade very suitable for rapid vacuum filtration to remove hard-to-filter coarse particles and filter colloidal precipitates, such as ethyl hydroxyquinine in feed.

Hardened without ash grade filter paper

These filter papers are acid-hardened, reducing the ash content to an extremely low level, and are known as the cleanest analytical filter papers in the world. The tough surface makes this type of filter paper suitable for a variety of stringent filtration steps. Each level takes into account filtration speed and particle retention.

Grade 540 filter paper
It is a hardened ashless filter paper for regular filtration, medium flow rate, and particle retention performance, which is commonly used in the analysis of the specific gravity of metal substances in acid/alkaline solutions.

Grade 541 filter paper
It is able to quickly filter large particles and colloidal precipitates in acidic or alkaline solutions for specific gravity analysis. Typical applications include determination of fiber in animal food, determination of gel in milk and cream, analysis of chloride in cement, and determination of chlorine and phosphorus in coal and coke. It is also used for the determination of soy protein in meat by enzyme-linked immunosorbent method and the determination of ascorbic acid by titration method. In terms of environmental air pollution, due to the high flow rate of the filter paper and the extremely low chemical background, it can be used for atmospheric particulate matter sampling and heavy metal element analysis, such as hexavalent chromium, lead, mercury, and arsenic, can be used.

Grade 542 filter paper
Under the required conditions, it has a high degree of retention of fine particles. It is strong, with slow flow rate and excellent chemical resistance. It is often used for the determination of specific heavy metals.