Conventional filter paper is generally divided into quantitative filter paper and qualitative filter paper, with strong absorption of liquids. The main components of filter paper are fibers, namely C, H, O, and small amounts of other elements. Which filter paper to choose depends on your experimental needs. If you need to weigh, generally choose quantitative filter paper, otherwise choose qualitative filter paper. Common filter papers are divided into slow, medium, and fast. The quality of the filter paper mainly depends on the purity of the cotton fiber. It is best not to have additives. HAWACH’s filter paper classification will be finer, with corresponding pore size. The pore size of slow filter paper is about 2.5-5 μm, the pore size of medium-speed filter paper is 8-11 μm, and the pore size of fast filter paper generally corresponds to 20-25 μm.
At HAWACH, the qualitative filter paper has 7 grades, BIO 91 (PbSO4), BIO 113 ( Fe(OH)3), BIO 6 (3μm), BIO 5 (2.5μm), BIO 4 (20μm), BIO 2 (8μm) and BIO 1 (11μm). The quantitative filter paper has five different grades, BIO 40 (8μm), BIO 41 (20-25μm), BIO 42 (2.5μm), BIO 43 (16μm), and BIO 44 (3μm). Today, HAWACH will focus on quantitative filter paper and discuss each quantitative filter paper grades. There are two shapes available, square and round, and different sizes can be chosen based on your specific demands.
Different grades of quantitative filter paper
HAWACH’s quantitative filter paper is available in three forms to meet your special needs. Ashless: Very pure filter paper, ideal for analytical filtration.
Hardened Ashless: As the name suggests, this filter paper contains an extremely low ash content and a hard surface makes it suitable for most filtration processes. Acid hardening increases its wet strength and chemical resistance. Each quantitative filter paper grades takes into account filtration speed and particle retention.
Hardened low ash grade: This filter paper is especially suitable for Buchner funnels because of its high wet strength and chemical resistance, the strong acid treatment removes trace metals, resulting in a hard smooth surface that makes the sediment easier to recover. Its properties including high strength wet and chemical compatibility are similar to hardened ashless grades of filter paper.
It’s for conventional filtration, medium low rate, and particle retention, which is used for specific gravity analysis, filtration of solutions, and sampling of air pollution before atomic absorption spectrophotometry. As primary filter paper for separation of solids from aqueous extracts in soil analysis, in quantitative milk composition analysis, as pure analytical grade clean filtration prior to atomic absorption spectroscopy. It is also used for high-purity collection of residual elements and radionuclides in the atmosphere, or as an impregnated filter paper to collect acidic and alkaline gases in the atmosphere, total arsenic content in food and feed, nitrate in forage grass, oxalic acid in canned vegetables, chemical fertilizers boron content, etc.
BIO 41: 20-25μm fastest ashless filter paper, recommended for analytical processes such as aluminum hydroxide or ferric hydroxide. Filtration of large particles or gel precipitates and determination of gaseous compounds at fast flow rates in quantitative air pollution analysis.
BIO 42: Medium-speed filter paper that retains the smallest particles in 2.5μm HAWACH fiber filter paper. It’s commonly used in the analysis of precipitates such as barium sulfate, metastannic acid, and calcium carbonate.
BIO 43: 16μm medium speed filter paper for sample collection in food analysis, soil analysis, air pollution monitoring, and inorganic analysis in the construction, mining, and steel industries.
BIO 44: 3μm regardless of size, Grade 44 has a lower ash content than other filter papers in this series. Small particles are collected slightly less efficiently than the Grade 42, but the flow rate is faster.