Several Main Differences Between Quantitative and Qualitative Filter Papers

Filter paper is mostly made of cotton fibers and is made in different ways depending on the application. Because it is made of fibers, it has numerous small holes on its surface for liquid particles to pass through, while larger solid particles cannot. In general, filter papers can be classified as qualitative or quantitative. In analytical chemistry applications, when filtering inorganic compounds to separate out precipitates, the residue collected on the filter paper can be used to calculate the loss rate during the experiment.

Qualitative filter papers are only suitable for qualitative analysis because filtration produces more cotton fibers; quantitative filter papers, especially ashless filter papers, are effectively resistant to chemical reactions through special treatment procedures, and therefore have fewer impurities and can be used for quantitative analysis. The ash content of cellulose filter paper is determined by weighing the residue of combustion under air at 900°C. The minimum ash content is critical to the weight method and is a valid measure of general purity levels. The main role of quantitative analytical filter paper is used for filtration after the need for an ashing weighing analysis test, the weight of ash after ashing each filter paper is a fixed value; qualitative filter paper is used for general filtration role, that is, qualitative chemical analysis and the corresponding filter separation.

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Filtration speed difference

1. Fast filter paper, because the paper is loose, the spot is easy to spread, suitable for samples with larger Rf value and greater viscosity of the unfolding agent
2. Slow filter paper, the spot is not easy to spread, suitable for samples with smaller Rf value and less viscosity of the unfolding agent, but the unfolding time is longer
3. Medium-speed filter paper in between

Color difference

1. Quantitative filter paper: fast: black or white paper strip; medium speed: blue paper strip; slow speed: red or orange paper strip
2. Qualitative filter paper: fast: black or white paper band; medium speed: blue paper band; slow speed: red or orange paper band

Quantitative filter papers

HAWACH quantitative filter papers are designed for sample preparation in weight analysis and instrumental analysis. They are available in three forms to meet your specific needs.
Ashless grade: Very pure filter paper, ideal for most major analytical filtration processes.
Hardened Low Ash: Treated with strong acids to remove trace metals, producing high wet strength and chemical resistance, these filter papers are particularly suitable for use in Brinell funnels, where the hard, smooth surface of the paper makes it easy to recover precipitates.

Hardening without ash:< very low ash content, acid hardening increases wet strength and chemical resistance, making it suitable for many filtration processes.
These filter papers are mostly used together with instruments such as filter funnels and Brinell funnels. Before use, the filter paper should be folded into a suitable shape, and a common method is to fold the filter paper into a flower-like shape. The higher the degree of folding, the higher the surface area and the better the filtration effect, but be careful not to break the filter paper by overfolding. Place the glass rod of drainage on the multi-layer filter paper with even pressure to avoid the destruction of the filter paper.

Qualitative filter papers

HAWACH qualitative filter paper generally uses gravity filtration, using filter paper to retain solid-phase particles and solid-liquid separation, filter paper is usually used in a single-layer or multi-layer fragrance. Filter paper has natural mechanical strength and certain toughness, if you need to speed up the filtration speed, the filter paper can be folded several times (such as two layers of filter paper stacked into a fan or tie type), which can significantly increase the filtration speed. In the air pump filtration, according to the size of the pumping force in the funnel stack 2-3 layers of filter paper, or first pad a layer of dense filter cloth, then put the filter paper filter. Highly corrosive concentrated nitric acid and concentrated sulfuric acid solution should not be filtered by ordinary filter paper, special filter paper should be used. Qualitative filter paper is also commonly used to clean the test bench and clean and wipe the laboratory equipment and tools.

Qualitative filter paper is mainly used for industrial production and teaching and research because of its smooth surface, strong loading capacity, good filtration effect, high wet strength, and ideal particle interception effect. Qualitative filter paper can also be divided into two categories according to the shape, including qualitative square large sheet filter paper: mainly used for industrial filtration, it is not analytical filter paper, but paper filter material, from the coarse filtration of Western pharmaceutical solutions, coarse filtration of proprietary Chinese medicine, fine filtration, to chemical product filtration, electroplating industry filtration, etc.: and another qualitative circle filter paper; mainly used for dry qualitative chemical analysis and the corresponding filtration separation, is a laboratory necessity.