The Role of Filter Papers

The filter paper used in the analytical laboratory performs a strong absorption effect for liquids, which can separate the solution from the solid. The filter paper produced domestically could be divided into three types, including qualitative filter paper, and quantitative filter paper.

Qualitative Filter Paper

Qualitative filter papers generally have a large number of residual ash, which is only used for general qualitative analysis, sediment filtration or suspended solids in solution. However, it may not be used for mass analysis. Based on the speed of its filtration, the qualitative filter paper is classified as fast, medium and slow speed type with square and round shape. There are various sizes of it provided for selection.

Quantitative Filter Paper

The quantitative filter papers are applied for precise quantitative analysis. During its manufacturing process, the paper pulp is treated with hydrochloric acid and hydrofluoric acid in the first step. And then, it is washed with distilled water, which is supposed to remove most of the impurities in the paper fiber. Thus, there is only a tiny amount of residual ash contained after burning, which barely has an effect on the analysis results. The quantitative filter paper is only shaped in the round.