Overview Qualitative filter paper, the qualitative analysis filter paper is compared with quantitative analysis filter paper and layer praying qualitative analysis filter paper: it is a kind of paper with good filtering performance, loose paper, liquid has a strong absorption performance. Filter paper is often used as the filter medium in analytical laboratories to separate the liquid from solid.
Classification 1. Quantitative analysis of filter paper Quantitative analysis filter paper in the manufacturing process, after hydrochloric acid and hydrofluoric acid treatment, and through distilled water washing. Most of the impurities in the paper fiber are removed, so the residual ash content after burning is very little, which has little influence on the analysis results. Suitable for precise quantitative analysis.
2. Qualitative analysis of filter paper The types and specifications of qualitative analysis filter paper are basically the same as quantitative analysis filter paper, indicating fast, medium and slow speed.
However, it is not necessary to use quantitative and qualitative analysis of the filter paper on the packaging box to filter the precipitation. It should be noted that natural filtration is generally used to separate the liquid from the solid by using the filter paper and the ability to trap solid particles.
As a result of the mechanical strength and toughness of the filter paper are used as little as possible filtration method: if must speed up the filtration speed, in order to prevent filtration and lead to failure rate: in the air pump filtration, according to the size of the pumping force in the funnel put 2 ~ 3 layers of filter paper. When vacuuming, apply a dense press cloth and filter paper on top of it. Filter paper had better not filter hot concentrated sulfuric acid or nitric acid solution.
3. Qualitative analysis of filter paper by chromatography The qualitative analysis filter paper is mainly used as a carrier in the chromatographic analysis method for qualitative separation chromatography of the substance to be measured. There are two kinds of qualitative analysis filter paper of no. 1 and no. 3, and each type is divided into fast, medium, and slow. Qualitative filter paper aperture is irregular, usually qualitative filter paper pore is large, quantitative small.
What is the difference between a quantitative filter paper and a qualitative filter paper? Which instruments are applicable? The difference between quantitative filter paper and qualitative filter paper mainly lies in the ash content after ashing: qualitative filter paper does not exceed 0.13%; Quantitative filter paper is not more than 0.0009%. Note that the concepts of quantitative filter paper and qualitative filter paper are unique to cellulose filter paper and do not apply to other types of paper such as glass microfiber filter paper.
The USES of quantitative filter paper and qualitative filter paper are as follows: qualitative filter paper is used for qualitative chemical analysis and phase separation; The quantitative filter paper is used for quantitative analysis test by weight method and corresponding analysis test.
The choice of an appropriate filter paper can be made by considering the following four factors.
Hardness The filter paper will get wet when it is filtered. Some experimental steps of filtration for a long time should consider using the filter paper which is stronger after wet water.
Filtration efficiency The density and size of porous holes in filter paper affect their filtration efficiency. The efficient filter paper filtration speed is fast and the resolution is high.
Capacity The solid particles accumulated during filtration can block the holes in the filter paper. Therefore, the more dense the seepage hole is, the higher the capacity is, and the more filtering grain is allowed.
Applicability Some filter paper is made using special steps. In laboratory medicine, for example, a nitrogen-free filter must be used to determine the level of nitrogen in the blood.