Aids for ananalytical and biological laboratories

The ultrafilters available under the trade name Pragopor are microporous membranes made of nitrocellulose. The porous structure of the filters is created by a lamellated system of small voids which nevertheless enables separation even of the tiniest particles.
 

• almost entire filtration performance
• good chemical durability against most acids, alkalis and some solvents
• very low weight and negligible hygroscopicity
• negligible ash residue after burning (0,03 – 0,05 % by weight)
• good retention capability of the filters for the particles, clogging of the pores and, consequently, the final inactivation of the filters being a very slow process
• very smooth surface of a chalk-white colour
• possibility of making the filters translucent and easy mineralization and dissolution of the filters in some organic solvents if required
• possibility of a treatment of the substance retained on the filter for its examination by electron microscopy

The membrane ultrafilters are useful instruments in many fields of laboratory work, e.g.:

• microbiology, pharmacy, hygiene and epidemiology either for cultivation of germs or for their proof and identification through microscopy
• in virology for sterilization and determination of the germs suspensions
• for the determination of the bacterial pollution of gases and liquids
• for the separation of solid particles from both gases and liquids
• for water analysis as well as many other physical and chemical instrumental methods

The Pragopor membrane ultrafilters are manufactured in the shape of small sectors of the diameter 24 – 150 mm (most often 35 mm and 50 mm) or as square-shaped foils of the size 0,5 x 0,5 m in the particular sorts designated by number 1 – 11, the number being assigned to the respective pore size:

Filtration sheets are made of the same substance as the Pragopol microporous membrane ultrafilters being created by the gelatination process of the colloid solutions of nitrocellulose but applied onto the textile substrate. The structure of the tiniest voids within the filtration substance which causes its high porosity and retention capability remains the same but the mechanical strength being substantially enhanced. Like the Pragopor membrane ultrafilters, the filtration sheets feature a good resistance against most acids and alkalis and some solvents. As for the other features, both types of filters are fairly the same.

The filtration substance may be used in many fields but, unlike the membrane ultrafilters, are rather preferred in filtration and separation processes of solid particles from liquids and gases and, to a lesser extent, for some methods of chemical analysis.

The filtration sheets are available in five sorts according to the specified pore size: