Filtration

Filtration, in the laboratory, is the separation of two phases and can basically be of two types:

quantitative = when 80 to 99% of material passes from one phase to the other; quantitative-paper-example
quantitative = when the separation is more detailed, when dimensions of the matter to be passed from one stage to another are defined. example qualitative filtration

Filtration in fact means passing a certain amount of a fluid or gas through a porous film. The pore size is defined and in the passage of matter all suspended particles larger than this size are retained.

Filtration performance and characteristics

There are at least 4 parameters to take into account when making a choice for filtration:
The robustness of the membranes, purity, porosity and heat resistance.
The robustness must be measured and guaranteed for both longitudinal and lateral tear resistance. For more difficult applications, there are membranes reinforced with nylon.
Purity is guaranteed by the quality of the workmanship, which is carried out in clean rooms to provide perfect sterility.
Porosity is the effective value that allows a certain amount of fluid or gas to pass through the pores. The surface must be uniform.
Heat resistance must allow membranes to be autoclavable at temperatures of up to 180°C without undergoing visible deformation.

How to choose a filter membrane

First of all, it must be defined which liquid or gas is to be filtered. For example, hydrophilic membranes are used when working with aqueous liquids. On the other hand, when working with solvents, PTFE or Nylon membranes should be used.
When working with gases, hydrophobic membranes are recommended.
You must pay close attention to the chemical compatibility of the membrane with the substance to be filtered.
It is also important to check the maximum porosity required to achieve the desired results. The size of the suspended particles retained by the filtration must be taken into account.
Last but not least, in addition to temperature resistance where necessary, the necessary filtration surface area must be defined according to the quantity and density of the product to be filtered.
There are many variants on the market to meet all laboratory requirements.

Syringe Filters

Of the filtration-related products in the catalogue, syringe filters are disposable.
One of their most necessary characteristics is that they retain as little product as possible and operate at the highest degree of purity to avoid contamination.
Each package is marked with precise codes identifying its purity, porosity and constituent materials.
Syringe filters are distinguished according to the amount of sample volume they have to work with: from less than 2 ml up to over 1 litre.
The filters are made from different materials, possessing specific properties and porosity for each type of processing.

Vacuum Filtration

Vacuum filtration is mainly used in microbiology and analytical processes that require separation of particles suspended in a liquid, such as bacteria or precipitates.
The filter is placed over a container, usually a beaker, which retains the particulate. The liquid part, on the other hand, passes through the membrane and collects in a filter flask. This is done either directly or by means of a filtration ramp.
The use of a vacuum speeds up the filtration and shortens the process time.