Membrane filters are widely used methods of laboratory analysis for samples of drinking water, water for process use, industrial waste, etc. They are also commonly used for the analysis for pharmaceuticals and life science research.
Membrane filters consist of two parts: the membrane itself and the filter holder, also called a membrane box. The membrane is the actual filtering material, while the holder is used to secure it and protect it from being damaged or contaminated.
The membrane filters typically used in laboratories are made out of thin, flat sheets of cellulose or synthetic materials such as PTFE, polysulfone, or polypropylene. The thickness and porosity of the membrane depends on the molecule size and properties of the sample being analyzed.
Most membrane filters come in pre-cut pieces of various shapes and sizes, and the membranes can be customized to fit the specific requirements of the user. Membrane filters are also available in different shapes, such as discs, circles, squares, and round.
The filters may be suspended in a solution or mounted on a support frame for laboratory use, depending on the nature of the application. Membrane filters are generally supplied dry and must be moistened with a solvent such as water or a buffered solution prior to use.
Membrane filters are used in a variety of ways. For example, they can be used for the collection and concentration of liquid samples prior to analysis. This enables the user to obtain a smaller concentration of analytes compared to collecting a sample directly from the source.
Another method of use is for clarification. This involves passing a sample through a membrane filter to remove particles and suspended solids. The filtered product is then analysed for microbiological organisms, turbidity, color, and the presence of foreign material.
The membrane filters are also used in liquid chromatography for the analysis of close-range homologues. They are specifically designed for the separation of molecules of similar size from a sample solution. This is done by partitioning the molecules through the pores of the membrane.
Filters of a specific porosity or material characteristics can also be selected to match the specific gradients of different sample components, to improve the resolution of the separation.
Applications such as filtration, clarification, and chromatography require the use of membrane filters and membrane boxes. Both the membrane filters and the membrane boxes are important components of any laboratory analysis.
Membrane filters are a simple and economical way of ensuring that laboratory samples are free of suspended solids or particles, while the membrane boxes enable the secure storage and transportation of the delicate membrane filters. With careful selection and use, membrane filters and membrane boxes can improve the accuracy and efficiency of laboratory analysis.
