Sterile and Individually Packaged for Colony Counting
Sterile, individually packed filters have long become standard for routine microbiological quality control because of the user benefits they offer.
They are pre-sterilized and ready-to-use, and save preparatory time. As they are individually packed, they avoid the possibility of contamination of remaining filters in opened packs and conform to GLP – with filter identification and lot number printed on each individual envelope.
Cellulose nitrate membranes are mixed cellulose ester membranes containing cellulose nitrate and cellulose acetate, a material which assures effective retention with high-flow rates and optimal colony growth. The printed grid with a size of 3.1 x 3.1 mm makes the counting easier, especially for higher bacteria counts and for microcolonies, but neither inhibits nor enhances growth. The various filter colours allow the best contrast to the colonies and particles, for easy and reliable quantification and identification.
The standard membrane filter for microbiological analysis is a 0.45 µm filter. One special variant is the High-Flow membrane. It provides 30% higher flow rates in comparison to traditional 0.45 µm membranes due to the special pore structure, which thus allows shorter filtration times. Especially for the detection of E. coli, High-Flow membranes are highly recommended as they achieve the best growth promotion results.