Microbial Limit Test MembraneCellulose Grid Membrane

Basic Overview

Definition: Grid membrane, also known as cellulose grid membrane or microbial limit test membrane, is essentially a sterilized microbial limit test disc membrane with a grid pattern.

Principle: It utilizes microporous membranes of different pore sizes to retain microorganisms from liquid samples while allowing the liquid to pass through. The membrane containing the retained microorganisms is then transferred to a suitable culture medium for incubation. By observing and counting the microbial colonies grown on the membrane, the microbial limit in the sample is determined.

Product Features

Diverse Materials: Main materials include mixed cellulose ester (MCE), cellulose nitrate (CN), and polyethersulfone (PES). Grid membranes made from different materials exhibit distinct characteristics. For example, mixed cellulose ester membranes offer good hydrophilicity and compatibility, cellulose nitrate membranes have high protein binding capacity, and polyethersulfone membranes provide excellent chemical stability and high-temperature resistance.

Various Packaging Forms: Available in both individual packaging and continuous packaging. Individually packaged grid membranes are convenient for single use and suitable for testing small sample volumes, while continuously packaged grid membranes are more appropriate for batch testing, improving detection efficiency. High microbial recovery rate.

Facilitates Colony Counting: The grid lines on the membrane aid in the identification and counting of colonies without affecting their growth, enabling more accurate and rapid quantification of microorganisms by testing personnel.

Membrane Materials

Mixed Cellulose Ester/Cellulose Acetate/Cellulose Nitrate/Polyethersulfone

Diameter (mm) 25/47/50/90

Pore Size (μm) 0.22/0.45/0.65/0.80/1.0/1.2/5/8

Color: White membrane with black grid/Black membrane with white grid

Wettability: Hydrophilic

Features

Complies with ISO7704; optimal for microbial retention and growth, with a microbial recovery rate >90%;

Sterilizing filtration efficiency: LRV >7 (ATCC 19146 Brevundimonas diminuta, ASTM bacterial challenge test);

High flow rate; grid lines on the membrane facilitate colony identification and counting without affecting colony growth.

Application Fields

Used in the "membrane filtration method" for microbial testing of solid, liquid, and gas samples;

Pharmaceutical Industry: Used to detect the total number of aerobic bacteria, molds, and yeasts in pharmaceuticals and injections, as well as the microbial limits in purified water and water for injection, ensuring drug quality and safety.

Food and Beverage Industry: Detects microbial contamination in food and beverages, such as E. coli and Salmonella, to ensure hygienic quality and prevent food safety issues caused by excessive microorganisms.

Water Treatment Industry: Filters microorganisms in drinking water and industrial water, assesses sanitary indicators such as total coliforms, and provides a basis for water quality monitoring and treatment.

Other Fields: Also used for microbial enrichment culture after air or surface sampling, such as cleanroom environmental monitoring; as well as in research areas like microbial isolation and antibacterial efficacy testing.