• Glossary


    Active Environmental Monitoring

    Method by which a known volume of air is sampled to allow quantifiable results to be calculated

    Barrier Pack

    Redipor® Barrier Pack products are packed using a gas impermeable layer to prevent the ingress of decontamination gases such as VHP whilst still allowing easy examination of the contents before use.

    Colony Forming Units (CFU)

    An estimate of the number of viable cells in a sample. Accuracy is limited because only those cells that grow into a discrete visible colony can be counted. Therefore conditions must be controlled to enable comparison.

    Contact Plates

    65mm diameter agar plate with a raised meniscus of agar to allow contact with a surface. Mainly used for surface sampling within an environmental monitoring program, but also used in active air samplers, such as the SAS. Also known as RODAC (Replicate Organism Detection and Counting) plates.

    European Pharmacopeia (EP or Ph Eur)

    The European Pharmacopoeia is a single reference work for the quality control of medicines in the signatory states of the European Convention. The official standards published within provide a legal and scientific basis for quality control during the development, production and marketing processes.

    Good Manufacturing Practice (GMP)

    A system for ensuring that products are consistently produced and controlled according to quality standards. It is designed to minimize the risks involved in any pharmaceutical production that cannot be eliminated through testing the final product.

    Growth Promotion Testing

    A quality control test to determine the viability of a batch of culture media which involves inoculating the pre-poured plates with control organisms and comparing their performance against a reference.

    Harmonised Media

    A group of media types that comply with harmonisation between the USP, EP and JP (Japanese Pharmacopeia) for the microbiological examination of non-sterile products.


    A barrier device that provides both a physical and aerodynamic barrier between a clean room and a work process, typically as a sealed cabinet with externally accessed glove ports.

    Irradiated Media

    Standard pre-poured plates and bottles which once packed pass through an additional sterilisation process where they are exposed to gamma (ɤ) irradiation, typically at a dose between 5 and 35 kGy.

    Medicines and Healthcare products Regulatory Agency (MHRA)

    An executive agency of the Department of Health responsible for regulating medicines and medical devices in the UK.

    Most probable number (MPN)

    Otherwise known as the method of Poisson zeroes, is a method of getting quantitative data on concentrations of discrete items from positive/negative (incidence) data. There are many discrete entities that are easily detected but difficult to count – Wikipedia. Commonly applied to estimate contamination in water samples. Within the SAS it is a statistical correction to account for duplication at each impaction point.

    Neutraliser 4

    Cherwell’s own terminology for a composition of 4 neutralising agents (0.07% Lecithin, 0.5% Tween 80, 0.05% Sodium thiosulfate, 0.1% L-histidine) to neutralize residual disinfectants/preservatives – Chlorhexidine, Hexachlorophene, mercural (& organo) compounds, Quaternary ammonium compounds, Amphoterics, Aldehydes & phenolic compounds & Halogen compounds. Similar to Countact and Protect agar plates from other suppliers.

    Non Viable Monitoring

    A method of monitoring and typically counting the number of particles within a volume of air, also referred to as particle counting.

    Passive Environmental Monitoring

    Method by which an unknown quantity of air is sampled so results can only be expressed as time exposed. Methods include settle or exposure plates.


    Redipor is the brand name used by Cherwell Laboratories for the range of prepared microbiological media.

    Replicate Organism Detection and Counting Plates (RODAC Plates)

    Also known as Contact plates, see above

    Restricted Access Barrier Systems (RABS)

    A barrier device that provides both a physical and aerodynamic barrier between a clean room and a work process.

    Settle Plates

    A passive air sampling method whereby a Petri dish is exposed for a pre-determined amount of time, typically 4 hours.

    Single Stage Sieve Sampling

    An active air sampling method where air is drawn through a perforated sampling head to impact airborne particles onto a capture medium below, such as an agar plate. Examples include the SAS air sampler.

    United States Pharmacopeia (USP)

    Scientific standards for the identity, strength, quality, and purity of medicines, food ingredients, and dietary supplements manufactured, distributed and consumed worldwide and enforceable in the United States by the Food and Drug Administration (FDA).

    Vaporised Hydrogen Peroxide (VHP)

    Also known as hydrogen peroxide vapour, HPV. A low-temperature antimicrobial vapour used to decontaminate enclosed and sealed areas such as laboratory workstations and isolation and pass-through rooms.

    Viable Monitoring

    A method of monitoring that captures and propagates viable particles, such as active air sampling.

    Contact Cherwell Laboratories

  • News

  • Events