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What is Laser Induced Fluorescence (LIF)? – PMT (GB) Ltd.

What is Laser Induced Fluorescence (LIF)?

Posted by Ian Norman on

What is Laser Induced Fluorescence (LIF)?

Laser Induced Fluorescence, or LIF, is a real time microbial method similar to optical particle counting wherein particles are measured independently using laser light in order to assess each particle’s specific make up and to determine whether or not the particle is a microorganism. Due to their increased number of fluorescent molecules, microorganisms can be easily identified through the use of Laser Induced Fluorescence and, more specifically, by an evident intensity of fluorescent light as well as higher wavelengths.

What are the benefits of Laser Induced Fluorescence (LIF)?

There are a number of benefits for using Laser Induced Fluorescence compared to the more traditional rapid and growth-based methods of real time microbial monitoring.


Laser Induced Fluorescence does not require any media or consumables; making it cheap to run and easy to maintain.

Instant real time results

A real time microbial method based on Laser Induced Fluorescence also provides instant feedback and allows early decisions about the environment being monitored.

Discrimination between microbial and interferent particles

By employing factory set algorithms and two photo-multiplier tubes (PMT’s), discrimination between microbial particles and interferent particles is possible.

Continuous monitoring

If the LIF instrument has an in-built compliant (to ISO21501-4) particle counter, like BioTrak, it can be included in an FMS instead of an OPC and microbial and particulate data can be continuously monitored, with alarm notifications being received for out of compliance data, as it happens.

Capture and grow bioburden

Bioburden can be captured onto a gelatine membrane and, if viable, can grow on TSA.

Remote sampling

LIF can also be used with a battery pack (UPS) for remote sampling activities.

To find out more about our Real Time Microbial Monitoring and Microbial Air Sampler products and services get in contact today by emailing us at or, alternatively, you can call us on +44 (0) 1684 312 950

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