LAL Testing – Bacterial Endotoxin Testing

The LAL (limulus amebocyte lysate) testing, also known as bacterial endotoxin testing, is an in vitro assay used to detect the presence and concentration of bacterial endotoxins in drugs and biological products, and is an important part of pharmaceutical microbiology. Endotoxins, which are a type of pyrogen, are lipopolysaccharides present in the cell walls of gram-negative bacteria. Pyrogens as a class are fever-inducing substances that can be harmful or even fatal if administered to humans above certain concentrations.

The LAL bacterial endotoxin testing team at Pacific BioLabs performs the Kinetic Chromogenic LAL bacterial endotoxin assay, a sensitive colorimetric assay that can detect bacterial endotoxin levels in solutions at concentrations as low as 0.005EU/mL.

In addition to pharmaceutical preparations, water can also be a source of pyrogens. Therefore, it may be important to perform endotoxin testing to routinely monitor water systems.

Bacterial Endotoxin Test Procedure

The reason the bacterial endotoxin test is also called LAL or limulus amebocyte lysate testing is because the lysate from blood cells (amebocytes) from horseshoe crabs (the latin name is limulus Polyphemus).  The lysate from the horseshoe crabs blood cells react with bacterial endotoxins.

Samples are mixed with the LAL reagent in a 96 well plate and a plate reader measure the color change over time.  The liquid in the wells becomes more yellow over time and the rate of that color change is proportional to the amount of endotoxin present in the sample.

The impact of inhibitory compounds has less of an impact using the kinetic chromogenic method than other methods.  In addition, the kinetic chromogenic method is more sensitive than other LAL testing methods.

Rabbit Pyrogen Test

The Rabbit Pyrogen Test in an in vivo test to detect pyrogens qualitatively. Rabbits have a similar pyrogen tolerance to humans, so by observing a change in body temperature in rabbits it is possible to make a determination of the presence of pyrogens. This method can detect non-bacterial endotoxin pyrogens as well as bacterial endotoxins.

Available Endotoxin and Pyrogen Testing Services

  • Kinetic Chromogenic LAL Method (for bacterial endotoxins) – in vitro
    • (10mL sample size required for water; call PBL for containers if needed.)
  • USP / JP / EP / ISO (material mediated) Rabbit Pyrogens Test – in vivo

Read More About LAL Endotoxin and Rabbit Pyrogen Testing

 

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