Bacterial Endotoxin Test - LAL test

The bacterial endotoxin test or LAL test is performed to detect the presence of bacterial endotoxins in injectable pharmaceutical products, biological products, medical devices, dialysis waters, and other products administered intrathecally.

The bacterial endotoxin test is carried out with:

Reagents and endotoxins for LAL test, traditional or recombinant
Apyrogenic-certified consumables for LAL test, including water, glassware, and plastics
Instrumentation for LAL test

Reagent LAL traditional

The name of the test comes from the Limulus Amebocyte Lysate (LAL), an extract obtained from the amebocytes of Limulus polyphemus. The lysate has the characteristic of reacting with endotoxins present in the membranes of Gram-negative bacteria (lipopolysaccharides), triggering an enzymatic cascade that leads to coagulation. It is precisely this property that is exploited to perform the LAL test.

The LAL test can be performed using qualitative or quantitative methods.

Recombinant reagent

The recombinant LAL reagent version represents a sustainable and innovative future for the bacterial endotoxin test.

It provides the same reliable results as the conventional LAL reagent without containing animal-derived components, utilizing the same enzymatic cascade and avoiding cross-reactivity with 1,3-β-D-glucans.

The recombinant test can be performed using a quantitative method.

Apyrogenic consumables for LAL test

The bacterial endotoxin test must be performed with glassware, plastics, water, and, in general, consumables certified as apyrogenic and free from interferents. Successful testing requires accuracy and care to avoid contamination from unsuitable materials.

Instrumentation for LAL test

It is necessary to have a few dedicated instruments, preferably used only for the LAL test:

vortex
micropipettes and automatic dispenser
digital thermometer
for the gel-clot method, a dry incubator is required
for kinetic methods, an optical reader incubator is required

Reagents and endotoxins for LAL test

Pyrogen-free LAL test consumables

LAL test dedicated instruments

The LAL test requires thorough training and the implementation of procedures that include operator qualification, reagent lot validation, characterization of the products under analysis, and definition of the routine test.

The bacterial endotoxin test can be performed using qualitative or quantitative methods.

Test Methods

Gel-clot

This is the reference method for most laboratories.

It is a qualitative or semi-quantitative method based on the formation of a solid gel.

Regulated by Methods A and B, EP (European Pharmacopoeia).

Uses the traditional LAL reagent (maximum sensitivity 0.03 EU/ml).

Kinetic Turbidimetric

Endotoxin quantification is related to the development of turbidity (maximum sensitivity 0.001 EU/ml).

Regulated by Methods C and F, EP (European Pharmacopoeia).

Uses the traditional LAL reagent.

Kinetic Chromogenic

Endotoxin quantification is related to the development of color (maximum sensitivity 0.001 EU/ml).

Regulated by Methods D and E, EP (European Pharmacopoeia).

Uses traditional or recombinant LAL reagent.

Types of Test

Product Characterization

Usually performed on pharmaceutical products, this is an in-depth study that determines the dilution at which the sample will be tested routinely. Pharmaceutical products often have particular characteristics that can interfere with the reaction if tested as-is. A series of product dilutions is analyzed to find the most suitable one for performing the test and obtaining an accurate, reproducible, and reliable result.

Validation (USP/EP interference test)

This is performed to demonstrate that the product does not interfere with the LAL test. This test is conducted at a dilution equal to or lower than the maximum valid dilution (MVD) for that product. The MVD is determined by the endotoxin limit for the product. Validation is required for all finished parenteral or intrathecal products. The test method must be validated using three lots of the finished product before the release test is used for product release. The procedure is also used to demonstrate that the test is valid when used to test raw materials or in-process materials.

Release Testing

Routine testing used to release products. The test is performed using the same dilution validated during the validation phase.

LAL TEST: RECOMBINANT METHOD Technical Summary n. 2

Posted in: Technical guides

July 30th 2025

The new recombinant bacterial endotoxin test with PyroSmartNextGen® reagent, produced by Associates of Cape Cod (ACC). Further information on the method and a section dedicated to all the products available in the catalog and required
Read more
LAL TEST: GEL CLOT METHOD Technical Summary n. 1

Posted in: Technical guides

July 10th 2025

A brief introduction to the LAL test and, in detail, an in-depth look at the Gel Clot method on water with a section dedicated to all the products available in the catalogue and necessary to correctly perform these operations
Read more