The kinetic turbidimetric Limulus Amebocyte Lysate (LAL) test assay is a method for detecting and quantifying bacterial endotoxins. This assay relies on the formation of a gel-like clot during the reaction between endotoxin and the LAL reagent, which results in increased turbidity (cloudiness) that can be measured over time. Here's an overview of the process:
When bacterial endotoxin (lipopolysaccharide, LPS) reacts with the LAL reagent derived from the horseshoe crab's blood, a cascade of enzymatic reactions is triggered.
These reactions activate clotting proteins in the LAL reagent, leading to the formation of an insoluble gel-like clot.
The extent and rate of turbidity increase (cloudiness) are directly proportional to the endotoxin concentration in the sample.
Sample Preparation: The test sample is mixed with the LAL reagent under controlled conditions.
Reaction Monitoring: The reaction mixture is placed in an incubating spectrophotometer, which continuously measures turbidity (optical density) at a specific wavelength.
Data Collection: The spectrophotometer tracks changes in turbidity over time. The time required to reach a threshold level of turbidity is inversely related to the endotoxin concentration.
Quantification: A standard curve is created using known endotoxin concentrations. The endotoxin content in the test sample is calculated by comparing its reaction time to the standard curve.
Quantitative Measurement: Provides precise endotoxin concentrations by analyzing reaction kinetics.
High Sensitivity: Capable of detecting low levels of endotoxins.
Real-Time Monitoring: Continuous tracking of turbidity allows for accurate determination of reaction kinetics.
Pharmaceutical product testing to ensure endotoxin levels are within safe limits.
Quality control for medical devices and injectable solutions.
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