 |
| LAL (Limulus Amoebocyte Lysate) Test |
LAL (Limulus Amoebocyte Lysate) Test
LAL test is an in vitro test used to detect and
measure bacterial endotoxins. It is a quality control test required by FDA for
all parenteral drugs in their final stages of formulation.
Reagents:
Amoebocyte Lysate from horse shoe crab, Limulus polyphemus.
Principle:
1. The test is based on blood clotting reaction of
horse shoe crab.
2. The LAL reagent is derived from blood cells
(amoebocytes) of a horse shoe crab.
3. The blood cells are separated from the serum using
centrifugation and are than placed in distilled water, which causes them to
swell up and burst or lyse.
4. This lysis of the cells releases chemicals called
lysate that is purified and freeze-dried.
5. To test a sample for endotoxin detection the sample
is mixed with lysate and water, if coagulation occurs endotoxins are present.
6. The rate of reaction depends upon concentration of
endotoxins, pH, temperature.
Procedure:
1. Equipments should be depyrogenated.
2. Equal volume of LAL reagent and test solution (0.1
ml) are mixed in a test tube.
3. Incubation at 37 ℃ for 1 hour.
4. Remove the tube, invert in one smooth motion (180
degree) and observe the result.
Methods used:
1. Gelclot method - gel formation.
2. Turbidimetric - the turbidity occurs.
3. Chromogenic method - the development of color after
cleavage of a synthetic peptide chromogen complex.
Application:
1. To diagnose urinary tract infections and spinal
meningitis.
2. To assess food spoilage, air and water quality.
3. To determine the ability of new drugs to neutralise
toxic effects.
4. Raw materials, solutions, biological products are
tested.
Limitations:
1. LAL test cannot discriminate between living and
dead bacteria.
2. Cannot differentiate species of bacterial
endotoxins.
The Daily Youth- tdy24.com Presents
"LAL (Limulus
Amoebocyte Lysate) Test"
Written By
Sadia Akhtar
Student of Department of Microbiology
Jagannath University.
Email- sadiabd810@yahoo.com
 Test){kind=link}
0 Comments