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Common factors affecting limulus test results


Bacterial endotoxin test for drugs is a new technique with simple operation, high speed, high standardization and low cost. It is also an in vitro test method with complex biological reactions. Because of many factors, the accuracy of experimental operation is particularly important. Secondly, there are more than 680 kinds of drugs in American Pharmacopoeia, but the endotoxin limits of the tested products are different in China due to the difference of body weight between China and foreign countries. Therefore, in practice, the types and methods of literature reports contained in the American Pharmacopoeia can only be used as a reference, and the inspection law of the same drug can not be copied in order to avoid errors in the work. Therefore, we should pay attention to the following problems in practical work:

1. The sensitivity and self-agglutination time of the compound limulus reagent product should be added before the experiment, because the change of the sensitivity or the quality of the limulus reagent itself does not meet the requirements can affect your experimental results.

2. Value error or instability of bacterial endotoxin can affect the experimental results. It is recommended that you select the standard bacterial endotoxin provided by the mid-test and calibrate the titer of the standard bacterial endotoxin if necessary or if conditions permit.

3. Please choose the water for bacterial endotoxin test provided by the manufacturer. Because: BET water is a special kind of water. It not only requires the limit of bacterial endotoxin < 0.03EU/ml, but also requires a strict PH (6.0-8.0) range. It can not be replaced by water for injection.

4. Error of experiment operation: operation sequence and proficiency are particularly important. The experimental sequence is as follows:

(1) Preparation of endotoxin standard solution dilution test product lysis limulus reagent placement of test tube addition of sample or reagent sealing constant temperature observation results and records

5. Effect of cleanliness of experimental instruments: generally soak in sulfuric acid cleaning solution for 4 hours, rinse with tap water, then rinse three channels with fresh distilled water, and keep dry heat (250 C) for 1.5 h. The glassware used in the experiment must be strictly aseptic and pyrogen free. It is suggested that disposable plastic products should not be used.

6. Experimental conditions: The laboratory requires clean, dust-free air circulation. If the air-conditioning room is equipped with an ultra-clean worktable.

7. Temperature: The laboratory temperature is 25 (+2). The temperature of the constant temperature water bath is 37 (+1). It is suitable for the laboratory.

8. The sample itself interferes with the use of specific tachypleus amebocyte lysate or common tachypleus amebocyte lysate plus factor G inhibitor for polysaccharide-containing drugs. The PH value should be adjusted for samples with lower pH value.