Bacterial Endotoxin Testing Method

Bacterial endotoxin is a biological toxin produced by Gram-negative bacteria that can trigger inflammatory responses in humans. It can be measured via routine blood tests, and the specific detection method is as follows:

1. Sterilize all required laboratory glassware using a dry-heat oven, then dissolve the limulus amebocyte lysate (LAL) reagent in water and prepare it for use.

2. Add the test sample to a tube containing the prepared LAL reagent (test tube); add endotoxin standard to another tube as the positive control; and add only the LAL reagent solution to a third tube as the negative control.

3. Gently mix the contents of each tube, seal the tube openings, and incubate the tubes vertically in a water bath maintained at 36–38°C for 58–62 minutes.

4. Carefully remove the tubes from the water bath and slowly invert them. A positive result is indicated if the gel formed remains intact and does not detach from the tube wall; a negative result is indicated if the gel fails to maintain integrity and slides off the tube wall.

5. If both the test tube and the positive control tube yield positive results, the test must be repeated.