Endotoxin Detection by Semi-Quantitative Gel-Clot Method

Preparation of test solutions

Prepare test solutions at concentrations of MVD, 0.5 MVD, 0.25 MVD or any other appropriate dilutions relative to the dilution at which the test for interfering factors was completed. Additionally, prepare a similar series of test solutions spiked with 2λ of CSE each (PPC).

Method

Carry out the procedure on the test solutions in duplicate as described under Test for interfering factors.

Calculation and interpretation of results

To calculate the endotoxin concentration in the product, determine for the series of test solutions the lowest concentration or the highest dilution giving a positive (+) reaction. Multiply this dilution factor with A to obtain the endotoxin concentration of the product.

For instance, if MVD is equal to 8 and the positive reaction was obtained at 0.25 MVD and 1was equal to 0.125 EU/ml, the endotoxin concentration in the test solution will be 8 x 0.25 x 0.125 =0.25 EU/mI.

If none of the dilutions of the series gives a positive reaction, the endotoxin concentration will be less than the value obtained by multiplying the lowest dilution factor with A. If all the dilutions of the series give a positive reaction, the endotoxin concentration will be more than the value obtained by multiplying the highest dilution factor with A.

Calculate the endotoxin content of the product under examination from the endotoxin concentration. The product under examination meets the requirements of the test if the endotoxin content is less than the endotoxin limit stated in the individual monograph.
Related: Bacterial Endotoxin Test (BET or LAL Test) Validation