Control standard endotoxin

The <85> BET first appeared in 1980 as an informational chapter in the USP XX. Significantly, the USP adopted the FDA E. coli 0113 endotoxin standard as its reference standard and assigned units of potency to it. It also included information about calibrating a control standard endotoxin (CSE) to the RSE. 

Positive product control is inhibitory control and consists of the specimen or dilutions of the specimen, per STM 063, to which standard endotoxin is added. 

If the positive product control or endotoxin standard does not show the endpoint concentration to be within plus or minus twofold dilutions from the label claim sensitivity of the LAL reagent or if any negative control shows a gel clot endpoint. 

Qualification of the laboratory. Qualification of the laboratory includes qualifying analysts initially by demonstrating their proficiency at preparing the necessary reagents, standards, and controls. Analyst qualification is necessary for each type of bacterial endotoxin analysis test prior to performance of any testing on actual samples. 

Positive controls pipette duplicate 0.1-ml aliquots of freshly prepared endotoxin standard solution, bracketing the labeled lysate sensitivity, into separate 10 X 75 mm pyrogen-free test tubes. 

We have also applied ELISA to several biological pesticides including the endotoxin of Bacillus thurineiensis kurstaki (Btk). In this application to a macromolecular analyte, we have used a double antibody sandwich ELISA for Btk to measure the amount of ELISA reactive material in formulations of the pesticide. Figure 7 shows the use of an ELISA standard curve of gel purified Btk endotoxin to measure the immunoreactive material in dilutions of two Btk formulations. It has been demonstrated that ELISA can serve as a quick quality control check for formulations of Bacillus thurineiensis lsraelensis (44). Such examples indicate that immunoassays will be increasingly important as biologicals and products of recombinant DNA research impact our field (M) ... 

The turbidimetric principle and automated microtiter plate reading apparatus are more commonly used in the kinetic rather than the end-point mode. Turbidity readings of each reaction mixture are taken at frequent intervals throughout an incubation period. The logarithm of the time (the onset time) taken to reach a specified level of turbidity is inversely proportional and linearly related to the logarithm of the concentration of endotoxin in the material under test. Standardization is necessary with each series of assays. This approach is only practical for routine application using microprocessor-controlled equipment. 

Purity Residual proteins, chromosomal bacteria DNA, RNA, and endotoxin must be below specified limits. Sterility must be controlled by standard microbiological assays. 

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