APPLICATION OF QUANTITATIVE ASSAY FOR END OTOXIN USING IMMOBILIZED HISTIDINE AND FILTRATION PLATE TO PARENTERAL DRUGS

We improved the Limulus amebocyte lysate (LAL) rest for endotoxins in parenteral drugs using immobilized histidine and a filtration plate. I n order to deal with many samples at the same time and to apply to a r outine assay, we used a filtration plate having 96 wells instead of a filter unit with a working volume of 2 ml. LAL test-affecting substanc es which are contained in a parenteral drug were separated from endoto xins by adsorbing endotoxins on immobilized histidine in the well of a filtration plate. Then the adsorbed endotoxins were allowed to react with LAL, reagent in the same well. We defined that this method had th e higher precision than conventional methods and was not influenced by the concentrations of endotoxin and parenteral drugs. Hence we examin ed the recovery of endotoxin spiked to 23 kinds of parenteral drugs by this method, as a result, 100+/-25% of recovery was obtained from 17 kinds of them.