PT  - JOURNAL ARTICLE
AU  - Steindler, Kathy A.
AU  - Tsuji, Kiyoshi
AU  - Enzinger, R. Michael
TI  - Potentiating Effect of Calcium Gluconate on the Limulus Amebocyte Lysate (LAL) Gelation-Endpoint Assay for Endotoxin
DP  - 1981 Sep 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 242--247
VI  - 35
IP  - 5
4099  - http://journal.pda.org/content/35/5/242.short
4100  - http://journal.pda.org/content/35/5/242.full
SO  - PDA J Pharm Sci Technol1981 Sep 01; 35
AB  - Falsely high levels of endotoxin in calcium gluconate solutions were detected by use of commercially available Limulus amebocyte lysate (LAL) reagents. The endotoxin levels detected did not correlate with the data of the United States Pharmacopeial pyrogen test. The ionic form of calcium in calcium gluconate was responsible for enhancing this LAL sensitivity. The LAL method quantitated significantly higher levels of endotoxin than those of the USP pyrogen test. The positive bias was eliminated by testing with the LAL reagent when its sensitivity was maximized by reconstituting the LAL with an approximately 50 mM magnesium solution. The endotoxin levels thus detected by the LAL correlated well with the data of the USP pyrogen test. Prior to the acceptance of a LAL method, the method should be validated by spiking the testing material, free of endotoxin, with a known amount of endotoxin to assure that interference from the testing material is minimal. Any alterations in the composition of the LAL reagent may affect the degree of interference.