A Chemical Method for Determining Endotoxins in Cotton Dust and Lint Without Extraction

Abstract

Endotoxins present on cotton and released during carding have been implicated as a cause of byssinosis, a lung dysfunction found in some textile mill workers. The endotoxin content of cotton lints and dusts is frequently determined by the Limulus amoebocyte lysate (LAL) test. Although this test is a very effective measure of endotoxin in drugs and parenteral solutions, it is subject to interferences and false positives from other components in a more complex matrix such as cotton dust. To obviate these problems, we are investigating the quantitation of endotoxins by determining the 3- hydroxymyristic acid content of the sample. This fatty acid is reported to be unique to the lipid A portion of lipopolysaccharides from gram-negative bacteria and has been reported as a marker for endotoxin by others. A major source of error in deter mining endotoxins in cotton lints and dusts appears to lie with the extraction procedures used to remove the endotoxin from the cellulosic matrix. This is true for both chemical and LAL assays. To eliminate this time-consuming and error-producing step, we are investigating the direct hydrolysis of the endotoxin while still on the cellulosic matrix. The amount of 3-hydroxymyristic acid is determined by HPLC of the phenacyl ester and related to endotoxin content using a calibration curve prepared from E. agglom erans, generally the predominant bacterial species on cotton fiber. Endotoxin values for direct hydrolysis are from 10 to 40 times greater than those obtained for aqueous or phenol-water extracts of the same lints or dusts, implying that endotoxin from both intact and lysed bacteria may be quantitated. Reproducibility is improved over that obtained for extracts of cotton lints and dusts.