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Appl. Environ. Microbiol., 05 1995, 1763-1769, Vol 61, No. 5
J Douwes, P Versloot, A Hollander, D Heederik and G Doekes
The influence of various filter types and extraction conditions on the
quantitation of airborne endotoxin with the Limulus amebocyte lysate test
was studied by using airborne dusts sampled in a potato processing plant.
Samples were collected with an apparatus designed to provide parallel
samples. Data from the parallel-sampling experiment were statistically
evaluated by using analysis of variance. In addition, the influence of
storage conditions on the detectable endotoxin concentration was
investigated by using commercially available lipopolysaccharides (LPS) and
endotoxin-containing house dust extracts. The endotoxin extraction
efficiency of 0.05% Tween 20 in pyrogen-free water was seven times higher
than that of pyrogen-free water only. Two- times-greater amounts of
endotoxin were extracted from glass fiber, Teflon, and polycarbonate
filters than from cellulose ester filters. The temperature and shaking
intensity during extraction were not related to the extraction efficiency.
Repeated freeze (-20 degrees C)- and-thaw cycles with commercial LPS
reconstituted in pyrogen-free water had a dramatic effect on the detectable
endotoxin level. A 25% loss in endotoxin activity per freeze-thaw cycle was
observed. Storage of LPS samples for a period of 1 year at 7 degrees C had
no effect on the endotoxin level. House dust extracts showed a decrease of
about 20% in the endotoxin level after they had been frozen and thawed for
a second time. The use of different container materials (borosilicate
glass, "soft" glass, and polypropylene) did not result in different
endotoxin levels. This study indicates that the assessment of endotoxin
exposure may differ considerably between groups when different sampling,
extraction, and storage procedures are employed.
Copyright © 1995, American Society for Microbiology
Influence of various dust sampling and extraction methods on the measurement of airborne endotoxin
Department of Epidemiology and Public Health, Agricultural University Wageningen, The Netherlands.
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