Weber-Frick C, Schmidt-Lorenz W
Laboratorium für Lebensmittel-Mikrobiologie, Institut für Lebensmittelwissenschaft Eidgenössische Technische Hochschule, Zürich.
Zentralbl Bakteriol Mikrobiol Hyg B Umwelthyg Krankenhaushyg Arbeitshyg Prav Med. 1988 Jan;185(4-5):430-51.
Comparative examinations with three different micro-models for the LAL-test methods,--namely the capillary test, Endotoxin-test "Mini" and Coatest-Endotoxin-method-, tested with 11 Enterobacteriaceae- and 6 Pseudomonas-type-strains and isolates from foods gave only slight differences for the endotoxin content. Out of 250 single measurements per test method the capillary test as well as the Coatest-Endotoxin-method gave count limits between 2.8 X 10(1) and 7.4 X 10(3) CFU/ml. For the endotoxin-test method "Mini" the limits were one log unit higher-namely between 8.6 X 10(2) and 5.0 X 10(4) CFU/ml. The maximum values for count limits of all three methods correspond to approximately 1 ng Endotoxin. For the two gel test methods a relative error of +/- 15% has to be taken into account; for the chromogen method however, the relative error lies within +/- 25%, if the concentration is 0.0125 ng LPS/ml or lower. Between 0.025 and 0.1 ng LPS/ml or 0.075 and 0.1 ng LPS/ml the relative error is reduced to +/- 16% and +/- 5% respectively. The study has shown that the three micro tests in question as tested with pure cultures give comparable and reproducible results; inspite of the high relative error.
