Microbics Corporation

Azur Environmental

Charles Walbourn

Malbone W Greene

Don Isenberg

Ker-Kong Tung

Grace Scheibner

A method for the direct determination of the toxicity of a solid material by direct contact between the solid sample and a luminescent microorganism, consisting of the steps of forming a suspension of a luminescent microorganism in a 0.5% to 6% solution of NaCl or 20% solution of sucrose in distilled water diluent and contacting a sample of the solid to be tested directly with the suspension of luminescent microorganisms. A control including the microorganism in the diluent is also prepared. The combination of microorganism suspension and solid sample is incubated for a sufficient time to allow for the toxicity of the sample to affect the metabolism of the living organism. During or subsequent to the incubation period the combined organism and sample are subjected to a separation step to separate a major portion of the particulate solid from the suspension of microorganisms. The light output of the separated suspension is determined and compared with the light output of the control to arrive at the change in light output of the microorganism due to contact with the solid sample.

Method for the direct determination of the toxicity of particulate solids

A method of obtaining small representative solid-phase samples from a large solid-phase sample. Solid-phase material is optionally separated from any liquid-phase that may be present and is mixed. A portion of the mixed solid-phase particulate sample is selected which provides an intermediate size representative sample. After adding liquid diluent to the intermediate particulate sample in a vessel, the suspension is agitated to promote separation of small particles as may be adhering to large particles to obtain a homogeneous suspension. Agitating is preferably carried out using a magnetic stirring bar. Fractions of this homogeneous suspension are then obtained by aspirating using a pipette and transferred to test tubes which will constitute small, truly representative solid-phase particulate samples from which replicate testing can be confidently performed.

Method of obtaining small representative solid-phase samples

A method for compensating toxicity test data for the measured toxicity of a reference sample by the steps of: a. obtaining toxic response data for a plurality of concentrations of at least two different test samples, including reagent controls having zero sample concentration for each sample; b. defining the sample having the smallest toxic response at high concentrations as the reference sample; c. computing the toxic response of the test sample relative to that for the reference sample for at least two concentrations in accordance with the equation:

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Encinitas, CA, United States of America

Charles Walbourn