Abstract: 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.

Abstract: 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:relative gamma=.GAMMA..sub.R =(L.sub.SC /L.sub.SX)(L.sub.RX /L.sub.RC)-1, where L.sub.SC =light output of the test sample control (i.e. for X=0),L.sub.SX =light output of the test sample for concentration X,L.sub.RX =light output of the reference sample for concentration X,L.sub.RC =light output of the reference sample control (i.e. for X=0); andd. generating a dose-response curve of concentration versus relative .GAMMA.