Der Leitfähigkeitstest — Ein Testsystem zur Ermittlung der membrantoxischen Eigenschaften von Substanzen

Abstract

Summary: A new biotest system is introduced which is specific in terms of the measured effect but not in terms of the applied organisms. The system is able to detect the effect of membrane-toxic compounds e.g. detergents, organic solvents, and radical formers. Released into the environment, these substances damage biological membranes and therefore cause ion leakage into a surrounding medium. Ion leakage is taken as a measure for membrane damage and is determined as an increase of the electrical conductivity in the medium (conductivity test). The results presented for the tensides benzalkonium chloride, LAS (linear alkylbenzenesulfonate), and APG (alkylpolyglycoside) demonstrate the capability of the conductivity test to distinguish between the differing toxicological potential of these membrane-toxic substances. In contrast to most of the conventional biotests, the endpoint of the conductivity test is independent of a specific organism. This independence is demonstrated by the results obtained with benzalkonium chloride treatment of Elodeu canudensis, Lemna minor, and Suhiniu nutans. The conductivity test represents a versatile, easy to handle biotest system for the assessment of ecotoxicological effects caused by membrane-toxic substances.

Specific Detection of Membrane-Toxic Substances with a Conductivity Assay

“…The setup of the conductivity assay and the culture of E. canadensis,¸emna minor, and Spirodela polyrrhiza were described in DuK rholt et al (1995), Eich et al (1997), andSteger-Hartmann et al (1995a,b). Ten leaves of Elodea (fresh weight: 49 mg$8 mg) were incubated in 40 mL of an aqueous benzalkonium chloride solution and the subsequent electrolyte loss was monitored over a period of at least 24 h. After measurement the leaves were frozen and subsequently thawed in order to determine total electrolyte content of the leaves.…”

“…The conductivity assay is per se species independent. Since most of the membrane-toxic compounds are released into water, investigations were restricted to aquatic organisms (DuK rholt et al, 1995, Eich et al, 1997Steger-Hartmann et al, 1995a,b).…”