Original scientific paper
PREPARATION OF WATER-RESISTANT SUBSTANCES FOR ECOTOXICOLOGICAL TESTING
J. Vržina
; Zavod za javno zdravstvo grada Zagreba, Zagreb, Hrvatska
L. Ulm
; Zavod za javno zdravstvo grada Zagreba, Zagreb, Hrvatska
V. Schiesl
; Zavod za javno zdravstvo grada Zagreba, Zagreb, Hrvatska
M. Šateva
; Ivasim, Ivanić Grad, Hrvatska
Abstract
Abstract
Test methods for assessment toxicity chemical substances to aquatic organisms have been described by various organizations including the OECD, EU or ISO. Those test methods are typically designed for substances with precise generic description and substances, which are readily water soluble, chemically stable and non-volatile. When test methods are applied to substances with different chemical properties (sparingly soluble, unstable or volatile substances or those of a complex composition) it is possible to expect some difficulties in toxicity evaluation.
According to present knowledge the best test method for toxicity examination of water-resistant substances is WAF methodology (Water Accommodated Fraction). WAF is an aqueous medium containing only that fraction of a substance which remains in the aqueous phase after mixing and phase separation.
The subjects for our examination were water-resistant greases (some of them have very strong adhesive characteristics) and lubricant oils which form emulsion with water. According to their chemical composition there are synthetic based esters and plant oils thickned with soaps and organophylic bentonits. The greases were mixed with deionised water and mineral media on magnetic stirrer and during the time period of 24-96 hours some parameters were defined (concentration of lipophylic substances, total organic carbon and organic acids eventually made by ester hydrolyzis).
Keywords
sampling by water accomodated fraction (WAF) of sparingly soluble substances; toxicity determination of sparingly soluble water constituents; toxicity properties of lubricating greases
Hrčak ID:
10654
URI
Publication date:
30.6.2000.
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