The Open Environmental Pollution & Toxicology Journal

2010, 2 : 1-7
Published online 2010 March 02. DOI: 10.2174/1876397901002010001
Publisher ID: TOEPTJ-2-1

Turbidity and Color Correction in the Microtox Bioassay

John Ashworth , Erik Nijenhuis , Bozena Glowacka , Lang Tran and Lisa Schenk-Watt1
ALS Laboratory Services, 9936-67, Ave., Edmonton AB, Canada;

ABSTRACT

We propose a new method of correcting for the effects of color and turbidity on bacterial light output measurements in the Microtox™ bioassay. Using our method, toxicity assessment involves clearly defined calculation factors, based on light loss measurements using a modified double-cuvette.

An existing color-correction method requires additional spectrometer measurements and over-corrects for turbidity. For a range of clear, colored fluids our new method and the existing method gave similar, corrected EC50 values.

Our new method needs no separate equipment and is likely to provide valid toxicity assessments of whole fluids, without any need for sample clarification. It accounted for > 90 % of the variance in loss of measured bacterial light caused by color and turbidity of a range of test fluids.

Keywords:

Turbidity, Color, trace element, Microtox, Bioassay.