Journal
ANALYTICAL METHODS
Volume 6, Issue 18, Pages 7367-7373Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c4ay00789a
Keywords
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Funding
- Brazilian agencies CAPES
- CNPq
- FAPESP [2011/23498-9]
- Nucleo de Pesquisa em Tecnologia e Inovacao para Sustentabilidade da Agricultura (NAPTISA)
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [11/23498-9] Funding Source: FAPESP
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A multi-pumping flow system was developed for automation of the acute toxicity bioassay using the Vibrio fischeri bacteria. Solenoid micro-pumps were exploited to improve mixing conditions, and to accomplish the required in-line dilutions of the tested compounds by modifying the sample volume and exploiting the partial overlap between the sample zone and the bacterial suspension. A spiral flow cell, placed at the emission window of a spectrofluorimeter, was used for signal measurements and a lab-made water bath based on the Peltier effect was used for temperature control of the bioassay. A 120 mu L of the bacterial suspension was selected in order to minimize its consumption and, consequently, the costs of the assay. The contact time between the bacterial suspension and sample was reduced to 5 min to increase the sampling throughput and to avoid luminescence fading due to the short bacteria lifetime. The coefficients of variation were estimated at 2.4 and 2.0% (n = 10), in the absence and in the presence of 0.60 mg L-1 Zn(II), respectively. The EC50 values for emerging contaminants (parabens, caffeine, acetaminophen, diclofenac, and salicylic acid) agreed at the 95% confidence level with those obtained with the commercial BioTox (TM) kit performed in a microplate. The proposed flow system is then a simple, fast, robust, and accurate alternative for acute toxicity determination, using low sample and bacterial suspension volumes. Furthermore, it presented other advantages in relation to batch and previously proposed flow-based bioassays, such as in-line osmotic adjustment and sample dilutions, and the evaluation of toxicity kinetics for every assayed sample.
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