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Selection of solvent for polycyclic aromatic hydrocarbons
microwave-assisted extraction from fish
M. Machado 1,2 , M. J. Ramalhosa 1,2 , P. Paíga 1 , S. Morais 1 , C. Delerue-Matos 1 and M. B.
P.P. Oliveira 2
1 Requimte, Instituto Superior de Engenharia do Porto, Rua Dr. António Bernardino de Almeida 431,
4200-072 Porto, Portugal.
2 Requimte, Serviço de Bromatologia, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal
Cunha 164, 4099-030 Porto, Portugal.
In contrast to the potential health benefits of dietary fish intake, an issue of concern related
with frequent fish consumption is the risk derived from exposure to chemical pollutants.
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds with two or
more fused aromatic rings. According to different health and environmental protection
organizations, such as the International Agency for Research on Cancer (IARC) and the United
States Environmental Protection Agency (USEPA), several PAHs have mutagenic,
carcinogenic and endocrine disrupting properties [1]. In particular, benzo[a]pyrene has been
identified as being highly carcinogenic. The USEPA has promulgated 16 unsubstituted PAHs
as priority pollutants which are commonly quantified for purposes of evaluating potential
health effects in humans.
In this study, preliminary tests were made to choose the solvent for microwave-assisted
extraction of 18 PAHs (the 16 regarded as priority pollutants by the U.S. Environmental
Protection Agency, benzo[j]fluoranthene and dibenzo(a,l)pyrene) from fish samples. From the
principles of microwave heating, it is understood that the choice of the microwave extraction
solvent, is a very important parameter, and depends upon its ability to absorb microwaves as
defined by its dielectric constant. Non-polar solvents cannot absorb microwave energy and
despite the fact that they are known to be good extraction solvents for aromatic compounds
they cannot be used alone. Acetonitrile and hexane-acetone (1:1, v/v) were tested. Studies were
performed at five extraction temperatures (90, 100, 110, 120 and 130 ºC), with the following
extraction conditions: 0,5 g of fish sample, 20 mL of solvent, 20 minutes of extraction time,
100 psi, 100% of power and medium stirring. For both solvents, the best results were obtained
at 110 ºC and 120 ºC. For acetonitrile, the overall average recoveries for the 18 PAHs were
76.9±17.9% and 74.9±17.4% at 110 ºC and 120 ºC, respectively. For hexane-acetone (1:1, v/v),
mean recoveries values ranged between 66.2±18.2% (at 110 ºC) and 67.5±19.8% (at 120 ºC).
Acetonitrile at 110 ºC was selected as the optimum.
Acknowledgments:
M. Machado thanks the FCT for her BII fellowship.
References:
[1] USEPA (2000), Guidance for Assessing Chemical Contaminant Data for Use in Fish Advisories,
EPA/823/B-00/007, United States Environmental Protection Agency.
328 3 rd meeting of young researchers at UP