Method validation and occurrence of dioxins and furans (PCDD/Fs) in fish from Brazil

Abstract

An isotope dilution method for quantification of 17 polychlorinated dioxins (PCDDs) and furans (PCDFs) in fish is described. The method uses pressurized liquid extraction (PLE) followed by clean up steps (elution of extracts into two sequential columns filled with distinct stationary phases: acid silica-gel and Florisil®) and gas chromatography coupled with high resolution mass spectrometry (GC-HRMS) analysis. ¹³C₁₂-labelled PCDD/Fs were used as internal and injection standards. The method was validated in accordance with specific requirements defined by the European Commission as described in the regulations 2012/252/EU and 2011/1259/EU. The EPA 1613 method was also used as the reference. Precision and recovery were evaluated at three levels for each PCDD/PCDF by means of spiked samples. Trueness was checked by analysis of a certified reference material (CRM). The following figures of merit were also assessed: linearity, selectivity, limit of detection (LOD), limit of quantification (LOQ) and measured uncertainty. Consistent results within the guidelines established were achieved for all of the parameters evaluated. Finally, 132 samples of 25 different species of fish were collected from different regions of Brazil over a 13 months period. No sample presented concentration higher than the maximum permitted level. The following dioxins and furans were found in some of these samples: 2,3,7,8-TCDF (19 samples), OCDD (2 samples) and 2,3,4,7,8-PeCDF, 1,2,3,7,8 PeCDD, 1,2,3,4,6,7,8-HpCDF (1 sample each) at levels higher than their LOQs. This validated analytical method has been used by the Ministry of Agriculture, Livestock and Food Supply of Brazil.