Optimization and validation of analytical methodologies for the determination of priority pollutants in vegetable samples

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a large class of organic compounds widespread in the environment and are generated mainly by incomplete combustion of fossil fuels or by pyrolysis in industrial processes. According to IARC, some of these compounds have been catalogued as carcinogenic (Group 1), probably carcinogenic (Group 2A), possibly carcinogenic (Group 2B) and not classifiable as to carcinogenicity (Group 3) to humans, who are exposed to these compounds by inhalation of contaminated air or via dietary intake. Nowadays, there is no analytical methodology that guarantees the extraction and the detection of PAHs at a trace level in horticultural crops. For this reason, this project attempts the optimization of an analytical procedure in different vegetable matrices (lettuce, tomatoes, cauliflowers) using the ultrasound assisted extraction technique, followed by a clean-up step employing adsorption chromatography with alumina as a stationary phase and its detection with gas chromatography coupled to a tandem mass spectrometry (GC – MS/MS). With this analytical procedure developed, the limits of detection (LODs) were calculated for each vegetable as 432 ng/g - 16000 ng/g (lettuce in fresh weight), 439 ng/g - 16257 ng/g (tomato in fresh weight) and 456 ng/g - 16257 ng/g (cauliflower in fresh weight) but the recoveries and precision were poor for all the matrices evaluated (0.8% - 37.3% and 83.6%, respectively) stressing the complexity