Contamination of polychlorinated biphenyls in honey from the Brazilian state of Rio Grande do Sul.

Persistent organic pollutants are characterised by their chemical structure, environmental persistence and toxicity to human and wildlife populations. The production of these chemicals is regulated and restricted. However, they continue to be detected in the environment. In this study, the occurrence of 11 congeners of polychlorinated biphenyls (PCBs 28, 52, 77, 81, 101, 118, 126, 138, 153, 169, and 180) was investigated in 90 honey samples produced in the Brazilian state of Rio Grande do Sul. The samples were from different municipalities, production systems and floral origins. Extraction was performed using the modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged and Safe) followed by gas chromatography with micro-electron capture detector. The results showed the presence of four congeners (PCBs 28, 77, 81, 101) in 15 honey samples confirming the environmental contamination in Southern Brazil. Among the contaminated samples, no significant differences were identified regarding the production system and floral origin.

Pesticide residues determination in common bean using an optimized QuEChERS approach followed by solvent exchange and GC-MS/MS analysis.

BACKGROUND: Common bean is a staple food in Latin America and Africa; however, studies about contamination of common bean with pesticides are rarely reported. So, the goals of this study were to validate a multiresidue method and apply it in monitoring of pesticides in common beans. Extraction was performed applying the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach to ground samples. Octadecylsilane and primary-secondary amine were used for clean-up, and a solvent exchange step was performed before injection for gas chromatography-tandem mass spectrometry analysis. Method validation was done analyzing blank samples spiked at 20, 30, 50, and 100 µg kg-1 (n = 5). Linearity and linear range were assessed by the analysis of standard solutions at concentrations of 5, 15, 25, 50, 75, 100, and 150 µg L-1 . RESULTS: The method was successfully validated for 91 (64.1%) of the 142 compounds studied (139 pesticides and three degradation products). Limits of quantification were equal to 20 µg kg-1 , 30 µg kg-1 , 50 µg kg-1 , and 100 µg kg-1 for 18 (12.7%), 17 (12.0%), 21 (14.8%) and 35 (24.6%) compounds respectively. Fifteen (10.6%) compounds were not detected at any level, and 36 (25.4%) did not fulfill the requirements for a quantitative method. Sixteen common bean samples of South of Brazil were analyzed. Two samples were positive: one for tebuconzole and a second for picoxystrobin, permethrin, and cyproconazole. Cyproconazole is not allowed for use in the common bean crop, its use being a violation. CONCLUSION: As demonstrated, the validated approach is suitable for pesticide residues determination in common bean. Results of the sample analysis show that the control of pesticide residues in common bean is necessary to ensure food safety. © 2020 Society of Chemical Industry.