RESUMO
Per- and polyfluoroalkyl substances are synthetic environmental pollutants previously used for packaging applications as a grease, oil, and water-resistant coating. Exposure reported in previous studies highlighting potential concerns with public health. This study evaluated performance of coated paper packaging used for microwave popcorn, snacks, and sandwich bags for presence of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Current paper packaging materials: seven popcorn bags and three snack and sandwich bags were analysed for PFOA and PFOS and compared to concentrations in microwave popcorn bags between 2005 and 2018. Only two microwave popcorn bags had average PFOA content above the limit of quantitation of 5.11 ng g-1 paper. All other sample types had PFOA and PFOS values below the limit of detection (LOD) of 1.53 and 0.63 ng g-1 paper, respectively. Results of this study follow trends from 2005 to 2018 suggesting a reduction in PFOS and PFOA concentrations in microwave packaging.
Assuntos
Ácidos Alcanossulfônicos/química , Caprilatos/química , Fluorocarbonos/química , Embalagem de Alimentos , Papel , Cromatografia Líquida , Poluentes Ambientais/análise , Etanol , Contaminação de Alimentos , Humanos , Extração Líquido-Líquido , Metanol , Micro-Ondas , UltrassomRESUMO
To meet the growing interest of utilizing microalgae biomass in the production of biofuels and nutraceutical and pharmaceutical lipids, we need suitable analytical methods and a comprehensive database for their lipid components. The objective of the present work was to demonstrate methodology and provide data on fatty acid composition, lipid class content and composition, characteristics of the unsaponifiables, and type of chlorophylls of five microalgae. Microalgae lipids were fractionated into TAG, FFA, and polar lipids using TLC, and the composition of fatty acids in total lipids and in each lipid class, hydrocarbons, and sterols were determined by GC-MS. Glyco- and phospholipids were profiled by LC/ESI-MS. Chlorophylls and their related metabolites were qualified by LC/APCI-MS. The melting and crystallization profiles of microalgae total lipids and their esters were analyzed by DSC to evaluate their potential biofuel applications. Significant differences and complexities of lipid composition among the algae tested were observed. The compositional information is valuable for strain selection, downstream biomass fractionation, and utilization.
Assuntos
Lipídeos/análise , Microalgas/química , Biomassa , Varredura Diferencial de Calorimetria , Clorofila/análise , Cristalização , Ácidos Graxos/análise , Ácidos Graxos não Esterificados/análise , Glicolipídeos/análise , Fosfolipídeos/análise , Esteróis/análise , Triglicerídeos/análiseRESUMO
The superoxo complex Cr aq( (18)O (18)O) (2+) reacts with (CH 3) 3C(O) (16)O (16)O (*) to generate quantitative yields of mixed-label dioxygen, (18)O (16)O, demonstrating that this cross-reaction involves head-to-head interaction between the metal-activated and alkyl-activated dioxygen.