title: Determination of trace elements in fluoropolymers after microwave-induced combustion.
abstract: An effective approach to the digestion of fluoropolymers for the determination of Ag, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, and Ni impurities has been developed using microwave-induced combustion (MIC) in closed quartz vessels pressurized with oxygen. Samples that were examined included the following: polytetrafluorethylene (PTFE); polytetrafluoroethylene with an additional modifier, perfluoropropylvinylether (PTFE-TFM); and fluorinated ethylene propylene (FEP). A quartz device was used as a sample holder, and the influence of the absorber solution was evaluated. Determination of trace elements was performed by inductively coupled plasma-optical emission and mass spectrometry. Neutron activation analysis (NAA) was used for validation purposes. Results were also compared to those obtained using microwave-assisted acid extraction in high-pressure closed systems. Dilute nitric acid (5 mol L(-1)), which was selected as the absorbing medium, was used to reflux the sample for 5 min after the combustion. Using these conditions, agreement for all analytes was better than 98% when compared to values determined by NAA. The residual carbon content in the digests was lower than 1%, illustrating the high efficiency of the method. Up to 8 samples could be digested within 30 min using MIC, providing a suitable throughput, taking into account the inertness of such samples.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, RS, Brazil. ericommf@gmail.com
authors.forename: Erico M M
authors.initials: EM
authors.lastname: Flores
authors.forename: Edson I
authors.initials: EI
authors.lastname: Muller
authors.forename: Fabio A
authors.initials: FA
authors.lastname: Duarte
authors.forename: Patricia
authors.initials: P
authors.lastname: Grinberg
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Sturgeon
mesh_terms: D013058:Mass Spectrometry; D008872:Microwaves; D009502:Neutrons; D017942:Nitric Acid / Q000737:chemistry; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry; D014131:Trace Elements / Q000032:analysis*
chemical_list: D014131:Trace Elements; D011791:Quartz; D017942:Nitric Acid; D011138:Polytetrafluoroethylene