title: Assessing oral bioaccessibility of trace elements in soils under worst-case scenarios by automated in-line dynamic extraction as a front end to inductively coupled plasma atomic emission spectrometry.
abstract: A novel biomimetic extraction procedure that allows for the in-line handing of ≥400 mg solid substrates is herein proposed for automatic ascertainment of trace element (TE) bioaccessibility in soils under worst-case conditions as per recommendations of ISO norms. A unified bioaccessibility/BARGE method (UBM)-like physiological-based extraction test is evaluated for the first time in a dynamic format for accurate assessment of in-vitro bioaccessibility of Cr, Cu, Ni, Pb and Zn in forest and residential-garden soils by on-line coupling of a hybrid flow set-up to inductively coupled plasma atomic emission spectrometry. Three biologically relevant operational extraction modes mimicking: (i) gastric juice extraction alone; (ii) saliva and gastric juice composite in unidirectional flow extraction format and (iii) saliva and gastric juice composite in a recirculation mode were thoroughly investigated. The extraction profiles of the three configurations using digestive fluids were proven to fit a first order reaction kinetic model for estimating the maximum TE bioaccessibility, that is, the actual worst-case scenario in human risk assessment protocols. A full factorial design, in which the sample amount (400-800 mg), the extractant flow rate (0.5-1.5 mL min(-1)) and the extraction temperature (27-37°C) were selected as variables for the multivariate optimization studies in order to obtain the maximum TE extractability. Two soils of varied physicochemical properties were analysed and no significant differences were found at the 0.05 significance level between the summation of leached concentrations of TE in gastric juice plus the residual fraction and the total concentration of the overall assayed metals determined by microwave digestion. These results showed the reliability and lack of bias (trueness) of the automatic biomimetic extraction approach using digestive juices.
authors.affiliation: FI-TRACE group, Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa, km 7.5, Palma de Mallorca, Illes Balears E-07122, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Rosende
authors.affiliation: REQUIMTE, Department of Chemistry, Faculty of Pharmacy, University of Porto, R. de Jorge Viterbo Ferreira, 228, Porto 4050-313, Portugal.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Magalhães
authors.affiliation: REQUIMTE, Department of Chemistry, Faculty of Pharmacy, University of Porto, R. de Jorge Viterbo Ferreira, 228, Porto 4050-313, Portugal.
authors.forename: Marcela A
authors.initials: MA
authors.lastname: Segundo
authors.affiliation: FI-TRACE group, Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa, km 7.5, Palma de Mallorca, Illes Balears E-07122, Spain. Electronic address: manuel.miro@uib.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Miró
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D005750:Gastric Juice / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction / Q000295:instrumentation; D014131:Trace Elements / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014131:Trace Elements
keywords: Automatic dynamic extraction; Inductively coupled plasma atomic emission spectrometry; Soils; Trace elements; UBM test; Worst-case conditions