Rosende María, Magalhães Luis M, Segundo Marcela A, Miró Manuel
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.
REQUIMTE, Department of Chemistry, Faculty of Pharmacy, University of Porto, R. de Jorge Viterbo Ferreira, 228, Porto 4050-313, Portugal.
Anal Chim Acta. 2014 Sep 9;842:1-10. doi: 10.1016/j.aca.2014.06.033. Epub 2014 Jun 23.
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.
本文提出了一种新型仿生提取方法，该方法能够在线处理≥400mg的固体基质，以便根据ISO规范的建议，在最坏情况下自动确定土壤中微量元素（TE）的生物可及性。首次以动态形式评估了一种类似统一生物可及性/生物可利用性比（UBM）的基于生理学的提取试验，通过将混合流动装置与电感耦合等离子体原子发射光谱仪在线联用，准确评估森林土壤和住宅花园土壤中铬、铜、镍、铅和锌的体外生物可及性。深入研究了三种模拟生物相关的操作提取模式：（i）单独进行胃液提取；（ii）以单向流动提取形式进行唾液和胃液复合提取；（iii）以循环模式进行唾液和胃液复合提取。事实证明，使用消化液的三种配置的提取曲线符合一级反应动力学模型，用于估计最大TE生物可及性，即人类风险评估协议中的实际最坏情况。采用全因子设计，选择样品量（400-800mg）、萃取剂流速（0.5-1.5mL min⁻¹）和萃取温度（27-37°C）作为变量进行多变量优化研究，以获得最大的TE萃取率。分析了两种理化性质不同的土壤，在0.05显著性水平下，胃液中TE浸出浓度与残留部分之和与微波消解测定的所有被测金属总浓度之间未发现显著差异。这些结果表明了使用消化液的自动仿生提取方法的可靠性和无偏差性（准确性）。
