Speeding up HCl extractions by employing ultrasound energy to evaluate trace elements bioavailability in sediments

Abstract

Uma análise de variância de três fatores foi usada para testar a significância do tipo de recipiente, tipo de material e número de replicatas na preparação de amostras de sedimento utilizando um banho ultra-sônico. A extração convencional com HCl 1,0 mol L -1 , por 0,5, 4 e 12 h, foi modificada, e o banho ultra-sônico foi aplicado para diminuir o tempo de preparo de amostras. Os metais traço foram medidos por ICP OES. Os melhores resultados foram obtidos com frascos de Teflon ® com base plana. Com exceção do Ni, constatou-se que é possível trabalhar no banho de ultrasom em triplicatas, sem comprometer a eficiência e/ou precisão da extração. A eficiência de extração melhorou com o aumento no tempo de sonicação de 1 para 50 min. Para a maioria dos elementos, a extração assistida por radiação ultra-sônica pode reduzir o tempo convencional de extração de 12 h para 50 min ou menos (i.e. 6 min para Pb). A precisão obtida foi comparável aos valores obtidos com a extração convencional. O método proposto é rápido, barato e uma boa alternativa para o levantamento da biodisponibilidade e potencial de mobilidade de metais em sedimentos.A three factors analysis of variance was used to test the significance of the type of vessel, the type of material and the number of replicates in the preparation of sediment samples using an ultrasonic bath. The conventional extraction with HCl 1.0 mol L -1 , for 0.5, 4 and 12 h, has been modified, applying an ultrasonic bath, in order to speeding up the sample preparation time. Trace metals were measured by an ICP OES. The best results were obtained using a Teflon ® vessel with a flat bottom. For all metals but Ni it was demonstrated the feasibility of working in triplicates in the ultrasonic bath, without compromising the efficiency and/or the precision of the extraction. Leaching efficiency enhanced with increasing sonication time from 1 to 50 min. For most elements the ultrasound-assisted leaching could reduce the conventional extraction time from 12 h to 50 min or even less (i.e. 6 min for Pb). The precision obtained was comparable to values obtained for the conventional acid extraction. The proposed method is a fast, inexpensive and easy alternative for screening of the potential mobility and bioavailability of metals in sediments.

Syrah grape skin valorisation using ultrasound‐assisted extraction: Phenolic compounds recovery, antioxidant capacity and phenolic profile

“…With the bubbles implosion, there is a greater diffusivity of the solvent into the matrix. In addition, the ultrasound energy induces acoustic cavitation, which promotes an increase in temperature and pressure, which, with fragmentation by the shock waves, can increase the mass transfer of the analyte to the solvent (Hatje et al, 2009). Therefore, the use of this technology can lead to a better extraction of the compounds present in the matrix.…”

Increase in the bioavailability of trace metals after sediment resuspension

“…According to Morse [38], the extraction in HCl 1 mol L −1 comprises the reactive phase of the metals, that is, the potentially more bioavailable. Huerta-Diaz and Morse [23], Townsend et al [52], Hatje et al [20], Machado et al [31], Peña-Icart et al [42] and Monte et al [36] also mention that this extraction is widely used in the determination of the bioavailability of metals in sediments.…”

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“…Cavalcante et al 131 compared extraction techniques and clean-up procedures for PAH's analysis in sediments of the Ceará State (Brazil) coast and they observed that the highest recoveries were obtained with soxhlet and ultrasonic techniques. Hatje et al 132 investigated trace elements extractions with hydrochloric acid using factorial design. The authors concluded that the ultrasound-assisted leaching could reduce the conventional extraction time from 12 h to 50 min or even less (for Pb, for example).…”