Analysis of Metals in Marine Sediments by Microwave Extraction and Flame, Hydride Generation and Cold Vapour Atomic-Absorption Spectrometry

Abstract

A simple and fast metal extraction method that combines closed vessels and microwave heating for the simultaneous extraction of ten selected heavy metals (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Zn) from marine sediments is proposed. Digestion conditions, i.e. power and times microwave irradiation. reagent extractant, sample amount, were optimized to recover the potentially available metallic fraction not bound in silicates. A nitric acid and two step microwave program was established. The resulting solutions were analyzed by flame (FAAS), hydride generation (HGAAS) and cold vapour (CV-AAS) atomic absorption spectrometry. Quantifications were made using direct calibration with aqueous standards. The recoveries of the spiked samples investigated ranged from 89 to 113 %. The results obtained from analyzing the BCR certified reference sediment CRM 277 Estuarine Sediment were in good agreement with the certified values (93–105%), except for low values for chromium (79%). The relative standard deviations for the determination of metals were less than 4%. Finally, the technique designed herein was applied to sediment samples from La Coruña estuary, NW Spain.

Keywords :

• Heavy metals
• Sediments
• Pressurized microwave extraction
• Flame
• hydride generation and cold vapour atomic absorption spectrometry