A cost-effective and rapid microwave-assisted acid extraction method for the multi-elemental analysis of sediments by ICP-AES and ICP-MS

Abstract

A very simple, cost-effective and rapid single-step microwave-assisted leaching procedure using screw-capped polypropylene (PP) tubes and a domestic microwave oven has been developed for the extraction of elements from sediments followed by their analysis using inductively coupled plasma spectrometric techniques (ICP-AES/ICP-MS). Parameters affecting the microwave-assisted extraction such as extractant concentration, microwave irradiation time, microwave power and sample amount were optimized to get quantitative recovery of elements by taking two certified reference materials: stream sediment GBW-7312 and marine sediment IAEA-433. The supernatant obtained upon centrifugation was used for analysis of various elements: Na, K, Ca, Mg, Fe, Al, Li, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Tl, Pb and Bi. Quantitative recoveries of elements of interest were obtained using a mixture of 30% HNO₃ + 5% HF with 30 s irradiation time at a microwave power of 640 W for <500 mg sample weight. The results obtained here were in good agreement with the certified values with an overall precision of better than 10%. The obtained results showed that the present method of microwave assisted leaching (employing 30% HNO₃ + 5% HF) of sediment reference materials without resorting to total digestion produced an efficient attack of the most important metal bearing mineral phases and the quantitative recoveries obtained here showed complete leaching of the elements of interest. The procedure is especially attractive as it requires a microwave irradiation time of less than a minute and is thus extremely rapid.