Ultrasound-assisted extraction procedure for the fast estimation of major, minor and trace elements in lichen and mussel samples by ICP-MS and ICP-AES

The application of ultrasound-assisted extraction procedure has been examined for the estimation of major, minor and trace elements in a set of bio-environmental samples (IAEA lichen 336 and mussel tissue NIST 2976) as a possible alternative to conventional digestion methods. Inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used for the quantification of the elements. Parameters affecting extraction such as extractant concentration, sonication time and ultrasound amplitude were optimized to get quantitative recovery of elements. These studies indicate that the method is a fast (within 15 min including centrifugation time) and simple method for the estimation of Na, K, Ca, Mg, Cr, Mn, Co, Ni, Cu, Zn, Ge, As, Se, Rb, Sr, Zr, Ag, Cd, In, Sb, Cs, Ba, Pb and Bi. Quantitative recoveries for most of the elements for which certified concentrations available, were obtained using a 1% (v/v) HNO3 as extractant and metal solubilization can be achieved within 4 min sonication time at 40% sonication amplitude and 100 mg sample weight. The supernatant obtained upon centrifugation was used for analysis. Quantitative recovery was achieved for many elements which are well in agreement with certified values. An overall precision of better than 10% could be achieved for many elements in multiple extractions. Similar extraction procedure was tested on two field lichen samples. Closed-microwave digestion method was also used for the estimation of various elements in lichen and mussel samples for comparison purposes.