RESUMEN
A study has been made of mineral acid matrix interferences in trace element determinations and methods are described for the multi-element analysis of lichen and algae [biomonitors] using inductively Coupled Plasma Emission Spectrometry [ICP-AES]. Several calibration strategies were compared employing aqueous standards with and without acids using modified ICP instrumental parameters. There was marked depression in analyte signal intensity in all the measurements. It has been shown that signal depressions of up to 32% can be observed under normal operating conditions. The use of acid matrix-matched standards and internal standard for calibrations substantially reduced signal depression problem. The methods gave elemental recovery from 97.7 to 98.8%. The accuracy of the methods was assessed by analysing the certified lichen material from the International Atomic Energy Agency [IAEA]. Accurate results were obtained by using the above calibration strategy with improved precision