Microwave-assisted Acid Extraction Methodology for Trace Elements Determination in Mastic Gum of Pistacia lentiscus Using Inductively Coupled Plasma Atomic Emission Spectrometry

Introduction - To ensure food safety, accurate knowledge of the levels of several trace elements is necessary. This is also true for natural products of plants and resins used for human consumption or therapeutic treatment, like the mastic gum of Pistacia Ientiscus. The rapid analysis of gum and resin matrices is a challenge because there are problems with the decomposition of such complicated matrices. Objective - To develop an efficient multielemental analytical method for the determination of trace elements and to compare different procedures for analyte extraction when microwave-assisted digestion is applied. Methodology - The inductively coupled plasma atomic emission spectrometric (ICP-AES) technique was applied and the optimum ICP conditions like radiofrequency power, argon flow rate and nebuliser sample uptake flowrate were found. The microwave-assisted procedure was compared with that with conventional heating. Since mastic and resinous materials are difficult for dissolution and extraction of trace element, influential acid mixtures containing hydrofluoric acid proved to be capable of quantitative extraction of the analytes. Results - The digestion of mastic resin or similar matrices is significantly facilitated by using microwave radiation instead of conventional heating since the obtained recovery for several analytes is much higher. It was proved that the acid mixture of HCl-HNO3-HF was the most efficient for complete sample digestion and recovery of the analytes. Conclusions The performance characteristics of the developed method were evaluated against certified reference material and the method was proved reliable and applicable to the analysis of mastic gum and possibly to similar resinous matrices. Copyright (C) 2010 John Wiley & Sons, Ltd.