A PRETREATMENT PROCESS FOR DETERMINATION OF MULTIPLE ELEMENTS IN PLANT SAMPLES BASED ON ICP-OES

The chemical composition of plants is as an important direct indicator in the geochemical survey and evaluation of agroecological environment. It is of great significance to accurately determine the element content of plant samples. The main purpose of this study is to develop an analytical process for the determination of multiple elements in plant samples using inductively coupled plasma optical emission spectrometry (ICP-OES) without the need for tedious sample pretreatment prior to spectroscopic determination. The plant samples are treated by three methods including microwave digestion, electrothermal plate digestion and ultrasonic digestion. The contents of Ca, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn in plant samples are determined respectively by ICP-OES, with comparison of digestion effects of the three methods. The results reveal that the detection limits of three methods are 0.042×10^-6-0.239×10^-6, 0.046×10^-6 -0.237×10^-6 and 0.026×10^-6-0.232×10^-6, respectively. The relative standard deviations of the elements to be measured are all lower than 10%, with the relative errors of -11% to +13.8%, -22.1% to +8.7%, and -13.3% to +8.9%, respectively. Ultrasonic digestion shows a lower detection limit and better accuracy, which meets the requirements of DD2005-03 Technical Requirements for Sample Analysis of Eco-geochemical Evaluation (Trial), and its feasibility in practice is verified. The test proves that dissolving samples in aquaregia with the assisted ultrasonic digestion is a simple, quick and accurate sample preparation method, which can meet the requirements of plant sample analysis.