A nitric acid–hydrogen peroxide digestion method for trace element analysis of milligram amounts of plankton and periphyton by total-reflection X-ray fluorescence spectrometry

Abstract

A wet digestion method is presented for trace element determination in minute plankton and periphyton samples of mass 500 µg–100 mg. Nitric acid and hydrogen peroxide are used at 100°C to provide nearly complete digestion within a few hours. Samples of a certified reference material of plankton powder (CRM 414) were digested and analysed by total-reflection X-ray fluorescence (TXRF) spectrometry. Reasonable accuracy and precision were obtained for 10 biologically essential trace elements (Ti, Mn, Fe, Ni, Cu, Zn, Se, Rb, Sr and Pb) and for four bulk elements (P, S, K and Ca). Recoveries were between 70 and 130% and the relative standard deviations were ≤20% for all of these elements except P and S. The method was applied in a study of natural periphyton communities from 13 locations in European rivers and streams. Summarised data on the trace element contents of these communities are reported.