Determination of arsenic in plant samples by inductively coupled plasma atomic emission spectrometry with ultrasonic nebulization: a complex problem

Under well-defined conditions, the analysis of most trace elements by induc tively coupled plasma atomic emission spectrometry with ultrasonic nebuliza tion (ICP-AES-USN) leads to accurate results for environmental matrices usu ally studied. Due to differences in matrix composition between standards an d samples, ICP-AES-USN determinations of arsenic are interfered with by cha nges that take place mainly within the desolvation stage of the USN device. In this work, effects of plant matrices on the determination of As in six arsenic species have been investigated. Firstly, interferences were simulat ed by measuring analyte (species) signals in solutions containing variable concentrations of the main matrix elements encountered in mineralized plant samples (K, Ca, Mg, P and Na). Secondly, the influence of real plant matri ces on emission signals of arsenic species was also studied. In this case, the observed effects were different than for individual matrix elements con sidered separately: Ca and Mg always present in real samples efficiently co mpensate the undesirable effects. Validation of this statement has been per formed using mineralized plant reference materials. In addition, ICP-AES-US N results have been compared with those obtained by Zeeman electrothermal a tomic absorption spectrometry. (C) 2001 Elsevier Science B.V. All rights re served.