Determination of the effects of humics on the preconcentration of trace elements from water: a comparison of four instrumental analytical techniques

The effects of humic substances on the determination of fifteen trace elements in natural waters were investigated for four instrumental methods and five preconcentration techniques. Inductively coupled argon plasma optical emission spectrometry (CP/OES), dc argon plasma optical emission spectrometry (DCP/OES) and energy dispersive X-ray spectrometry (EDS) following sample preconcentration were compared with conventional flame atomic absorption spectrometry (AAS). The preconcentration techniques utilized were: precipitation, chelation, ion-exchange and precipitation/absorption. AAS is considered the best method investigated but it suffers from the lack of simultaneous multielement determination capability. The plasma and X-ray methods have the advantage of simultaneous multielement analysis but their selectivity, accuracy and precision are not as good as AAS. Preconcentration coupled with X-ray spectrometry does offer the ability to perform trace metal speciation studies in contrast to the flame and plasma methods which analyze total element concentration