Analysis of trace metals in water by in-situ sample pre-concentration combined with wavelength dispersive X-ray fluorescence spectroscopy and inductively coupled plasma-optical emission spectroscopy

Abstract

In this paper an earlier work on the use of poly(acrylamidoxime) cloth for use as a passive monitor for trace metals in water by characterizing the sorption of several metals onto the cloth using a continuous flow chamber is extended. The monitors consists of amidoxime chelating groups covalently bound to the surface of a textile encased in a common 35 mm slide holder. Placement of this device in the water to be sampled resulted in the uptake of heavy metals by the chelating groups. After removal of the monitor from water, the metals were analyzed using wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) as well as by acid extraction followed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Correlation between the two methods of analysis varied with maximum correlation of 0.99897 observed for Pb and a minimum correlation of 0.16512 for Mg. The order of the distribution coefficients for the seven metals tested was: Pb≥Cu>Zn>Cd>Mn>Fe>Mg, in agreement with the order of the stability constants for the amidoxime/hydroxamic acid group for the chelation of the same metals at a pH of 5, with the exception of Fe. Field testing of the monitors was also carried out and a comparison made between active sampling of river water and sampling with the monitors. Results indicated that semiquantitative analysis of trace metals in water may be performed using the passive monitors.