Using ammonium pyrrolidine dithiocarbamate as precipitant and iron as a carrier, ppb concentrations of the following elements
were coprecipitated from fresh water: vanadium, chromium, manganese, nickel, copper, zinc, selenium, mercury, and lead. Precipitates
were collected on membrane filters then element concentrations were determined using energy dispersive X-ray fluorescence
spectrometry. Calibration curves indicate sensitivities ranging from 0.4 ppb for V, Zn, As and Hg to 1.2 ppb for Pb. It is
likely that this method of preconcentration can be directly incorporated into field sampling procedures, thus eliminating
the problems of sample contamination or trace element losses by absorption on container walls.