Preconcentration and adsorption of metal chelates with analysis by direct sample insertion inductively coupled plasma atomic emission spectrometry

An automated preconcentration system that utilizes adsorption of 8-hydroxyquinoline (8-HQ) metal chelates onto a silica-C18 column has been evaluated. The metal chelates are desorbed with methanol and sprayed into an inductively heated graphite direct sample insertion cup. In this manner the organic solvent and much of the 8-HQ is removed and does not appear to cause interferences in the plasma. The detection limits of the current system are 8, 30, 60, 10, 9 and 40 parts per trillion for Cd, Cu, Fe, Mn, Pb and Zn, respectively, utilizing the reagents as purchased. Instrumental detection limits of 1, 0.2, 90, 0.3, 2 and 10 ppt for the same elements were calculated assuming that blank contamination can be eliminated.