Studies of the analytical potentialities of ammonium diethyldithiophosphate in inductively coupled plasma mass spectrometry by using solid phase extraction and flow-injection analysis.

Abstract

Complexation with ammonium diethyldithiophosphate (ADTP) and sorption on a C-18 bonded silica gel minicolumn in flow system was exploited for on-line separation and preconcentration in inductively coupled plasma mass spectrometry. Influence of interaction time between metallic ions and ligand, ligand concentration, nature and concentration of acid, timing, flow rates and minimization of spectral interference due to sodium were studied. Metallic complexes were stripped from the solution and retained in the minicolumn. Other ions that do not form complexes pass through the column promoting the separation of the matrix. Selectivity was improved with sequential elution. Water or 2% (v/v) HNO3 solution can be used for minicolumn washing before analyte elution with ethanol. When samples with sodium content up to 5000 mo. L-1 were directly analysed in system, Cu-63 apparent concentration of only 0.45 mu g L-1 was detected, while no interference were observed for As, Pb, Bi, Se, In, Tl, Cd, Hg and Cu-65. For 0.25% w/v ADTP and 3 mt sample volume in 2% (v/v) HNO3 analytical curves for Bi, Cu, Pb, As, Se, In, Tl, Cd, Hg in the 0. 10-2. 00 mu g L-1 range were obtained (r > 0.998). Sampling rate and detection limit depend on the selected conditions for concentration and elution. Detection limits for Cu, As, Se, Cd, In, Hg, Tl Pb and Bi were 0,014, 0.27, 0.06, 0.02, 0.29, 0.43, 0.02, 0.06 and 0.002 mu g L-1, respectively.