Confirmation of lead aminocarboxylic complex formation using electrospray ionization mass spectrometry and speciation by anion-exchange chromatography coupled with ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) and electrospray ionization mass spectrometry (ESI-MS) were used as complementary techniques to provide element and molecular information for aminocarboxylic lead species including [Pb(NTA)]1−, [Pb(HEDTA)]1−, [Pb(EDTA)]2− and [Pb(DTPA)]3−. ESI-MS was used to initially confirm the formation of lead aminocarboxylic complexes in solution and subsequently anion-change chromatography coupled with ICP-MS was used to speciate these complexes using a mobile phase containing 30 mM NH4H2PO4 at pH of 8.0. However, [Pb(NTA)]1− was not observed during chromatographic separation due to its poor stability. The species [Pb(HEDTA)]1−, [Pb(EDTA)]2− and [Pb(DTPA)]3− were separated within 15 min with reasonable resolution and detection limits ranging from 0.05 to 0.2 μg L−1 with simple direct injection of sample. The proposed method was used to speciate aminocarboxylic lead complexes in soil solution.