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Solutions of the strong complexing agent ethylenediaminetetraacetic acid (EDTA) and Cu, Pb, Cd, AI, and Fe(III) were examined electrospray mass spectrometry (ES/MS). Uncomplexed EDTA and metaI-EDTA complexes survive the electrospray process intact and can be detected simultaneously by mass spectrometry. Best sensitivity was achieved in the positive ion mode in which EDTA and EDTAmetal complexes (present in solution as anions) were detected protonated species with a single positive charge. Except for the protonation, the aqueous metaI-EDTA complexes are preserved and neither fragmentation of complexes nor formation of clusters with more than one metal or iigand were observed in the mass spectra. Detection limits are between approximately 1 to 2 p~M for uncomplexed EDTA and for the Cu-EDTA and Pb-EDTA complexes, with a linear range up to 10 4 M. Calibrations based on solutions with eqnimolar concentrations of EDTA and Cu or Pb can be used to quantify EDTAmetal complexes in solutions with excess EDTA or metal, and in solutions with more than one metal present. Isotopic signatures of metals in the metal-ligand complexes are preserved, allowing the identification of the metal in a metaMigand complex. Isotopic signatures of metals can therefore aid in the identification of metaMigand complexes in unknown samples.

Two iron−chromate precipitates, KFe3(CrO4)2(OH)6 (the chromate analog of the sulfate mineral jarosite) and KFe(CrO4)2·2H2O, were discovered in a soil contaminated by chrome plating solutions. The precipitates were identified by electron microscopy and powder X-ray diffraction. KFe3(CrO4)2(OH)6 was found as small crystals interspersed within the bulk soil. KFe(CrO4)2·2H2O forms crusts in cracks and fractures of the soil. Powder X-ray diffraction of the whole soil indicates that most of the Cr(VI) in the soil is present as KFe3(CrO4)2(OH)6 and that the overall amount of KFe(CrO4)2·2H2O in the soil is relatively small. The reaction for the transformation between these two phases indicates that KFe(CrO4)2·2H2O is likely to form in more acidic , K+- and HCrO4 --rich environments than KFe3(CrO4)2(OH)6. Although both of these chromate phases have been synthesized and described, to our knowledge, this study is the first report of their occurrence in the environment.

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