@article {4921,
	title = {Characterization of dissolved tannins and their metal-ion complexes by electrospray ionization mass spectrometry},
	journal = {Analytica Chimica Acta},
	volume = {411},
	number = {1-2},
	year = {2000},
	note = {ISI Document Delivery No.: 305EYTimes Cited: 25Cited Reference Count: 51},
	month = {May},
	pages = {91-102},
	type = {Article},
	abstract = {Electrospray mass spectrometry was used to characterize metal-complexing ligands derived from tannic acid, a component of natural dissolved organic matter. Complexes formed by tannin ligands with copper and other biogeochemically important metals were identified from the mass-to-charge ratios of the corresponding deprotonated molecular ions, allowing stoichiometry and metal oxidation state to be determined. Ligand ion intensities were proportional to tannic acid concentration, with detection limits on the order of 5 nM for individual compounds in 50:50 water/acetonitrile. The relative abundance of free ligand and complex ions indicated the degree of complexation under different solution conditions (metal concentration, pH, ionic strength). Using tandem mass spectrometry, the structure and principal copper binding site for one of the tannins were also determined, providing unique information with regard to metal complexation by these polyfunctional ligands. The technique can be combined with high performance liquid chromatography for on-line separation of dissolved organic compounds. Results demonstrate the potential of this approach for characterizing the different classes of metal-complexing ligands found in natural waters. (C) 2000 Elsevier Science B.V. All rights reserved.},
	keywords = {AFFINITY-CHROMATOGRAPHY, CHROMATOGRAPHY, COMPLEXATION, copper, electrospray ionization, high performance liquid, iron, LIGANDS, MASS SPECTROMETRY, metal-ion complexes, NATURAL ORGANIC-LIGANDS, ORGANIC, PERFORMANCE, PROTEINS, REGIOSELECTIVE MONO-OXIDATION, SPECIATION, STOICHIOMETRY, tannins, TOXICITY, trace metals},
	isbn = {0003-2670},
	url = {<Go to ISI>://000086527500011},
	author = {Ross, A. R. S. and Ikonomou, M. G. and Orians, K. J.}
}
@article {4348,
	title = {The determination of dissolved zirconium and hafnium from seawater using isotope dilution inductively coupled plasma mass spectrometry},
	journal = {Marine Chemistry},
	volume = {60},
	number = {3-4},
	year = {1998},
	note = {ISI Document Delivery No.: ZR467Times Cited: 23Cited Reference Count: 22},
	month = {Apr},
	pages = {245-255},
	type = {Article},
	abstract = {This paper describes the development of an analytical technique utilizing isotope dilution and inductively coupled plasma mass spectrometry (ICP/MS) to determine the picomolar and femtomolar concentrations of dissolved Zr and Hf found in seawater. Data acquired using this technique are presented to verify the method; in the subarctic North Pacific Zr ranges from 25 to 366 pmol/kg and Hf from 0.20 to 1.02 pmol/kg, with concentrations increasing smoothly with depth. The chelating ion-exchange resin, Chelex-100, was found to be suitable for the extraction/concentration step required for the determination of dissolved Zr and Hf in seawater using isotope dilution analysis. The extraction was optimized for pH, flow rate, resin volume, elution volume, and the time required for isotope equilibration. The isotope ratios Zr-91/Zr-90 and Hf-178/Hf-177 were measured using flow injection ICP/MS. The detection limits for a one litre sample are 0.21 and 0.03 pmol/kg for Zr and Hf, respectively. The analytical precision (Is) of the technique improves with increasing concentration and varies from 7\% at 42 pmol/kg to 2.5\% at 280 pmol/kg for Zr and from 22\% at 0.28 pmol/kg to 9\% at 1.4 pmol/kg for Hf. (C) 1998 Elsevier Science B.V.},
	keywords = {aluminum, ATLANTIC, ATOMIC-ABSORPTION SPECTROMETRY, Chelex-100, hafnium, ICP-MS, OCEAN, SEA-WATER, SEAWATER, trace metals, TRACE-METALS, ZIRCONIUM},
	isbn = {0304-4203},
	url = {<Go to ISI>://000073979800008},
	author = {McKelvey, B. A. and Orians, K. J.}
}
