@article {2307, title = {Cyanobacterial copper-binding ligands isolated from artificial seawater cultures}, journal = {Marine Chemistry}, volume = {110}, number = {1-2}, year = {2008}, note = {ISI Document Delivery No.: 313BETimes Cited: 4Cited Reference Count: 34Wiramanaden, Cheryl I. E. Cullen, Jay T. Ross, Andrew R. S. Orians, Kristin J.}, month = {May}, pages = {28-41}, type = {Article}, abstract = {This paper demonstrates a method to isolate and characterise strong biogenic copper-binding ligands from an artificial seawater matrix. Pseudo-polarography is used to detect the ligands, determine their ionic strength-corrected binding constants, and track them through each step of the extraction process. Two ligand types are found, one strong and one relatively weak, with log K{\textquoteright} values of 49.4 +/- 1.1 and 19.8 +/- 5.5 respectively, assuming that the metal is bound as copper(II). If a copper(I) complex, the log K{\textquoteright} of the strong copper-binding ligand would be 25. Pseudo-polarography is then used to assess different resins for ligand extraction and to determine the eluent fraction in which the strong ligand is recovered. XAD-16 is found to be a suitable resin for extracting the strong binding ligand from salt water into methanol, suggesting that the ligand is weakly hydrophobic. As ligands are identified by their complexation of copper, no assumptions are made regarding the functional groups of these natural ligands. The copper-binding ligands are successfully extracted into solvents suitable for mass spectrometric analysis using soft ionisation methods such as electrospray and MALDI. (C) 2008 Elsevier B.V. All rights reserved.}, keywords = {AFFINITY-CHROMATOGRAPHY, chemical speciation, COMPETITION TECHNIQUE, COMPLEXING LIGANDS, copper, CU STRESS, EMILIANIA-HUXLEYI, IONIZATION MASS-SPECTROMETRY, LIGANDS, mass, NORTH PACIFIC, ORGANIC-COMPLEXES, polarography, SARGASSO SEA, sea water, SPECTROMETRY, TRACE-METALS}, isbn = {0304-4203}, url = {://000256715300004}, author = {Wiramanaden, C. I. E. and Cullen, J. T. and Ross, A. R. S. and Orians, K. J.} } @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 = {://000086527500011}, author = {Ross, A. R. S. and Ikonomou, M. G. and Orians, K. J.} }