@article {724,
	title = {Characterization of copper-complexing ligands in seawater using immobilized copper(Il)-ion affinity chromatography and electrospray ionization mass spectrometry},
	journal = {Marine Chemistry},
	volume = {83},
	number = {1-2},
	year = {2003},
	note = {ISI Document Delivery No.: 743RZTimes Cited: 13Cited Reference Count: 44Ocean Sciences Meeting 2002FEB 11-15, 2002HONOLULU, HAWAII},
	month = {Oct},
	pages = {47-58},
	type = {Proceedings Paper},
	abstract = {Electrochemical studies show that copper and other bioactive trace metals are associated almost exclusively with dissolved organic ligands in surface seawater. Some of these ligands may be released by photosynthetic marine organisms to control metal uptake. However, new analytical approaches are needed to determine the chemical composition and ecological significance of these compounds. We have combined immobilized metal-ion affinity chromatography (IMAC) with electrospray ionization mass spectrometry (ESI-MS) to selectively extract and characterize copper-complexing ligands in seawater. Samples taken from British Columbia coastal waters were filtered through mixed cellulose membranes (0.45 mum) using nitrogen overpressure. Compounds with an affinity for copper were then extracted using Cu(II)-IMAC and eluted in acidified seawater. The eluant was monitored using UV absorption (255 nm), which showed that IMAC extracts from river and surface waters contained the highest concentrations of U-V-absorbing organic matter. Fractions were collected and analyzed by flow-injection (FI) negative ion ESI-MS using a custom made XAD-16 column, which gave 82\% recovery and a detection limit of 1.6 pmol for salicylic acid in acidified seawater. Low-molecular-weight compounds containing nitrogen were detected in the IMAC extracts of highest UV absorbance. These compounds followed an elution profile similar to the corresponding UV chromatogram. Measured masses of 265 and 259 Da are consistent with peptides containing, respectively, one thiol and two primary amino groups, characteristics associated with copper-complexing ligands detected in marine algal cultures and surface seawater using other methods. However, the absence of positive ions under experimental conditions suggests that the extracted compounds are predominantly acidic, and may therefore be hydroxamic acids or other nitrogen-containing compounds. The use of alternative resins and FI solvents to improve recovery, increase ionization efficiency, and permit structural (MS/MS) analysis of compounds extracted by IMAC is now being investigated. (C) 2003 Elsevier B.V All rights reserved.},
	keywords = {CHROMATOGRAPHY, COMPLEXATION, CU, DISSOLVED COPPER, electrospray ionization, ESTUARINE WATER, iron, LIGANDS, marine environment, MARINE-BACTERIA, MASS SPECTROMETRY, OCEAN, organic compounds, ORGANIC-LIGANDS, PHYTOPLANKTON, SPECIATION, stress},
	isbn = {0304-4203},
	url = {<Go to ISI>://000186588500006},
	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.}
}
