@article {2526, title = {Evolutionary algorithms to solve complicated NMR spectra}, journal = {Journal of Chemical Physics}, volume = {130}, number = {4}, year = {2009}, note = {ISI Document Delivery No.: 401TJTimes Cited: 3Cited Reference Count: 37Meerts, W. Leo de Lange, C. A. Weber, A. C. J. Burnell, E. E.}, month = {Jan}, pages = {8}, type = {Article}, abstract = {The complexity of H-1 NMR spectra of solutes in partially ordered solvents such as liquid crystals increases rapidly with the number of spins. Spectra of simple solutes with sufficient symmetry and containing not too many spins (typically <= 8) are readily analyzed. The analysis of larger spin systems is more difficult, and often impossible. In this paper we present the application of a general automated evolutionary algorithm to solve the highly complex proton NMR spectrum of the 12-spin system pentane, a solute that interconverts rapidly among several symmetry-unrelated conformations. The interpretation of the spectral parameters that are obtained from the analysis requires the use of a model to connect relative orientational orders in symmetry-unrelated conformers.}, keywords = {ALKYL CHAINS, AUTOMATED-ANALYSIS, evolutionary computation, HIGH-RESOLUTION NMR, liquid crystals, magnetic resonance, MOLECULAR-STRUCTURE, MULTIPLE-QUANTUM SPECTRA, NEMATIC LIQUID-CRYSTALS, ORDER, organic compounds, PROTON, SHAPE, SOLUTES, spectroscopy computing, STRATEGY}, isbn = {0021-9606}, url = {://000262965000028}, author = {Meerts, W. L. and de Lange, C. A. and Weber, A. C. J. and Burnell, E. E.} } @article {2302, title = {Experimental determination of the third derivative of G. I. Enthalpic interaction}, journal = {Journal of Chemical Physics}, volume = {129}, number = {21}, year = {2008}, note = {ISI Document Delivery No.: 379XWTimes Cited: 2Cited Reference Count: 19Westh, Peter Inaba, Akira Koga, Yoshikata}, month = {Dec}, pages = {4}, type = {Article}, abstract = {The solute (i)-solute interaction in terms of enthalpy, H-i-i(E)=N(partial derivative H-2(E)/partial derivative n(i)(2))=(1-x(i))(partial derivative H-2(E)/partial derivative n(i)partial derivative x(i)), the third derivative of G, was experimentally determined using a Thermal Activity Monitor isothermal titration calorimeter for aqueous solutions of 2-butoxyethanol (BE) and 1-propanol (1P). This was done using both calorimetric reference and sample vessels actively. We simultaneously titrate small and exactly equal amounts of solute i (=BE or 1P) into both cells which contain the binary mixtures at an average mole fraction, x(i), which differs by a small amount Delta x(i). The appropriate amount of titrant delta n(i) was chosen so that the quotient (delta H-E/delta n(i)) can be approximated as (partial derivative H-E/partial derivative n(i)), and so that the scatter of the results is reasonable. delta H-E is the thermal response from an individual cell on titration, and we measure directly the difference in the thermal response between the two cells, Delta(delta H-E). The resulting quotient, Delta(delta H-E)/delta n(i)/Delta x(i), can be approximated as (partial derivative H-2(E)/partial derivative n(i)partial derivative x(i)) and hence provides a direct experimental avenue for the enthalpy interaction function. We varied the value of Delta x(i) to seek its appropriate size. Since H-E contains the first derivative of G with respect to T, the result is the third derivative quantity. Thus we present here a third derivative quantity directly determined experimentally for the first time.}, keywords = {AQUEOUS-SOLUTIONS, calorimetry, DYNAMICS, enthalpy, fluctuations, H2O, HOFMEISTER SERIES, LIQUID MIXTURES, MOLECULAR-ORGANIZATION, organic compounds, SOLVATION, WATER}, isbn = {0021-9606}, url = {://000261430900001}, author = {Westh, P. and Inaba, A. and Koga,Yoshikata} } @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 = {://000186588500006}, author = {Ross, A. R. S. and Ikonomou, M. G. and Orians, K. J.} }