Aging effects on macadamia nut oil studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

High-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry is successfully used in the detailed molecular analysis of aged macadamia nut oils. The results are consistent with peroxide values, the current industry measure for rancidity, and provide detailed molecular information on the oxidative and hydrolytic degeneration of such oils. Mass analysis of macadamia oil samples stored for extended periods at 6 °C revealed that oils obtained by the cold press method are more susceptible to aging than those obtained using modified Soxhlet or accelerated solvent extraction methods.

Production and isolation of ligated metal(IV)-oxo ions by tandem mass spectrometry.

High valent metal(IV)-oxo species, [M(==O)(MeIm)(n)(OAc)](+) (M = Mn-Ni, MeIm = 1-methylimidazole, n = 1-2), which are relevant to biology and oxidative catalysis, were produced and isolated in gas-phase reactions of the metal(II) precursor ions [M(MeIm)(n)(OAc)](+) (M = Mn-Zn, n = 1-3) with ozone. The precursor ions [M(MeIm)(OAc)](+) and [M(MeIm)(2)(OAc)](+) were generated via collision-induced dissociation of the corresponding [M(MeIm)(3)(OAc)](+) ion. The dependence of ozone reactivity on metal and coordination number is discussed.

Gas-phase ion-molecule reactions of metal-carbide cations MCn+ (M=Y and La; n=2, 4, and 6) with benzene and cyclohexane investigated by FTICR mass spectrometry and DFT calculations.

Yttrium- and lanthanum-carbide cluster cations YC(n)(+) and LaC(n)(+) (n = 2, 4, and 6) are generated by laser ablation of carbonaceous material containing Y(2)O(3) or La(2)O(3). YC(2)(+), YC(4)(+), LaC(2)(+), LaC(4)(+), and LaC(6)(+) are selected to undergo gas-phase ion-molecule reactions with benzene and cyclohexane. The FTICR mass spectrometry study shows that the reactions of YC(2)(+) and LaC(2)(+) with benzene produce three main series of cluster ions.

Monitoring reagent modification of charged SnxOy nanoclusters using Fourier transform ion cyclotron mass spectrometry.

The ion-molecule reactions of laser-generated radical clusters SnxO(x+1)(-) (x = 1-6), SnxO(x-1)(+) (x = 1-6) and SnxOx(+) (x = 2, 3) with the reagents H2S and CH3OH have been investigated using FTICR-MS. For the hypermetallic cations SnxO(x-1)(+), the rates of the sulfur-for-oxygen substitution reactions with H2S appear to be sensitive to LDA/DFT-predicted oxygen binding modes, with mu3-O modes relatively inert with respect to mu-O conformations. The reactions of the hypometallic anions SnxO(x+1)(-) with H2S were dominated by proton transfer, although S-for-O substitution was observed to be kinetically competitive.

Stepwise synthesis of Gly-Gly-His on gold surfaces modified with mixed self-assembled monolayers.

Peptide-modified electrode surfaces have been shown to have excellent recognition properties for metal ions. An efficient method of screening a potential peptide for its selectivity for a given metal would involve the synthesis of the peptide directly on the electrode surface. This paper outlines a procedure in which the tripeptide Gly-Gly-His was synthesized one amino acid at a time on a gold surface modified with a self-assembled monolayer of the mixed alkanethiolates 3-mercaptopropionic acid (MPA) and 3-mercaptopropane (MP).

Analysis of self-assembled monolayer interfaces by electrospray mass spectrometry: a gentle approach.

A general mass spectrometry technique for the characterization of alkanethiol-modified surfaces is presented. Alkanethiol self-assembled onto a gold surface (in this case, peptides were attached to the gold surface via a thiolate bond) was reductively desorbed in 0.05 M KOH in the presence of octadecyl-derivatized silica gel.

Exploring the use of the tripeptide Gly-Gly-his as a selective recognition element for the fabrication of electrochemical copper sensors.

The modification of electrodes with the tripeptide Gly-Gly-His for the detection of copper in water samples is described in detail. The tripeptide modified electrode was prepared by first self-assembling 3-mercaptopropionic acid (MPA) onto the gold electrode followed by covalent attachment of the tripeptide to the self-assembled monolayer using carbodiimide coupling. The electrodes were characterized using electrochemistry, a newly developed mass-spectrometry method and quantum mechanical calculations.

Reactions of 29 Transition Metal Cations, in the Same Oxidation State and under the Same Gas-Phase Conditions, with Sulfur.

A total of 29 transition metals (all except Tc), all as ions M(+), have been reacted with gaseous S(8). The reactivities and reaction products provide a unique set of comparative data on a fundamental reaction of the elements. The results underlie the interpretation of many other processes and compounds in condensed phases.