The purpose of the work presented here was to evaluate the influence of solution composition and analyte characteristics on responsiveness to analysis with negative ion electrospray ionization mass spectrometry. The responses of a series of structurally diverse acidic molecules were compared in various solvents. Response was generally observed to be higher in methanol than acetonitrile and response for all analytes was poorer when water was mixed with the organic solvent. A positive correlation between negative ion ESI-MS response and log P was observed when either acetonitrile or methanol was used as the electrospray solvent. This result was expected because analytes with significant nonpolar character should be particularly responsive to ESI-MS analysis due to their higher affinity for electrospray droplet surfaces. It was also predicted that highly acidic analytes would be most responsive to analysis with negative ion ESI-MS due to their tendency to form negative ions. However, for the analytes studied here, acidity was found not to have a consistent influence on ESI-MS response. Many of the highly acidic molecules were quite polar and, consequently, were poorly responsive. Furthermore, the deprotonated molecular ion was detected for a number of molecules with very high pKa values, which would not be expected to form negative ions in the bulk solution. Ultimately, these results indicate that acidity is not a conclusive parameter for prediction of the relative magnitudes of negative ion ESI-MS response among a diverse series of analytes. Analyte polarity does; however, appear to be useful for this purpose. (J Am Soc Mass Spectrom 2005, 16, 446 -455)

The fate of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) was studied in soil. Labeled glyphosate was used to be able to distinguish the measured quantities of glyphosate and AMPA from the background values since the soil was sampled in a field where glyphosate had been used formerly. After addition of labeled glyphosate, the disappearance of glyphosate and the formation and disappearance of AMPA were monitored. The resulting curves were fitted according to a new EU guideline. The best fit of the glyphosate degradation data was obtained using a first-order multi compartment (FOMC) model. DT(50) values of 9 days (glyphosate) and 32 days (AMPA) indicated relatively rapid degradation. After an aging period of 6 months, the leaching risk of each residue was determined by treating the soil with pure water or a phosphate solution (pH 6), to simulate rain over a non-fertilized or fertilized field, respectively. Significantly larger (p < 0.05) amounts of aged glyphosate and AMPA were extracted from the soil when phosphate solution was used as an extraction agent, compared with pure water. This indicates that the risk of leaching of aged glyphosate and AMPA residues from soil is greater in fertilized soil. The blank soil, to which 252 g glyphosate/ha was applied 21 months before this study, contained 0.81 ng glyphosate/g dry soil and 10.46 ng AMPA/g dry soil at the start of the study. Blank soil samples were used as controls without glyphosate addition. After incubation of the blank soil samples for 6 months, a significantly larger amount of AMPA was extracted from the soil treated with phosphate solution than from that treated with pure water. To determine the degree of uptake of aged glyphosate residues by crops growing in the soil, (14)C-labeled glyphosate was applied to soil 6.5 months prior to sowing rape and barley seeds. After 41 days, 0.006 +/- 0.002% and 0.005 +/- 0.001% of the applied radioactivity was measured in rape and barley, respectively.

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The aromatic hydrocarbons-anthracene, 9,10-diphenylanthracene, 1,2-benzanthracene, chrysene, coronene, and perylene-were observed to undergo two consecutive reversible one-electron transfers in several common electrolytic solvents to produce the anion radicals and the dianions, stable during the time scale of slow sweep cyclic voltammetry. The technique which allowed for the observation of the reversible reduction of the anion radicals involved carrying out voltammetric measurements in the presence of suspended neutral alumina which has the effect of keeping the solvents free of proton donors or other electrophilic impurities. Disproportionation equilibrium constants were found to be exceedingly small for all of the aromatic anion radicals in all of the solvents investigated. The values of the disproportionation equlibrium constants were found to be dependent on both the solvent and the nature of the counterion; however, both of these effects were small. On the other hand, the disproportionation constants for perylene and anthracene anion radicals were found to vary by a factor of 300 and 600, respectively, for a 100-fold change in supporting electrolyte concentration.

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No abstract

Anthracene, benzophenone, nitrobenzene, and several other simple aromatic compounds undergo two consecutive reversible one-electron transfers to give first the anion radical and then the dianion, both species being stable during the time scale of cyclic voltammetry in several electrophile-free solvents.

102 patients with myocardial infarction (MI) were examined by three clinicians, who independently recorded the following symptoms and signs: dyspnoea, a displaced apex beat, S3-gallop, rales, neck vein distension, hepatomegaly, and dependent oedema. Chest X-ray, radionuclide ventriculography, and (in 40 patients) right heart catheterization were carried out immediately after the physical examination. The clinicians frequently disagreed as to the presence of physical signs of heart failure in individuals. Moreover, these signs were of limited value in identifying patients with pulmonary vascular congestion on chest X-ray, reduced left or right radionuclide ventricular ejection fractions, enlarged ventricular volumes or haemodynamic evidence of ventricular dysfunction. We conclude that clinicians frequently disagree in the recognition of physical signs of heart failure, and that these signs have an unpredictable relationship to radiographic, radionuclide and haemodynamic measures of ventricular performance in patients with MI. Nevertheless, physical signs are useful in identifying patients with high risk of cardiac death.