Determination of mercury in biological materials by CV-AAS after wet digestion

The paper describes the determination of ultratrace concentrations of mercury in biological materials. Samples were digested in nitric acid under pressure in a polytetrafluoroethylene bomb. Mercury was determined in the digest solution by cold vapour atomic absorption spectrometry using stannous chloride reduction and two-stage gold amalgamation. The detection limit is 0.12 ng. Analysis of several certified reference materials yielded results in excellent agreement with the certified values. The results for blood serum of several subjects ranged from 0.2 to 0.8g 1^–1.Of the National Fund for Scientific Research (Belgium), to whom correspondence should be addressed     

Development and validation of a sandwich ELISA for the determination of potentially allergenic sesame (Sesamum indicum) in food

This paper presents a sandwich enzyme-linked immunosorbent assay (ELISA) that allows the determination of traces of sesame in food. Chicken anti-sesame antibodies, used as coating antibodies, and rabbit anti-sesame antibodies, used as secondary antibodies, were prepared by immunization with a protein extract of white, peeled sesame. The ELISA did not show any cross-reactivity with 19 food ingredients commonly found in sesame-containing foodstuffs such as seeds, nuts, and cereals. In whole grain bread, crisp toast, and snacks, the limit of detection (S/N = 3) was 0.5, 0.5, and 0.3 μg sesame protein/g, and the limit of quantification (S/N = 10) was 0.6, 0.8, and 1.4 μg sesame protein/g, respectively. The analysis of blank food matrices (whole grain bread, white bread, crisp toast, and snacks) spiked with sesame protein at four spike levels generally resulted in mean recoveries from 72% to 145%. In the case of spiking blank food matrices with sesame seeds, the ELISA proved to be more accurate for whole wheat cookies than for whole wheat bread.     

Radiation annealing studies in ion bombarded MgO

Abstract

The energy distributions of convoy electrons produced at glancing angle incidence of fast ions are studied with Classical Trajectory Monte Carlo (CTMC) calculations. The image potentials both of the ion and of the convoy electron are taken into account. For light ions, the acceleration of the convoy electron by the ion's image potential is depressed by the image potential of the convoy electron, while for heavy ions this effect is negligible.     

Effects of vacuum UV and UVC radiation on dry Escherichia coli plasmid pUC19 II. Mutational specificity at the lacZ gene

The mutational spectra at the lacZ gene, induced either by vacuum UV at 160 nm or UVC at 254 nm in vacuum-dried preparations of Escherichia coli plasmid pUC19 DNA, have been characterized from 72 E. coli-propagated mutants by DNA sequencing. In plasmids irradiated in vacuum, vacuum UV is five times more mutagenic than UVC. In the UV-induced mutants, base substitutions largely predominate, with GC → AT (G, guanine; C, cytosine; A, adenine; T, thymine) transitions being the most abundant type of base change for vacuum UV (61%) and UVC (47%). Most of the GC → AT transitions appear to occur at dipyrimidine sites, which are located at the non-transcribed DNA strand. Some, but not all, hot spots for GC → AT transitions are identical for vacuum UV and UVC. Frameshifts, resulting from a loss of the thymine residue, are specific for UVC (22%), and were not detected after treatent with vacuum UV. They occur predominantly at thymine runs of the transcribed DNA strand. Only a few deletions were detected following irradiation with vacuum UV (7.5%) and UVC (2%); however, their frequency is not enhanced compared with the spontaneous mutation spectrum. The data confirm the important role of base substitution mutations in UV-induced mutagenesis, which is not only valid for the UVC range, but extends towards the vacuum UV range.     

Recovery of iodide ions from geothermal water with silica with grafted alkylammonium groups

Effect of a number of factors (time of contact and mass ratio of phases, acidity and temperature of the medium, concentrations of macrocomponents of geothermal water) on the sorption recovery of iodide ions with 3-(octadecyldimethylammonio)propylsilica and 3-(trimethylammonio)propylsilica from aqueous solutions was studied. Sorption isotherms were discussed. The possibility of using 3-(octadecyldimethylammonio)-propylsilica for recovery of iodide ions from highly mineralized geothermal water was analyzed.     

Solid phase synthesis of substituted quinolin-2(1H)-one-3-carboxylic acids via an intramolecular Knoevenagel condensation

A solid phase synthesis of substituted quinolin-2(1H)-one-3-carboxylic acids is described. The products are formed in a two-step synthesis in which ortho-aminophenones are first coupled to malonic acid bound to the Wang Resin followed by ring closure via an intramolecular Knoevenagel condensation.     

Billion‐Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution

β‐nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β‐NMR has previously been successfully applied in the fields of nuclear and solid‐state physics. In this work, β‐NMR is applied, for the first time, to record an NMR spectrum for a species in solution. ³¹Mg β‐NMR spectra are measured for as few as 10⁷ magnesium ions in ionic liquid (EMIM‐Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β‐NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry.