Novel glutathione conjugates of phenyl isocyanate identified by ultra‐performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance

Phenyl isocyanate is a highly reactive compound that is used as a reagent in organic synthesis and in the production of polyurethanes. The potential for extensive occupational exposure to this compound makes it important to elucidate its reactivity towards different nucleophiles and potential targets in the body. In vitro reactions between glutathione and phenyl isocyanate were studied. Three adducts of glutathione with phenyl isocyanate were identified using ultra‐performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance (NMR). Mass spectrometric data for these adducts have not previously been reported. Nucleophilic attack on phenyl isocyanate occurred via either the cysteinyl thiol group or the glutamic acid α‐amino group of glutathione. In addition, a double adduct was formed by the reaction of both these moieties. NMR analysis confirmed the proposed structure of the double adduct, which has not previously been described. These results suggest that phenyl isocyanate may react with free cysteines, the α‐amino group and also with lysine residues whose side chain contains a primary amine. Copyright © 2014 John Wiley & Sons, Ltd.     

Laser-frequency stabilization using forward scattering

Frequency stabilization of a single-mode dye laser is demonstrated using a simple magneto-optical forward scattering method. The dye laser was locked to the 2p₄–3s_s2, = 633 nm neon transition. Heterodyne beat-frequency measurements against a¹²⁷I₂-He-Ne meter standard laser showed a frequency stability of a few MHz.     

Evaluation of an automated thermospray liquid chromatography-mass spectrometry system for quantitative use in bioanalytical chemistry.

An automated thermospray liquid chromatography-mass spectrometry system is described, including an autosampler and a gradient liquid chromatography system controlled from the mass spectrometer data system. The performance and reliability of the equipment during unattended operation were evaluated by repeated injections of standard solutions of some antiasthmatic drugs, using deuterium-labelled analogues as internal standards. High sensitivity and reproducibility were achieved during a 19-hour run, incorporating gradient elution and a total of 54 injections. The relative standard deviation of the peak area measurement of the internal standards was in the range of 6.5-8.2%. The corticosteroid budesonide can be routinely measured in plasma down to 0.1 nmol/l. Direct injection of a small plasma volume into the thermospray liquid chromatography-mass spectrometry system could be used to monitor drug plasma levels during a toxicity study in dogs.     

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.     

Synthesis and structural studies of Sr2Co2−xGaxO5, 0.3?x?0.8

The novel oxide Sr₂Co_2−xGa_xO₅ with brownmillerite-type structure has been synthesized in the compositional range 0.3?x?0.8. Rietveld refinements using neutron powder diffraction data have been performed for the end compositions, x=0.3 and 0.8. The structure is best described in the space-group Icmm (no. 74) with unit cell parameters a=5.5678(6), 5.6126(7) Å, b=15.749(2), 15.733(2) Å and c=5.4599(6), 5.4559(7) Å for the x=0.3 and 0.8 compositions, respectively. The compounds were found to be G-type antiferromagnetic with the magnetic moments parallel to the c-axis. High-temperature magnetic susceptibility measurements confirmed the samples to be antiferromagnetic with Néel temperatures T_N=505, 468 and 423 K for the x=0.3, 0.5 and 0.8 samples, respectively. High-resolution transmission electron microscopy and electron diffraction studies confirmed the I-centred structure and revealed the presence of disorder.     

Detection of irradiated foods by luminescence of contaminating minerals—effect of mineral composition on luminescence intensity

Laboratory irradiated rock and mineral samples were studied for their luminescence properties. The effect of alteration of feldspars on luminescence intensity was determined by the autoradiographic method for porphyritic granodiorite planar rock samples and with the TL reader for crushed minerals. Feldspars and quartz exhibited more intensive luminescence than mafic minerals, and luminescence of fresh K feldspar was the most intense. Potassium concentration did not have any effect on luminescence intensity for K feldspars but the intensity was highly dependent on the alteration degree of the mineral. Decrease in luminescence was found without a change in the element composition of the mineral and alteration was due to sericitization of K feldspar.     

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