Determination and confirmation of malachite green and leucomalachite green residues in salmon using liquid chromatography/mass spectrometry with no-discharge atmospheric pressure chemical ionization

A liquid chromatography/mass spectrometry (LC/MS) method was developed to quantitate and confirm residues of leucomalachite green (LMG) in salmon tissue after their conversion to chromic malachite green (MG) in the extraction process. The method uses no-discharge atmospheric pressure chemical ionization (APCI) in conjunction with an ion-trap instrument to generate product-ion spectra. In the sample preparation procedure, salmon tissue is extracted with acetonitrile/buffer, the LMG residue is partitioned into methylene chloride, the LMG is converted to MG using an organic oxidizing agent, and the MG is isolated on alumina/propylsulfonic acid solid-phase extraction cartridges. The method was validated by fortifying salmon with different levels of LMG, and then detecting the residue as MG The LC/MS conditions, including a comparison of electrospray and no-discharge APCI, were evaluated and optimized. MG was not confirmed in any of the control tissue extracts, and all fortified samples analyzed during validation met the confirmation criteria as described. In addition to providing confirmatory data, this method can provide an alternative method for quantitation of MG in salmon. The recoveries of LMG measured as MG by this LC/MS method, at fortification levels of 1-10 ng/g were very high (86-109%), with low relative standard deviation(RSD) values (6.4-13%). The results agreed very closely with those obtained for the same extracts using an LCNIS procedure, indicating that matrix suppression was not an issue. The presence of LMG in salmon tissue samples fortified at 0.25 ng/g was confirmed by this method, with an average recovery of 70.1% and an RSD of 12.0%. Sample extracts from fish exposed to MG were also analyzed.     

Dependence of the rate constants on the treatment of internal rotation modes: the reaction OH + CH3SH --> CH3S + H2O as an example

The title reaction has been used as an example to test the importance of using a hindered rotor treatment instead of a harmonic oscillator model for calculating vibrational partition functions corresponding to low-frequency internal rotation modes. First, a normal-mode analysis according to the Ayala and Schlegel's algorithm has been used to identify the internal rotation modes of methanethiol and the transition state structure. Then, after calculation of the energy barrier for each internal rotation, the corresponding hindered rotor partition functions have been calculated following the CW scheme of Chuang and Truhlar. The results show that the anharmonic treatment produces a rather modest improvement of the rate constants at room temperature or below.     

Complexation of the Non-steroidal Anti-inflammatory Drug Nabumetone with Modified and Unmodified Cyclodextrins

The inclusion of the anti-inflammatory drug, Nabumetone, in -, - and hydroxypropyl--cyclodextrin (CDs) is studied using UV-VIS absorption and steady-state fluorescence emission. Binding constants and thermodynamic parameters of complex formation are determined by spectrofluorimetry. The inclusion phenomena of Nabumetone with the three cyclodextrins is compared with that of the well known similar anti-inflammatory drug Naproxen. In the case of Nabumetone pronounced differences are observed in the complexation process with each cyclodextrin whereas the respective Naproxen complexes are nearly identical. ¹H-NMR experiments show that the inclusion process in Nabumetone can occur either through the substituents in the -2 (butanone) or -6 (methoxy) positions in the naphthalene ring.     

The existence of ferrous ferricyanide

Evidence in the literature on the synthesis of ferrous ferricyanide is critically discussed. Pyrolysis and pressure effects on Prussian Blue lead to ferrous ferrocyanide together with decomposition by-products, and not to ferrous ferricyanide. The latter compound could be a precursor in the formation of Turnbull's Blue or an excited state of Prussian Blue, but it is not a stable chemical species.     

Determination of propazine by differential pulse polarography in micellar and emulsified media

An electroanalytical study of the herbicide propazine's reduction process in micellar solutions and oil-in-water emulsions is reported. The anionic surfactant sodium pentanesulphonate was chosen as the most suitable. The differential pulse polarograms of micellar solutions had two reduction peaks below pH 2.0, whereas only one peak was obtained above pH 2.O. Ethyl acetate was chosen as the organic solvent to form propazine emulsions. Unlike in micellar solutions, the DPP polarograms of propazine emulsions showed only one peak even at pH < 2.0, suggesting that propazine hydrolysis was hindered in the emulsified medium. The limiting current is diffusion-controlled and the electrode process is irreversible. Propazine can be determined by differential pulse polarography over the 1.0 × 10^–1 – 1.0 × 10^–1moll^–1 and 1.0 × 10^–15 – 4.0 × 10^–1 moll^–1 concentration ranges and the limit of detection was 2.8 × 10^–1 moll^–1. Of the potential interferents simazine, methoprotryne and terbutryn (alls-triazines), thiram (a dithiocarbamate), dinoseb (nitrophenolic), and heptachlor (chlorinated cyclo-diene herbicide), only the first two were significant (10% error for equimolar concentrations). The method was applied to the determination of propazine in spiked drinking water. At a concentration level of 2.0 × 10^–1 moll^–1 a recovery of 94 ± 6% was obtained, after tenfold concentration on Sep-Pak.     

Kinematical and gravitational analysis of the rocket-borne clock experiment by Vessot and Levine using the revised Robertson's test theory of special relativity

The kinematic aspects of the rocket-borne clock experiment by Vessot and Levine are analyzed with the revised Robertson's test theory of special relativity (Found. Phys. 14, 625 (1984)). Besides the expected time-dilation, it is found that the intermediate steps of this experiment yield in principle Michelson-Morley type information (a relation between longitudinal and transverse length contractions) in the third order of the velocities involved, but no relativity-of-simultaneity related effects.The flat space-time test theory induces a family of spherically symmetric line elements that become the Schwarzschild line element in the relativistic case and also in theabinito rest frame of the theory. These line elements represent the same space-time manifold, but pertain in a one-to-one correspondence to the different flat space-time coordinate transformations of the test theory. The conserved energy is related to the family of local energies in the tangent plane. No deviations from the orthodoxy appear at the pertinent levels of approximation. Hence the unexplained residuals of the Vessot-Levine experiment are not due in obvious ways to kinematic and gravitational frequency shifts caused by deviations of the real coordinate transformations from the Lorentz transformations.This work was started while the author was at Departamento de Fisica, Facultad Experimental de Ciencias, Universidad del Zulia, Maracaibo, Venezuela. It was completed at the Department of Physics, Utah State University, Logan, Utah 83422.     

Revised Robertson's test theory of special relativity: Space-time structure and dynamics

The experimental testing of the Lorentz transformations is based on a family of sets of coordinate transformations that do not comply in general with the principle of equivalence of the inertial frames. The Lorentz and Galilean sets of transformations are the only member sets of the family that satisfy this principle. In the neighborhood of regular points of space-time, all members in the family are assumed to comply with local homogeneity of space-time and isotropy of space in at least one free-falling elevator, to be denoted as Robertson'sab initio rest frame [H. P. Robertson,Rev. Mod. Phys. 21, 378 (1949)].Without any further assumptions, it is shown that Robertson's rest frame becomes a preferred frame for all member sets of the Robertson family except for, again, Galilean and Einstein's relativities. If one now assumes the validity of Maxwell-Lorentz electrodynamics in the preferred frame, a different electrodynamics spontaneously emerges for each set of transformations. The flat space-time of relativity retains its relevance, which permits an obvious generalization, in a Robertson context, of Dirac's theory of the electron and Einstein's gravitation. The family of theories thus obtained constitutes a covering theory of relativistic physics.A technique is developed to move back and forth between Einstein's relativity and the different members of the family of theories. It permits great simplifications in the analysis of relativistic experiments with relevant Robertson's subfamilies. It is shown how to adapt the Clifford algebra version of standard physics for use with the covering theory and, in particular, with the covering Dirac theory.Part of this work was done at the Department of Physics, Utah State University, Logan, Utah 84322.     

The spherical-model limit in a random field

The spherical-model limitn of then-vector model in a random field, with either a statistically independent distribution or with long-range correlated random fields, is studied to demonstrate the correctness of the replica method in which then and replica limits limits are interchanged, provided the replica and thermodynamic limits are taken in the right order, in the case of long-range correlated random fields. A scaling form for the two-point correlation function relevant to the first-order phase transition below the lower critical dimensionality of the random system is also obtained.     

Molecular shape effects and quantum theory

Certain features of the chemist's molecular structure model, viz. size and shape, are retrieved even in the best non-adiabatic variational calculations thus far carried out for ground states of H ₂ ⁺ and H₂. Those features do not conflict with the full symmetry of exact molecular eigenstates, once they are properly understood as correlation effects.     

Development of a capillary electrophoretic method for the separation of diastereoisomers of a new human immunodeficiency virus protease inhibitor

A capillary electrophoretic (CE) method was developed for the separation of diastereoisomers of a new human immunodeficiency virus (HIV) protease inhibitor TMC114. In total 16 isomers of this drug have been synthesized (eight pairs of enantiomers). We succeeded in the separation of the eight diastereoisomers, but no enantiomers could be separated. Because of the high similarity and water-insolubility of these isomers, the separation is a real challenge. Different CE modes were tried out: capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), micellar electrokinetic capillary chromatography (MEKC), and microemulsion electrokinetic capillary chromatography (MEEKC). Only MEEKC offered resolution of these compounds.