Development and validation of a hydrophilic interaction chromatography–tandem mass spectrometry for quantification of nicotine and its metabolites in human maternal and cord sera

A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd.     

Formation of a liquid organic ion associate in aqueous solution and its application to the GF-AAS determination of trace cadmium in environmental water as a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol

The formation of a liquid organic ion associate in an aqueous sample was applied to the concentration and determination of cadmium in environmental water samples. Cadmium was converted into a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (5-Br-PAPS) in a 40-mL sample solution, and was extracted into a liquid ion associate of phenolsulfonate and benzethonium during phase formation. More than 400-fold enrichment was easily attained by this technique, because the volume of the liquid organic phase formed was very small, ca. 2 microL. After dilution of the organic phase with a small volume of 2-methoxyethanol, the cadmium in the solution was determined by GF-AAS. The detection limit was 0.09 ng/L (3sigma(b)). This method was applied to the determination of cadmium in river water and seawater.     

Decompositions of measures on orthoalgebras and difference posets

We present a general decomposition theorem for elements of an ordered group with respect to a cone. This result enables us to obtain decompositions of finitely additive measures defined on quantum logics, orthoalgebras, or, more generally, on difference posets with values in Dedekind complete lattice ordered groups, with respect to a given cone of measures. In particular, we gain Yosida-Hewitt-type and Lebesgue-type decompositions.     

Duplicated ring enlargement of 4,9-methanothia[11]annulene to 6,11-methanothia[15]annulene

3,10-Dipyrrolidinyl-4,9-methanothia[11]annulene reacts with excess dimethyl acetylenedicarboxylate (DMAD) in refluxing toluene to give ring-enlarged 6,11-methanothia[15]annulene. X-ray crystallographic analysis of the product shows two different cis,trans-dienyl parts in the ring system. Product formation possibly involves π-facial selective addition of the enamine with DMAD and torque-selective ring opening of the intermediate cyclobutenes.     

Linearity condition for orbital energies in density functional theory: construction of orbital-specific hybrid functional

This study proposes a novel approach to construct the orbital-specific (OS) hybrid exchange-correlation functional by imposing the linearity condition: ?(2)E/?f(i)(2)|(0≤f(i)≤1) = ??(i)/?f(i)|(0≤f(i)≤1) = 0, where E, ε(i), and f(i) represent the total energy, orbital energy, and occupation number of the ith orbital. The OS hybrid exchange-correlation functional, of which the OS Hartree-Fock exchange (HFx) portion is determined by the linearity condition, reasonably reproduces the ionization potentials not only from valence orbitals but also from core ones in a sense of Koopmans' theorem. The obtained short-range HFx portions are consistent with the parameters empirically determined in core-valence-Rydberg-Becke-3-parameter-Lee-Yang-Parr hybrid functional [Nakata et al., J. Chem. Phys., 124, 094105 (2006); ibid, 125, 064109 (2006)].     

Development of quality assessment method for optically active food flavor chemicals

A quality assessment method for commercially available, optically active flavor compounds, namely, menthol, menthyl acetate, borneol, perillaldehyde, and 1,8-cineol, was developed. A gas chromatograph equipped with a flame ionization detector and a DB-5ms capillary column was used for the chemical purity test. A GC/MS with a beta-DEX cyclodextrin column was used for the optical purity test, by which the enantiomeric separation of each flavor compound was achieved. Enantiomeric excess was calculated as an expression of optical purity. Of the 25 standard samples subjected to the chemical purity test, six were found to have lower purity than the data provided by the manufacturers. When the same samples were subjected to the optical purity test, 11 were found to have lower purity than that indicated on the reagent labels. These results suggest that there is a need to conduct an optical purity test, in addition to a chemical purity test, for the quality assessment of flavor standards.     

Determination of proline enantiomers in honey and royal jelly by LC-UV

The chiral separation and quantification of D-proline and L-proline in honey and royal jelly were examined by LC with UV detection. Most of the endogenous compounds existing in honey, such as sugars, were removed by using SPE cartridges containing C18 and strong cation-exchange sorbent. Other components, such as primary amino acids, were also removed by two-step derivatization with o-phthalaldehyde (OPA) and 9-fluorenylmethyl chloroformate (FMOC-CI). The components that were derivatized with OPA were separated from proline with a C18 cartridge. Proline was then converted into an FMOC derivative that could be subsequently measured by LC-UV. Sufficient chiral separation of D-proline and L-proline was achieved with an LC chiral column made of a beta-cyclodextrin phase in the polar organic-phase mode. The average recoveries of D-proline and L-proline from honey and royal jelly were in the range of 81.3-98.6% (RSD of < 1.8%). When this method was applied to commercial honey and royal jelly samples, L-proline was detected at concentrations of 369-1930 microg/g, whereas D-proline was not detected.     

Laser-induced periodic surface structures formed on the sidewalls of microholes trepanned by a femtosecond laser

Laser-induced periodic surface structures (LIPSSs) were observed on the sidewalls of 300-μm-diameter holes trepanned on cemented tungsten carbide using femtosecond laser pulses at a wavelength of 800 nm. For a circularly polarized beam, LIPSSs were formed at a period of 300 nm and oriented perpendicularly to the plane of incidence on the sidewalls. For a linearly polarized beam, LIPSS formation was dependent on the relative angle α between the polarization direction and the plane of incidence. For relative angles α from 0° to 70° and from 110° to 180°, LIPSS spacing was 300 nm. However, there were two types of LIPSSs coexisting from 70° to 110°. One had a spacing of 120 nm and the other had a spacing that varied from 500 to 760 nm. It was found that the orientation angle of LIPSSs measured between the LIPSS orientation and the plane of incidence had a nonlinear dependence on α. To understand this dependence, a model was proposed in which LIPSSs are assumed to align perpendicularly to the direction of the absorbed electric field lying in the tangent plane of the sidewall of a drilled hole. The calculated results from this model showed good agreement with the experimental results.     

Reactions of bis(μ-diphenylamino)tetramethyldialuminum and μ-diphenylamino-μ-methyltetramethyldialuminum with trimethylamine,diethyl ether and dimethyl sulfide

The reactions of (μ-NPh₂)₂Al₂Me₄ and of μ-NPh₂ -μ-MeAl₂Me₄ with trimethylamine, diethyl ether and dimethyl sulfide have been investigated. These studies establish that the bases cleave the nitrogen bridged system (μ-NPh₂)₂ Al₂Me₄ to give adducts of formula Me₂Al(NPh₂) · B. The relative stabilities of the adducts formed appear to be in the order NMe > OEt₂ >SMe₂, with thesulfide adduct apparently dissociated even at ?74°. μ-NPh₂-μ-MeAl₂Me₄ reacts with a limited supply of base to give Me₃Al · B and (μ-NPh₂)₂ Al₂ Me₄, and additional base cleaves (μ-NPh₂)₂Al₂Me₄ as before.     

MoCu3TeO7Cl2·0.5H2O

Single crystals of molybdenum(VI) tricopper(II) tellurium(IV) hepta­oxide dichloride hemihydrate, MoCu₃TeO₇Cl₂·0.5H₂O, were synthesized via a transport reaction in sealed evacuated silica tubes. All atoms occupy general positions within the triclinic () unit cell. The building units are irregular CuO₄Cl and CuO₃Cl₂ square pyramids, distorted TeO₃₊₁E trigonal bipyramids (E is the lone pair of Te^IV) and irregular MoO₅ pyramids. The TeO₃₊₁E, CuO₄Cl and CuO₃Cl₂ polyhedra form (110) layers bridged by Mo atoms. The water mol­ecules are located in [100] channels.