Deuterated Form Research Articles

Determination of Gamma-hydroxybutyrate in Water and Human Urine by Solid Phase Microextraction-Gas Chromatography/Quadrupole Ion Trap Spectrometry

A simple method of detection was developed for gamma-hydroxybutyrate (GHB). The method involves the derivatization of GHB using a hexyl-chloroformate procedure in aqueous media (such as water or urine), extraction of the derivatization product directly from the sample using solid-phase microextraction, and subsequent separation and detection with gas chromatography quadrupole ion trap mass spectrometry. The deuterated form of GHB (GHB-D6) is used as an internal standard for quantitation. The method was linear for GHB-spiked pure water samples from 2 to 150 microg/mL GHB with a detection limit of 0.2 microg/mL. Spiked urine samples showed linearity from 5 to 500 microg/mL GHB with a detection limit of 2 microg/mL. The SPME-GC/MS method is applied to actual case samples, and the results are compared to those values obtained using a conventional GC/MS method. Sensitivity and linearity are comparable to those seen using traditional methods of separation, yet the SPME method is superior due to the simplicity, speed of analysis, reduction in solvent waste, and ability to differentiate between GHB and gamma-butyrolactone (GBL).

The Determination of Brønsted Acid Sites in Zeolite ERS-7 by Neutron and X-ray Powder Diffraction

The deuterated acid form of zeolite ERS-7 (Si/Al = 8.4) has been prepared by repeated cycles of D2O exposure and calcination. 27Al NMR data show that the relative proportions of tetrahedral and octahedral Al in the resulting material are 70 and 30%, respectively. Three Brønsted sites were identified by a combined Rietveld refinement that simultaneously employed synchrotron X-ray powder diffraction data and neutron powder diffraction data. Final lattice parameters were a = 9.7843(1) Å, b = 12.3676(1) Å, and c = 22.8336(2) Å, the combined Rwp factor was 6.3%, and χ2(reduced) was 1.48. Acid deuterons were located approximately 1 Å from oxygens O3, O5, and O7, with occupancy factors of 0.16(2), 0.16(3), and 0.18(2), respectively. These correpsond to 1.28(16), 0.64(12), and 1.44(16) deuterons per unit cell, respectively, for a total of 3.36(26) acid sites per unit cell, which is consistent with the tetrahedral Al content. Only deuteron D5 lies on a special position. T−O bond lengths suggest a site preference for Al at T4, T1, and possibly T2, each of which is bonded to at least one of the observed acid-site oxygens. A bridging framework oxygen site was identified in both the PND and PXD difference Fourier maps that appears to be disordered over at least two distinct sites; this corresponds to different local arrangements of Al at the neighboring T-sites. The out-of-plane framework hydroxyl tilt angles at each acid site were comparable to those of H+ SSZ-13 and D+ RHO. Acid site D7 demonstrated a significant in-plane hydroxyl tilt angle (7.5°), consistent with ab initio quantum mechanical calculations. This tilt clearly indicates an Al preference for site T4 over T6.

High resolution neutron fibre diffraction data on hydrogenated and deuterated cellulose

High-resolution fibre neutron diffraction data were recorded from cellulose samples on a D19 diffractometer at the Institut Laue-Langevin (Grenoble). Highly crystalline cellulose I samples from Cladophora (cellulose Iα+Iβ) or Halocynthia (cellulose Iβ) origin were prepared in the form of oriented films. Samples were studied in a hydrogenated form and in a hydrogen–deuterium exchanged deuterated form corresponding to all OH moieties being replaced by ODs. These samples, which diffracted to a resolution of around 0.9 Å, gave diffraction diagrams consisting of several hundred independent diffraction spots. Crystalline cellulose II fibres resulting from the mercerization of flax were also studied in a hydrogenated form using NaOH/H 2O as mercerizing medium and in a deuterated form using NaOD/D 2O. Both of these samples diffracted to around 1.2 Å, giving fibre diffraction diagrams slightly less resolved than those of cellulose I, but still consisting of more than one hundred independent diffraction spots. For cellulose I as well as for cellulose II, significant differences between the hydrogenated and deuterated patterns were observed and recorded. These new data should lead to improved structures for cellulose and direct identification of the position of hydrogen atoms involved in hydrogen bonding.

Deuterium isotope effect on miscibility of some binary mixtures containing acetonitrile or nitromethane

The liquid–liquid miscibility temperatures as a function of composition and deuterium substitution have been determined experimentally for the binary systems formed by acetonitrile or nitromethane with decanol and tetrachloroethylene including their deuterated forms. The following deuterated compounds were used: acetonitrile-d 3, nitromethane-d 3 and decanol-d 1. It appears that deuteration of the methyl group in acetonitrile or nitromethane leads to the significant upward shift of the upper critical solution temperature. This effect is discussed on the basis of the intermolecular interaction emphasizing the role of the strong dipole–dipole interaction between acetonitrile (or nitromethane) molecules. Deuterium substitution in OH group of decanol generates a weak downward shift of the upper critical solution temperature. It is believed that in this particular case the better miscibility upon deuterium substitution results from hydrophobic action of the large alkyl group obscuring the OH(D) group and restricting hydrogen bonding formation with this group.

Vibrational spectra of ammine–sulfito complexes of rhodium

Ambient and low temperature vibrational spectra of the known complex trans-Na[Rh(SO3)2(NH3)4]·2H2O (1) and the newly prepared fac-Na3[Rh(SO3)3(NH3)3]·2H2O (2) (both also in the deuterated form (1D) and (2D)) were measured and discussed. In both cases the spectra clearly show the effects of the real crystallographic symmetry of the complex entities.In accordance with the results of X-ray structure analyses of 1 and 2 the spectra reveal S-coordination of the sulfite ligands and consequently their trans-influence on the Rh–N bonds, also in terms of both valence vibration v(RhN4) and v(RhN3), respectively, and force constants f(Rh–N) derived from them.

Pharmacological uses and perspectives of heavy water and deuterated compounds

Since the discovery of D20 (heavy water) and its use as a moderator in nuclear reactors, its biological effects have been extensively, although seldom deeply, studied. This article reviews these effects on whole animals, animal cells, and microorganisms. Both "solvent isotope effects," those due to the special properties of D20 as a solvent, and "deuterium isotope effects" (DIE), which result when D replaces H in many biological molecules, are considered. The low toxicity of D20 toward mammals is reflected in its widespread use for measuring water spaces in humans and other animals. Higher concentrations (usually >20% of body weight) can be toxic to animals and animal cells. Effects on the nervous system and the liver and on formation of different blood cells have been noted. At the cellular level, D20 may affect mitosis and membrane function. Protozoa are able to withstand up to 70% D20. Algae and bacteria can adapt to grow in 100% D2O and can serve as sources of a large number of deuterated molecules. D2O increases heat stability of macromolecules but may decrease cellular heat stability, possibly as a result of inhibition of chaperonin formation. High D2O concentrations can reduce salt- and ethanol-induced hypertension in rats and protect mice from gamma irradation. Such concentrations are also used in boron neutron capture therapy to increase neutron penetration to boron compounds bound to malignant cells. D2O is more toxic to malignant than normal animal cells, but at concentrations too high for regular therapeutic use. D2O and deuterated drugs are widely used in studies of metabolism of drugs and toxic substances in humans and other animals. The deuterated forms of drugs often have different actions than the protonated forms. Some deuterated drugs show different transport processes. Most are more resistant to metabolic changes, especially those changes mediated by cytochrome P450 systems. Deuteration may also change the pathway of drug metabolism (metabolic switching). Changed metabolism may lead to increased duration of action and lower toxicity. It may also lead to lower activity, if the drug is normally changed to the active form in vivo. Deuteration can also lower the genotoxicity of the anticancer drug tamoxifen and other compounds. Deuteration increases effectiveness of long-chain fatty acids and fluoro-D-phenylalanine by preventing their breakdown by target microorganisms. A few deuterated antibiotics have been prepared, and their antimicrobial activity was found to be little changed. Their action on resistant bacteria has not been studied, but there is no reason to believe that they would be more effective against such bacteria. Insect resistance to insecticides is very often due to insecticide destruction through the cytochrome P450 system. Deuterated insecticides might well be more effective against resistant insects, but this potentially valuable possibility has not yet been studied.

Determination of nicarbazin in feeds using liquid chromatography-electrospray mass spectrometry.

A method is presented for the determination of the 4,4'-dinitrocarbanilide component of the coccidiostat nicarbazin in animal feeds. Samples are extracted by shaking with methanol and analysed, without further clean-up, using liquid chromatography-electrospray mass spectrometry. A deuterated form of the analyte is employed as internal standard to improve the repeatability of the method. The method has been validated at levels between 0.1 and 100 mg kg-1 with internal standard corrected recoveries between 88 and 101% and RSD values < 8%.

Thermodynamics of Mixing for Statistical Copolymers of Ethylene and α-Olefins

The melt-state interactions that govern phase behavior in polyolefin blends were evaluated by small-angle neutron scattering (SANS) and compared with earlier results for structurally similar model polymers. The materials are statistical copolymers of ethylene with a range of propylene, 1-butene, 1-hexene, and 1-octene contents, made by metallocene catalysis. They are modestly polydisperse (Mw/Mn ∼ 2) and not available in deuterated form, thus requiring modification of the procedures used for the nearly monodisperse and easily deuterated model polymers. The SANS intensity expression for polydisperse components was confirmed independently, and two experimental procedures, employing binary and ternary blends with deuterated model components, were used. The interactions obey a solubility-parameter formalism, in agreement with the earlier studies. Moreover, the values of δ − δref obtained for the α-olefin copolymers were found to depend only on w, the weight fraction of α-olefin comonomer. Finally, this δ − δr...

Adducts of hydrogen and methane with Os(II) and Os(IV) complexes: Theoretical analysis of (η 2-H 2)OsCl 2(PH 3) 2 and (η-CH 4)OsCl 2(PH 3) 2 molecular complexes by RHF, MP2 and DFT methods

A theoretical study of model OsCl 2(PH 3) 2 complex and its adducts with hydrogen and methane is reported. Geometry of two isomers of OsCl 2(PH 3) 2 complex and structures of possible σ complexes (η 2-H 2)OsCl 2(PH 3) 2, (η 2-CH 4)OsCl 2(PH 3) 2 have been calculated using density functional theory and MP2-method. It was shown that some isomers of weakly bonded hydrogen σ-complex OsH 2Cl 2(PH 3) 2 can form stable methane adducts followed by reductive elimination of hydrogen. Calculations of the reaction pathways for methane oxidative addition to isomers of 14-electron intermediate OsCl 2(PH 3) 2 have been performed. For the isomer active in this reaction, structures of the transition state and methylhydride product were calculated. Frequencies of vibrations of stable σ-complex (η 2-CH 4)OsCl 2(PH 3) 2 along with its deuterated form (η 2-CD 4)OsCl 2(PH 3) 2 have been computed in the MP2/LAN1DZ approximation.

How to Have Your Cake and Eat It Too

Scanning probe microscopies are now well-established methods for making images of molecules and materials at the atomic level. But now, scanning probe methods can also measure spectroscopic properties--the energy levels of molecules. In his Research Commentary, Pethica discusses results presented in the same issue by Stipe et al. in which a scanned probe was used to study vibrational states of molecules on surfaces. As a demonstration of the technique, the researchers were able to detect the energy shift of a deuterated form of acetylene. The combination of spatial and spectroscopic resolution should provide a powerful tool for surface scientists.

Vibronic structure in triatomic molecules: The hydrocarbon flame bands of the formyl radical (HCO). A theoretical study

A theoretical study of the vibrational structure of the X̃ 2A′ ground and B̃ 2A′ excited states of the formyl radical, HCO, and its deuterated form, DCO, has been performed. The potential energy surfaces have been computed by means of a multiconfigurational perturbative method, CASPT2. The computed geometries and the harmonic and anharmonic frequencies are successfully compared to the available experimental information. The vibrational intensities of the transition B̃ 2A′↔X̃ 2A′ have been computed both for absorption and emission. The results lead to accurate determinations of several structural parameters and some reassignments of the vibrational transitions of the so-called hydrocarbon flame bands of the formyl radical.

An experimental and quantum chemical vibrational study of normal and deuterated 1,1,1-trichlorodimethyl sulfide

1,1,1-trichlorodimethyl sulfide, CCl 3SCH 3, was studied as a liquid in its normal and deuterated forms using infrared and Raman techniques in the range 4000-50 cm −1. Optimized geometric parameters were obtained by means of Hartree-Fock and density functional methods, which served also to calculate the corresponding force field and normal modes of vibration. These theoretical results were used in the interpretation of the experimental measurements.

Localization of Adsorbed Cyclohexane in the Acid Form of Zeolite Y. A Powder Neutron Diffraction and Computational Study

The crystal structure of the deuterated acid form of zeolite Y with adsorbed cyclohexane (∼1 molecule/supercage) has been determined by powder neutron diffraction at 5 K. The structure was refined by the Rietveld least-squares method in the cubic space group Fd3m [a = 24.711(2) Å, Rp = 3.13%, Rwp = 4.28%]. Deuterium atoms were located, in order of decreasing occupancy, on O(3)[33(3)%], O(1)[10(2)%], O(4)[3(3)%] and O(2)[2(3)%]. Approximately half of the adsorbed cyclohexane molecules were located in the chair conformation in the 12-ring window. Energy minimization calculations predict various types of binding sites for cyclohexane in siliceous Y. One type of site is found in the 12-ring window and is in excellent agreement with the position determined from the diffraction analysis. Other binding sites in low-symmetry positions are predicted, where cyclohexane is coordinated to 4-ring and 6-ring windows; these could not be detected by the diffraction analysis. Our calculations suggest that cyclohexane molecules experience a rather flat potential surface in zeolite Y.

CO 2-laser photoacoustic spectroscopy of deuterated ammonia

Photoacoustic (PA) coincidence absorption spectra of ammonia and its deuterated forms with carbon-dioxide laser emission were obtained. In addition, a simple isotope synthesis procedure was developed for that purpose. The strongest coincidence for the NH 3 molecule was found with laser line 9R(30) at 1084.628 cm −1. Laser PA spectra of samples with different deuterium content indicate that coincidences with laser lines 10R(14) and 10R(30) at 971.93 and 982.10 cm −1, respectively, correspond to NH 2D, while one with 10R(20) at 975.93 cm −1 is attributed to NHD 2. The data obtained are discussed in relation to their uses in isotope chemistry and analysis. They are in agreement with results published by other authors.

Deuterated Methanol in the Orion Compact Ridge

We have investigated the chemistry of hot cores containing methanol, formaldehyde, and their deuterated forms. We have computed the D fractionation ratios attainable by the addition of H and D atoms to CO on cold grain surfaces. We can easily reproduce the observed HDCO/H2CO and D2CO/H2CO ratios but find that, as there is an additional path to CH2DOH, the CH2DOH/CH3OD ratio is typically 3. This result is in conflict with the conclusion of Jacq et al. that the observed gas-phase CH2DOH/CH3OD ratio of ≈ 1.1-1.5 in the Orion Compact Ridge source is consistent with their production in grain mantles. We show that, when these mantles are evaporated, the CH2DOH/CH3OD ratio can be altered by gas-phase reactions that preferentially form CH3OD via reaction of H2DO+ with CH3OH. We find that an unrealistically high HDO/H2O ratio of ≈ 0.1 is necessary to drive the CH2DOH/CH3OD ratio to within the observed range. Before concluding that the observed gas-phase CH2DOH/CH3OD ratio is inconsistent with these grain-surface reactions, we recommend that more accurate determinations of this ratio be made in the Compact Ridge and in other hot cores.

Vibrational spectra of new heteroleptic sulfito complexes of rhodium and iridium

Vibrational spectra of the known complex trans-Na[Rh(SO 3) 2(NH 3) 4]· nH 2O ( 1) and the newly prepared heteroleptic complexes cis-Na[Rh(SO 3) 2(NH 3) 4]·3H 2O ( 2; also in deuterated form ( 2D)), (NH 4) 5[IrCl 2(SO 3) 3(NH 3)]·2H 2O ( 3), and Na 3[IrCl 2(SO 3) 2(OH 2) 2]·7H 2O ( 4) were measured and discussed. In the case of complexes 1 and 2 the spectra allow clear distinction between the cis and trans forms. In accordance with the results of X-ray structure analyses of 2, 3, and 4 the spectral features reveal S-coordination of the sulfite ligands and consequently their trans influence, also in terms of force constants.

Infrared and Raman spectra and ab initio calculations for normal and deuterated trifluoromethanesulfonamide

Trifluoromethanesulfonamide, CF 3SO 2NH 2, was studied as a polycrystalline substance in its normal and deuterated forms using infrared and Raman techniques in the range 4000–50 cm −1. Ab initio calculations allowed the determination of the geometrical parameters of the molecule, and of the corresponding force field and normal modes of vibration. Such theoretical results served as a basis for an assignment of the spectral features.

7] Preparation of nonlabeled, tritiated, and deuterated pyridoxine 5′-β-d-glucoside and assay of pyridoxine-5′-β-d-glucoside hydrolase

Publisher Summary This chapter examines the biological synthesis based on the germination of peas and alfalfa for preparation of pyridoxine 5'- β -D-glucoside. The preparative methods discussed involve biological syntheses using germinating alfalfa seeds. These methods are advantageous in comparison to other potential methods of biosynthesis or chemical synthesis in terms of simplicity, convenience, and suitability for the preparation of nonlabeled, tritiated, and deuterated forms of pyridoxine 5'- β -D-glucoside. These synthetic methods and purifications provide various forms of pyridoxine 5'- β -D-glucoside in high purity and sufficient quantity for use in nutritional and biochemical studies. The partial availability of pyridoxine 5'- β -D-glucoside as a source of vitamin B 6 for mammals provides evidence of the existence of enzyme activity capable of hydrolyzing the β -glycosidic bond. Supernatant fractions of mammalian jejunal mucosa exhibit the ability to hydrolyze pyridoxine 5'- β -D-glucoside. In rats, jejunal pyridoxine-5'- β -D-glucoside hydrolase activity increases during vitamin B 6 deficiency. The microflora of rat jejunum also exhibits pyridoxine-5'- β -D-glucoside hydrolase activity, although this decreases during vitamin B 6 deficiency.

Theoretical calculation of photodetachment intensities for H3O−

We have calculated total and arrangement-selected photodetachment intensities for the H3O− anion (and its deuterated form, D3O−) using a Green’s function in a discrete variable representation with absorbing boundary conditions. A multiply-shifted quasiminimal residual method is used to obtain the Green’s function for many energies at once. We present spectra obtained by explicitly treating two and four degrees of freedom. Comparison with experiment indicates that the bending angles in the anion and neutral are more similar than in the current potential energy surfaces. The calculated spectra are also consistent with the suggestion that the barrier should be ‘‘earlier.’’

Accurate ab initio quartic force field and vibrational frequencies of the NH 4+ ion and its deuterated forms

The quartic force field of NH 4 + has been computed using advanced coupled cluster methods and a basis set of spdf quality. Effects of further basis set extension and of the inclusion of core correlation on the geometry and harmonic frequencies have been investigated. Our best computed values are: r e = 1.02029 A ̊ , ν 1 = 3236.6, ν 2 = 1690.1, ν 3 = 3345.1, and ν 4 = 1447.2 cm −1 , in excellent agreement with the experimental data. Complete sets of fundamentals and anharmonicity constants are reported for NH 3D +, NH 2D 2 +, NHD 3 +, and ND 4 +.