Micromethod for the analysis of the four commonly used antiepileptic drugs using a jet tube column

We describe a simple method for the determination of phenobarbital, diphenylhydantoin, carbamazepine, and primidone in serum, by use of gas-liquid chromatography with temperature programming. The methylated derivatives of these anticonvulsants were well resolved, as was 5-(p-methylphenyl)-5-phenylhydantoin, the internal standard. In this procedure we used the jet tube for separation of the drug from the serum. The proposed procedure requires only 100 μl of serum and can be done in less than 30 min. The lower limit of detection for each of the drugs is 0.5 mg/liter. Analytical recoveries of drug from serum were excellent and peak height and concentration were linearly related up to twice the toxic concentration for serum.     

High-energy irradiation of chlorinated hydrocarbons

The Lawrence Livermore National Laboratory (LLNL) and the Idaho National Engineering Laboratory (INEL) are jointly investigating the decomposition of chlorinated hydrocarbons using bremsstrahlung radiation produced by electron accelerators and gamma photons from spent reactor fuel. Experimental results demonstrate an exponential type decay of concentration with dose for volatile organic compounds (VOCs) in ground water and for both polychlorinated biphenyls (PCBs) and insecticides in organic solutions. Experiments were performed at several photon energies and dose rates with various initial concentrations. Mass balance analysis suggests complete mineralization of VOCs in ground water and indicates significant degradation of PCBs and insecticides to VOC type compounds in organic solutions.Work performed under the auspices of the U.S. Department of Energy, DOE Contract Nos. W-7405-ENG-48 and DE-AC07-76IDO1570.     

Low Reynolds number aerodynamics of free-to-roll low aspect ratio wings

The aerodynamics of thin, flat-plate wings of various planforms (rectangular, elliptical and Zimmerman) have been studied in free-to-roll experiments in a wind tunnel. Non-zero trim angles at low angles of attack, self-induced roll oscillations with increasing angle of attack and even autorotation in some cases were observed. The rectangular wings with round leading-edge had non-zero trim angles at low incidences due to the asymmetric development of the three-dimensional separation bubble at these low Reynolds numbers. With increasing angle of attack, the bubble increases in length and once reattachment is lost, large amplitude roll oscillations develop. The Strouhal number of the roll oscillations is of the order of 10⁻², which is in the same range as those expected for small aircraft experiencing atmospheric gusts. Velocity measurements revealed that variations in the strength of the vortices drove the rolling motion. At the mean roll angle, because of the time lag in the strength of the vortices, an asymmetric flow is generated, which results in a net rolling moment in the direction of the rolling motion.     

Vibrational spectroscopy of anionic nitrate complexes of UO22+ and Eu3+ isolated in the gas phase

Wavelength-selective infrared multiple photon photo-dissociation (IRMPD) was used to generate spectra of anionic nitrate complexes of UO(2)(2+) and Eu(3+) in the mid-infrared region. Similar spectral patterns were observed for both species, including splitting of the antisymmetric O-N-O stretch into high and low frequency components with the magnitude of the splitting consistent with attachment of nitrate to a strong Lewis acid center. The frequencies measured for [UO(2)(NO(3))(3)](-) were within a few cm(-1) of those measured in the condensed phase, the best agreement yet achieved for a comparison of IRMPD with condensed phase absorption spectra. In addition, experimentally-determined values were in good general agreement with those predicted by DFT calculations, especially for the antisymmetric UO(2) stretch. The spectrum from the [UO(2)(NO(3))(3)](-) was compared with that of [Eu(NO(3))(4)](-), which showed that nitrate was bound more strongly to the Eu(3+) metal center, consistent with its higher charge. The spectrum of a unique uranyl-oxo species having an elemental composition [UO(9)N(2)](-) was also acquired, that contained nitrate absorptions suggestive of a [UO(2)(NO(3))(2)(O)](-) structure; the spectrum lacked bands indicative of nitrite and superoxide that would be indicative of an alternative [UO(2)(NO(3))(NO(2))(O(2))](-) structure.     

Characterization of VX on concrete using ion trap secondary ionization mass spectrometry

The nerve agent VX (O-ethyl S-2-diisopropylaminoethyl methyl phosphonothiolate) was analyzed on the surface of concrete samples using an ion trap secondary ion mass spectrometer (IT-SIMS). It was found that VX could be detected down to an absolute quantity of 5 ng on a concrete chip, or to a surface coverage of 0.0004 monolayers on crushed concrete. To achieve these levels of detection, the m/z 268-->128 ion fragmentation was measured using MS2, where m/z 268 corresponds to [VX + H]+, and 128 corresponds to a diisopropylvinylammonium isomer, that is formed by the elimination of the phosphonothiolate moiety. Detection at these levels was accomplished by analyzing samples that had been recently exposed to VX, i.e., within an hour. When the VX-exposed concrete samples were aged, the SIMS signature for intact VX had disappeared, which signaled the degradation of the compound on the concrete surface. The VX signature was replaced by ions which are interpreted in terms of VX degradation products, which appear to be somewhat long lived on the concrete surface. These compounds include ethylmethylphosphonic acid (EMPA), diisopropyl taurine (DIPT), diisopropylaminoethanethiol (DESH), bis(diisopropylaminoethane) disulfide [(DES)2], and a particularly tenacious compound that may correspond to diisopropylvinylamine (DIVA), or an isomer thereof. It was found that the thiolamine-derived degradation products DIPT, DESH, and (DES)2 were removed with isopropyl alcohol extraction. However, the DIVA-related degradation product was observed to strongly adhere to the concrete surface for longer than one week. Although quantitation was not possible in this set of experiments, the results clearly show the rapid degradation of VX on concrete, as well as the surface sensitivity of the IT-SIMS for intact VX and its adsorptive degradation products.     

Generation of gas-phase VO2+, VOOH+, and VO2+-nitrile complex ions by electrospray ionization and collision-induced dissociation

Cationic metal species normally function as Lewis acids, accepting electron density from bound electron-donating ligands, but they can be induced to function as electron donors relative to dioxygen by careful control of the oxidation state and ligand field. In this study, cationic vanadium(IV) oxohydroxy complexes were induced to function as Lewis bases, as demonstrated by addition of O2 to an undercoordinated metal center. Gas-phase complex ions containing the vanadyl (VO2+), vanadyl hydroxide (VOOH+), or vanadium(V) dioxo (VO2+) cation and nitrile (acetonitrile, propionitrile, butyronitrile, or benzonitrile) ligands were generated by electrospray ionization (ESI) for study by multiple-stage tandem mass spectrometry. The principal species generated by ESI were complexes with the formula [VO(L)n]2+, where L represents the respective nitrile ligands and n=4 and 5. Collision-induced dissociation (CID) of [VO(L)5]2+ eliminated a single nitrile ligand to produce [VO(L)4]2+. Two distinct fragmentation pathways were observed for the subsequent dissociation of [VO(L)4]2+. The first involved the elimination of a second nitrile ligand to generate [VO(L)3]2+, which then added neutral H2O via an association reaction that occurred for all undercoordinated vanadium complexes. The second [UO(L)4]2+ fragmentation pathway led instead to the formation of [VOOH(L)2]+ through collisions with gas-phase H2O and concomitant losses of L and [L+H]+. CID of [VOOH(L)2]+ caused the elimination of a single nitrile ligand to generate [VOOH(L)]+, which rapidly added O2 (in addition to H2O) by a gas-phase association reaction. CID of [VONO3(L)2]+, generated from spray solutions created by mixing VOSO4 and Ba(NO3)2 (and precipitation of BaSO4), caused elimination of NO2 to produce [VO2(L)2]+. CID of [VO2(L)2]+ produced elimination of a single nitrile ligand to form [VO2(L)]+, a V(V) analogue to the O2-reactive V(IV) species [VOOH(L)]+; however, this V(V) complex was unreactive with O2, which indicates the requirement for an unpaired electron in the metal valence shell for O2 addition. In general, the [VO2(L)2]+ species required higher collisions energies to liberate the nitrile ligand, suggesting that they are more strongly bound than the [VOOH(L)2]+ counterparts.     

Binding of molecular O2 to di- and triligated [UO2]+

Gas-phase complexes containing dioxouranium(V) cations ([UO(2)](+)) ligated with two or three sigma-donating acetone ligands reacted with dioxygen to form [UO(2)(A)(2,3)(O(2))](+), where A is acetone. Collision-induced dissociation studies of [UO(2)(A)(3)(O(2))](+) showed initial loss of acetone, followed by elimination of O(2), which suggested that O(2) was bound more strongly than the third acetone ligand, but less strongly than the second. Similar behavior was observed for complexes in which water was substituted for acetone. Binding of dioxygen to [UO(2)](+) containing zero, one, or four ligands did not occur, nor did it occur for analogous ligated U(IV)O(2) or U(VI)O(2) ions. For example, only addition of acetone and/or H(2)O occurred for the U(VI) species [UO(2)OH](+), with the ligand addition cascade terminating in formation of [UO(2)OH(A)(3)](+). Similarly, the U(IV) species [UOOH](+) added donor ligands, which produced the mixed-ligand complex [UOOH(A)(3)(H(2)O)](+) as the preferred product at the longest reaction times accessible. Since dioxygen normally functions as an electron acceptor, an alternative mode for binding dioxygen to the cationic U(V)O(2) center is indicated that is dependent on the presence of an unpaired electron and donor ligands in the uranyl valence orbitals.