bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated analysis of polar pesticides in water by on‐line solid phase extraction and gas chromatography using the co‐solvent effect
Authors: Noij Theo H. M. , van der Kooi Margo M. E. 
Published: May 2005

AbstractIn order to meet the requirements of analyzing very low concentrations of pesticides in water (typically at 0.1 μg/l or less), samples have to be concentrated prior to GC‐analysis. Samplie pre‐concentration by off‐line methods based on solid phase extraction (SPE) or liquid‐liquid extraction are very time consuming and cumbersome. Moreover, the quantitative performance of the analytical method as a whole in terms of accuracy and reliability is seriously hindered by elaborate, manually performed sample pre‐treatment steps. This paper describes an automated method based on solid phase extraction and capillary gas chromatography. The technique was applied for the analysis of 31 polar organophosphorus and organonitrogen pesticides. A commercially available HPLC/GC instrument is modified, using the LC‐part for solid phase extraction. The sample, of which only a few ml's is required to obtain sufficiently low detection limits, is delivered by a robotic large volume autosampler. After solid phase extraction and elution, the eluate is transferred into the GC via a so called “loop type interface”. In this paper the instrumentation and analytical methodology is described, as well as the main validation results. The quantitative performance (i.e. recovery and repeatability) of the most polar solutes like metamitron and dimethoate appears to be better than obtained with off‐line SPE as a result of the more beneficial ratio between the amount of sorbent and the sample volume. As the loop‐type interface causes losses of the most volatile compounds, a co‐solvent is added. This co‐solvent provides sufficient trapping capacity in the capillary pre‐columns to allow quantitative analysis of even the most volatile pesticides. Moreover a better separation of early eluting compounds is also established.
Enhanced selectivity in the determination of trianzines in environmental samples by Benchtop CGC‐MS‐MS
Authors: Sandra Pat , Beltran Joachim , David Frank 
Published: May 2005

AbstractSome triazines and metabolities have been analyzed in water and soil samples, at the 0.1 and 10 ppb level, respectively, by CGC‐MS and CGC‐MS‐MS using an ion trap detector (ITD). The sample preparation consisted of SPE on LiChrolut EN cartridges for water samples, and of ultrasonic treatment followed by SPE for soil samples. Recoveries were in the order of 90%. The advantage of MS‐MS compared to MS operation of the ITD, is the enhanced selectivity resulting in more precise determinations. The metabolites of atrazine and metribuzin have also been studied. Desethylatrazine and desamino‐metribuzin are the main metabolites.
In‐situ deactivation of packed columns for SFC
Authors: Zhang Shigang , Schindler Brigitte , Nicholson Graham , Bayer Ernst 
Published: May 2005

AbstractResidual adsorptive activity of reversed phase (RP) column packings used in supercritical fluid chromatography (SFC) can be significantly reduced by a dynamic in‐situ silanization with diphenyltetramethyldisilazane (DPTMDS). RP‐materials thus deactivated were characterized both chromatographically and by solid‐phase 29Si NMR.
Analysis of monoterpenes from conifer needles using solid phase microextraction
Authors: Schäfer Brit , Hennig Peter , Engewald Werner 
Published: May 2005

AbstractThe applicability of solid phase microextraction (SPME) to the headspace analysis of monoterpene hydrocarbons from conifer needles was examined. To this end, the influences of fiber coating thickness, exposure time, and exposure temperature on the enrichment of the different monoterpene hydrocarbons were investigated. The distribution constants between polydimethylsiloxane fiber and gas phase at a given temperature were found to be very different. A relation is therefore derived to calculate the distribution constants of substances not available from their Kováts retention indices. A slightly different approach could be the use of so‐called “relative distribution factors”, not considering the actual volume of fiber coating. In view of the different enrichment conditions in SPME as well as the general problems of headspace analysis, a comparison with a completely different method of sample preparation is presented. Furthermore, some applications of SPME to the analysis of monoterpenes from pine needles are given.
Factors affecting the reproducibility and reliability of retention simulation in any form of temperature programmed capillary GC
Authors: Guan Yafeng , Li Linge , Zhou Liangmo 
Published: May 2005

AbstractConversion of Kováts retention indices on a given stationary phase into the thermodynamic parameters of compounds on a given column leads to a simplified method for retention simulation in isothermal, linear, and multi‐ramp temperature programmed capillary gas chromatography. The influence of numerical methods used in the computation, the temperature coefficient of Kováts indices, and the experimental factors such as isothermal temperatures selected in the measurement of n‐alkanes, column characterization and sample overloading, on the reproducibility and accuracy of simulation were discussed and examined. When the column used is properly characterized, the error between the simulated values and the experimental data is within ± 0.5 index unit or less than ± 1% of retention time.
Investigation of the solid‐ and solution‐phase binding reactivities of continuous epitopes recognized by polyclonal guinea‐pig anti‐recombinant bovine growth hormone antisera
Authors: Beattie James 
Published: May 2005

AbstractWe have used the technique of multiple pin peptide synthesis to identify three major continuous epitopes in the recombinant bovine (rb) GH molecule. We have synthesized these peptides, residues 24–40, 139–152 and 179–189, as N‐terminally acetylate, C‐terminal amides and confirmed their reactivity in a standard solid‐phase ELISA. Subsequently, for epitope 139–152, we have synthesized a peptide affinity column and used this to isolate antibodies with this epitospe specificity from whole antiserum. In addition, we demonstrate that under native conditions in a liquid phase RIA, these antibodies will precipitate [125I]rbGH. Further, peptide 139–152 itself also cross‐reacts in an rbGH RIA inhibiting binding by up to 20%. Our data suggest that during the immune response to rbGH RIA in guinea‐pigs a substantial part of the B‐cell response is directed to the 139–152 region and that this part of the protein is a native epitope.
Binding of the kunitz‐type trypsin inhibitor DE‐3 from Erythrina caffra seeds to serine proteinases: a comparative study
Authors: Onesti Silvia , Matthews David J. , Aducci Patrizia , Amiconi Gino , Bolognesi Martino , Menegatti Enea , Ascenzi Paolo 
Published: May 2005

AbstractThe effect of pH and temperature of kinetic and thermodynamic parameters (i.e.,kon,koff,Ka, δGo, δHo and δSo values) for the binding of the kunitz‐type trypsin inhibitor DE‐3 from Erythrina caffra seeds (ETI) to bovine β‐trypsin, bovine α‐chymotrypsin, the human tissue plasminogen activator, human α‐, β‐ and γ‐thrombin, as well as the Mr 33000 and Mr 54 000 species of the human urinary plasminogen activator (also named urokinase) has been investigated. At pH 8.0 and 21.0 °C: (i) values of the second‐order rate constant (Kon) for the proteinase: ETI complex formation vary between 8.7 × 105 and 1.4 × 107/M/s; (ii) values of the dissociation rate constant (koff) for the proteinase: ETI complex destabilization range from 3.7 × 10−5 to 1.4 × 104/s; and (iii) values of the association equilibrium constant (Ka) for the proteinase: ETI complexation change from < 1.0 × 104 to 3.8 × 1011/M. Thus, differences in koff values account mostly for the large changes in Ka values for ETI binding. The affinity of ETI for the serine proteinases considered can be arranged as follows: bovine β‐trypsin > human tissue plasminogen activator > bovine β‐chymotrypsin » human α‐, β‐ and γ‐thrombin ≈︁ o Mr 33 000 and Mr 54000 species of the human urinary plasminogen activator. Moreover, the serine proteinase: ETI complex formation is an endothermic, entropy‐driven, process. On increasing the pH from 5.0 to 9.0 (at 21.0 °C), the affinity of ETI for bovine β‐trypsin, the human tissue plasminogen activator and bovine α‐chymotrypsin (i.e., Ka values) increases, thus reflecting the acidic‐pK shift of the His57 catalytic residue from ≈︁≈︁ 7.0, in the free enzymes (pKUNL), to ≈︁5.2, in the serine proteinase: ETI complexes (pKLIG). The ETI‐binding properties have been analysed in parallel with those of related serine (pro)enzyme/macromolecular inhibitor systems. Considering the known molecular models, the observed binding behaviour of ETI is discussed in relationship to the inferred stereochemistry of the serine proteinase/inhibitor contact regions.
The infrared and Raman spectra of perchloro‐[4] ‐ radialene
Authors: Finseth Dennis H. , Miller Foil A. 
Published: May 2005

AbstractInfrared and Raman spectra are reported for polycrystalline perchloro‐[4]‐radialene and for solutions in CCl4 and CS2. An earlier X‐ray structure determination by van Remoortere and Boer has shown that in the crystal the molecular symmetry is almost D2d (puckered ring), but is slightly distorted to C2. This distortion was attributed to crystal packing forces. The vibrational spectrum does not show the distortion. The spectra are essentially the same for polycrystalline solid as for solution, and are completely compatible with D2d in both states. Assignments are made for a few of the modes where evidence warrants it. Some observations are also made about the mass spectrum, which has a rich structure because of the many isotopic species.
Resonance Raman spectra of Cu‐porphin‐d4(meso) and Ni‐porphin, and the infrared spectrum of Cu‐porphin‐d4
Authors: Verma A. L. , Asselin M. , Sunder S. , Bernstein H. J. 
Published: May 2005

AbstractThe resonance Raman spectra are presented for Ni‐porphin and Cu‐porphin‐d4(meso) as dilute solutions in CS2 and C2Cl4 using an Ar+ laser and a tunable Rhodamine 6G dye laser. The Raman features are assigned to the different vibrational species on the basis of their depolarization data. The assignment of 14 features in the spectrum of Cu‐porphin‐d4 and 13 features in the spectrum of Cu‐porphin and Ni‐porphin is discussed by comparing the spectra of the three molecules. Also the infrared spectrum of Cu‐porphin‐d4 as a solid dispersed in CsI matrix is reported for the 200–2000 cm−1 region.
On the value of the depolarization ratio of fundamentals of sandwich compounds with an electronically degenerate ground state
Authors: Koningstein J. A. , Aleksanyan V. T. 
Published: May 2005

AbstractThe selection rules are derived for the Raman activity of fundamental modes in electronically degenerate groundstates of sandwich compounds. Emphasis is placed on the occurrence of asymmetric tensors, which can result in values of the depolarization ratio of Raman bands larger than 3/4.
Resonance Raman spectra of p‐hydroxyazobenzene and its ring deuterated derivatives in the strongly acidic solution
Authors: Machida Katsunosuke , Lee Hohi , Saito Yutaka , Uno Toyozo 
Published: May 2005

AbstractResonance Raman spectra of p‐hydroxyazobenzene (HAB) and its three ring deuterated derivatives have been measured in the strongly acidic solution. The observed Raman bands have been assigned by referring to the spectra of related compounds and the deuteration effect. The NN stretching band of HAB in the solution of 20% hydrochloric acid undergoes a high frequency shift by about 60 cm−1 on changing the solvent to 20% deuterochloric acid. In the strongly acidic solution HAB has been confirmed to exist as a resonance hybrid between the azo and the hydrazone forms, of which the former is predominant. A normal coordinate analysis of a simplified model, CNHNC6H4pOH, has been carried out to give a good agreement between the calculated and the observed frequencies.
A computer controlled high resolution Raman spectrometer system
Authors: Fletcher William H. , Rayside John S. , McLendon William B. 
Published: May 2005

AbstractThe design and performance of a computer controlled high resolution scanning Raman spectrometer system is described. Resolution of 0.05 cm−1 has been achieved with vibration‐rotation bands with single mode laser operation. Pure rotation lines have been observed with 0.04 cm−1 slit widths.
Resonance Raman spectra of platinum ethylenediamine complexes
Authors: Papavassiliou G. C. , Theophanides T. 
Published: May 2005

AbstractThe resonance Raman spectra (RRS) of PtenX3 and the Raman spectra (RS) of PtenX2 and PtenX4, where X = Cl or Br, have been studied. The progression of the symmetric fundamental ν1,…XPt(IV)X…Pt(IV)X…of PtenX3 up to 10ν1 and the ωe and χe values have been found to be 304.1 and 0.7 cm−1, for the chloro and 175.1 and 0.4 cm−1 for the bromo derivative. The dissociation bond energies of XPt(IV) are found to be 94 and 54 Kcal, respectively.
Observation of Br2 stretch modes of adsorbed molecules on various substrates
Authors: Bernussi A. A. , Gualberto G. M. 
Published: May 2005

AbstractWe report the observation of the Raman modes of Br2 molecules bound to graphite, KBr and fused quartz substrates. The results demonstrate that Br2 bonds to surfaces at preferred sites, except in the case of fused quartz, where no unique site can be defined owing to its amorphous nature. The spectra of Br2 on the KBr substrate, taken at later times, exhibit modes that are related to a chemical modification of the KBr substrate.
Raman spectral studies at rotating pyrolytic graphite electrodes
Authors: McQuillant A. J. , Hester R. E. 
Published: May 2005

AbstractRaman spectra of highly oriented pyrolytic graphite electrodes with the basal plane exposed (BPG) and the basal plane edges exposed (EPG) have been investigated in aqueous acidic media using a rotating electrode cell. Anodic oxidation of these electrodes and subsequent reduction resulted in the original sharp band at 1581 cm−1 being replaced by a broader band at ca 1600 cm−1 with a new broad band associated with disordered carbon emerging in the 1300–1400 cm−1 region. The Raman spectrum of multilayers of thionine (3,7‐ diaminophenothiazinium chloride) electrodeposited on BPG electrodes has been recorded. The spectral sensitivity has been found to be such that monolayer detection is unlikely at this electrode.
Raman spectra of solid films 3—Mg, Cu and Zn phthalocyanine complexes
Authors: Jennings Carol , Aroca Ricardo , Hor Ah‐Mee , Loutfy R. O. 
Published: May 2005

AbstractThin solid films of Mg, Cu and Zn phthalocyanine complexes have been studied using Raman spectroscopy. Laser excitation lines near resonance and in resonance with the electronic absorption band of the substrate have been used. A description of vibrational modes is given and correlations in vibrational properties of the series are discussed.
On the theory of the dominant artefacts in natural and magnetic Raman optical activity
Authors: Barron L. D. , Vrbancich J. 
Published: May 2005

AbstractThe molecular theory of the scattering of polarized light is applied to the problem of the artefacts that frequently arise in Raman circular intensity difference measurements. By including the effect of the finite solid angle in the cone of collected light, a detailed understanding of the major sources of artefacts in polarized and depolarized measurements, and their dependence on the polarization characteristics of the Raman band, is obtained. Inclusion of both antisymmetric and symmetric scattering contributions reveals why magnetic are usually less susceptible to artefacts than natural Raman optical activity spectra.
Polaritons in complex bulk media
Authors: Anikiev A. A. , Reznik L. C. , Umarov B. S. , Scott J. F. 
Published: May 2005

AbstractTheory and experiment for phonon‐like polaritons in complicated bulk media are discussed. The media include crystals with diffusion, such as ionic conductors, in which the theoretical approaches of Merten and Borstel, Nakamura and Barker and London are compared; systems having polariton anomalies in the frequency region in which the two‐phonon density of states peaks, such as ammonium chloride and calcite; and lithium niobate with optical damage.
Raman spectra of polycrystalline SmBr3 and single crystal NdBr3
Authors: Wilmarth W. R. , Begun G. M. , Daniel J. F. , Hart R. C. , Nave S. E. , Peterson J. R. 
Published: May 2005

AbstractRaman spectra of polycrystalline NdBr3 and SmBr3 were recorded at room temperature and pressure and polarized Raman spectra of single crystal NdBr3 were also measured. Based on these polarized spectra, symmetry assignments of eight Raman‐active modes were made. The assignments are useful in interpreting the phonon Raman spectra of these and other compounds which exhibit the PuBr3‐type orthorhombic structure and in identifying this structure type quickly by Raman spectroscopy.
Raman spectra of porcine mitochondrial malate dehydrogenase
Authors: Hall William H. , Jagodzinski Paul W. 
Published: May 2005

AbstractRaman spectra of porcine mitochondrial malate dehydrogenase have been collected and analysed. The existence of weak hydrogen bonds is indicated by the intensity ratio of the tyrosine doublet and a band is found which can be attributed to disulfide bonds. The observed frequencies in the amide I and III regions favor significant contributions from α‐helix and random conformations. An analysis of the intensities using standard methods predicts a very low β‐sheet content.
Raman and infrared spectra of the solid chlorofluorocarbons. II–Dichlorodifluoromethane
Authors: Leblanc L. M. , Anderson A. 
Published: May 2005

AbstractRaman and infrared spectra of solid dichlorodifluoromethane were recorded in both the internal and lattice mode regions at temperatures between 20 and 80 K. The lattice spectra suggest that the unit cell is small and noncentrosymmetric, and a bimolecular tetragonal cell with factor group C4 is compatible with the observed results. Plausible assignments of all main spectroscopic features are presented, and splittings of internal modes are interpreted in terms of isotopic, crystal, field, Fermi resonance and LO–TO effects.
Normal coordinate analysis and vibrational assignments of 1,1,3,3‐tetramethyldisiloxane
Authors: Gnado J. , Dhamelincourt P. 
Published: May 2005

AbstractRaman and infrared spectra of liquid 1,1,3,3‐tetramethyldisiloxane were recorded in the ranges 100–3500 and 400–4000 cm−1, respectively. A normal coordinate analysis based on a generalized valence force field was carried out. Using the potential energy distributions and the atomic displacements, this investigation permitted a reasonable interpretation of the observed vibrational modes and a description of the coupling of these modes in the 100–1500 cm−1 region where the spectra exhibit a complex structure.
Vibrational spectra of the cis and trans isomers of the Mo(CO)4(PPh3)2 complex
Authors: Shamir J. , Givan A. , Ardon M. , Ashkenazi G. 
Published: May 2005

AbstractRaman and infrared spectra of polycrystalline cis and trans isomers of the Mo(CO)4(PPh3)2 complex were recorded at room temperature. The molecular vibrations around the central Mo atoms and the carbonyl ones were assigned and correlated with the group theoretical treatment. Some changes in the spectra of the triphenylphosphine ligand have also been discussed.
Raman spectra, absolute Raman intensities and electro‐optical parameters of pertechnetate, perrhenate and periodate ions in aqueous solution
Authors: Eysel Hans H. , Kanellakopulos Basil 
Published: May 2005

AbstractComplete Raman spectra of all four fundamentals of pertechnetate, perrhenate and periodate ions in aqueous solution were measured and calibrated against NaClO4, as an external standard. Electro‐optical parameters for the TcO, ReO and IO bonds were calculated. Changes in the previously published force fields were necessary to adjust the eigenvectors to the experimental frequencies and intensities in an aqueous environment. Equilibrium bond polarizabilities were estimated from refractive index measurements in connection with Raman intensities of the v2 bending modes. The results are discussed in connection with the ionic size of the XO4− anions and behaviour of perrhenate and pertechnetate ions in extraction processes.
The transformation of τ‐particles into T4 heads. I. Evidence for the conservative mode of this transformation.
Authors: Bijlenga R. K. L. , v. d. Broek R. , Kellenberger E. 
Published: May 2005

AbstractAsynchroneous T4 phage head maturation includes the step of P23 cleavage: P23 of head‐related τ‐particles is cleaved into P23This paper is part of the thesis of R. K. L. Bijlenga. It is number X of the series: “Studies on the morphopoieses of the head of phage T‐even.”
of capsids with a conservative mode of transformation as evidenced by “heavy” labeling in temperature shift‐down experiments with mutant 24 (tsL90). Assuming a subunit pool, data indicate in situ cleavage on individual precursor particles. The interpretation becomes less interesting when assuming a compartmentation of the membrane surface; this hypothesis is not ruled out.
Recombination of human erythrocyte apoprotein and lipid. I. Interaction of apoprotein and lipid at the air‐water interface
Authors: Morse Philip D. 
Published: May 2005

AbstractThe formation and stabilization of a complex between total erythrocyte apoprotein and monolayers of total erythrocyte lipid as measured by changes of surface pressure (Δπ) and rate of change of surface pressure (dπ/dt) was studied as a function of pH, ionic strength, and lipid surface pressure. Penetration of apoprotein into lipid monolayers was favored by conditions in which lipid and apoprotein were oppositely charged. Once the interaction was completed, the resultant surface complex was resistant to large changes in subphase pH and ionic strength as shown by the insensitivity of Δπ to these parameters. The dπ/dt, however, showed strong dependence on pH and ionic strength, but not on lipid surface pressure. A sharp decrease in dπ/dt around pH 3.5–4.5 is associated with the change in apoprotein charge from (+) to (−). Comparison of complex formation between apoprotein and bovine serum albumin, cytochrome c, and human hemoglobin suggests that erythrocyte apoprotein was specialized in its interaction with erythrocyte lipids. The data show that formation of an apoprotein‐lipid complex at the air‐water interface has both electrostatic and hydrophobic components. This contradicts results from other laboratories studying erythrocyte membrane recombination by bulk methods.
Recombination of human erythrocyte apoprotein and lipid. II. Visualization of apoprotein‐lipid bilayer complex by freeze‐etching
Authors: Wehrli Ernst , Morse Philip D. 
Published: May 2005

AbstractBilayers of human erythrocyte apoprotein‐lipid complexes were made by dipping a mica plate through monolayers of the complex formed at the air‐water interface. Stearic acid and erythrocyte lipid alone served as controls. Freeze‐fracture images of the complex at high lipid surface pressures (30 dynes/cm) showed particles (average diameter, 109 Å ± 18 Å) similar to those of erythrocyte ghosts (average diameter, 102 Å ± 19 Å). Control surfaces were smooth. We conclude that part or all of the protein molecule penetrated into the lipid bilayer and that erythrocyte apoprotein‐lipid complexes yield fracture faces similar to the native erythrocyte membrane.