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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 367 (2000), S. 211-214 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at λ = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 × 10–6 mol/L for ethyl xanthate, 1.3 × 10–6 mol/L for metham and 2.1 × 10–6 mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Physics, Section A 451 (1986), S. 471-480 
    ISSN: 0375-9474
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 795-797 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Natural iron concentrations in real water samples have been determined by thermal lensing as a high performance capillary electrophoresis detector. 1,10-Phenanthroline was used as a chromogenic reagent, which forms a stable complex with Fe(II) but not with Fe (III). The interferences by other cations can be neglected by a combination of this photometric technique with high performance capillary electrophoresis. Laser induced thermal lens spectroscopy is demonstrated as a new technique for the measurement of small absorbances in the picoliter detection volume of a capillary. A limit of detection of 36 nmol/L with a signal to noise ratio of 7 : 1 was achieved using a 75 μm fused silica capillary.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 788-791 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photothermal beam deflection (PBD) is a suitable method for three-dimensional, non-contact and non-destructive surface analysis. This method has been applied to the characterization of the thermal properties of natural and artificial patina and to the measurement of the thickness of the patina layers. The thickness of the outdoor and indoor patina of the roof of the Vienna Hofburg was measured to be about 22 μm and 10 μm, respectively. The thermal diffusivities of antlerite and chalcanthite were determined to 0.13 cm2/s and 0.04 cm2/s, respectively.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: 21.10.F ; 21.60 ; 27.90 ; 29.90 ; 31.30.G ; 32.50.F ; 32.80.K ; 35.10.F ; 35.80 ; 42.60.K
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Isotope shifts and hyperfine splittings in optical transitions for atomic ions of the thorium isotopes227Th to230Th and232Th have been measured by laser spectroscopy on stored ions. From the isotope shift data, changes of the mean square charge radii are determined. A continuous increase of the charge radius with mass numberA is observed, in agreement with droplet model calculations. The results indicate that the odd-even staggering for Th is different from that one of the neighbouring isotones of Fr and Ra. There is some empirical evidence from systematics for an inversion of the staggering and the appearance of an octupole deformation atN ≦137. The hyperfine splitting for229Th for 3 electronic levels is given.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 338 (1990), S. 695-698 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A crossed-beam photothermal deflection spectrophotometer (PDS) instrument was built, evaluated and applied to the determination of lanthanide neodymium. A dye laser filled with rhodamine 6 G and pumped by an argon ion laser at 514 nm was operated with outputs between 4 and 500 mW at the cuvette position and chopped at 2 Hz. The deflection of a He-Ne probe laser beam, crossing the exciting dye laser, was measured by a two-dimensional position sensitive device and two lock-in amplifiers. The setup was evaluated with a solid carbon sample and the liquids toluene and Nd3+/HClO4. A calibration curve for Nd3+ in HClO4 was obtained and the limit of detection (LOD) for Nd3+ was determined to be 2·10−6 mol/l. This LOD is, on the one hand, by 2 orders of magnitudes lower than the value obtained with the Cary 2400 spectrophotometer and, on the other hand, this transverse PDS technique is highly competitive to collinear thermal lensing and laser-induced photoacoustic spectroscopy.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 343 (1992), S. 513-517 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fiber optic modified photothermal deflection spectrometer (PTDS) was developed and tested for trace analysis of pesticides in water. A UV argon laser beam (λ=363.8 nm) was delivered to a sample cuvette either directly, or through a multimode optical fiber of 400 μm core diameter. The HeNe-probe laser beam was guided to the same sample cuvette by a monomode optical fiber of 5 μm core diameter and focussed not only transverse within an angle of 90°, but also collinear within an angle of approximately 0° to the Ar+-excitation beam. In transverse dual beam experiments a limit of detection (LOD) of 400 ppt for the pesticide DNOC (4,6-dinitroorthocresol) was achieved. The LODs for 2,4-dinitrophenol, dinoseb and dinosebacetate were 2 ppb, 18 pbb and 6 ppb, respectively. These LODs obtained with the transverse PTDS are up to 2 orders of magnitudes lower than the values taken with the Cary 2400 spectrophotometer. In collinear PTDS experiments with the pesticide dinosebacetate the enhancement factor of the LOD is about 4, when compared to the transverse PTDS using 1×1 cm2 diameter sample cuvettes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 533-535 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The limit of detection for the 4,6 dinitro-orthocresol (DNOC) pesticide, including small latex particles as light scattering samples in water as suspending medium, has been determined for the transversal photothermal deflection technique. The results where compared to conventional spectrophotometry. In the photothermal deflection experiments performed with a continuous Ar+-excitation beam (λ=363.8 nm) a LOD of 0.8 μg/l is achieved for the DNOC in water.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 354 (1996), S. 900-902 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new procedure including high performance liquid chromatography in combination with photothermal interference spectroscopy as detection device (HPLC/PIS) has been proposed, optimized and its figures of merit for pesticide residue analysis are shown. The flowing sample under study is set in one arm of a Mach-Zehnder interferometer, and its refractive index is modulated by a periodically chopped continuous wave argon ion laser. As chopper, an acousto optical modulator has been introduced to switch the excitation laser beam between different lines (457 nm, 488 nm, 514 nm) simultaneously. Thus a multi component analysis can be realized either by using an HPLC-system in front of the PIS device or by a multi line Ar+-laser, directly. The limit of detection of the HPLC/PIS system reached 71 μg/l of the pesticide di-nitro-ortho-cresol (DNOC).
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 338 (1990), S. 259-264 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Laser induced photoacoustic spectroscopy (LIPAS) has been confirmed as an analytical tool, suitable for the determination of inorganic and organic species in aqueous and organic solvents, reaching detection limits two orders of magnitude lower than those obtained with conventional spectrophotometry. A significant influence of the solvent on the enhancement of the magnitude of the LIPAS response waveform of the piezoelectric detector has been found experimentally for inorganic species (neodymium ions) and organic compounds (e.g. β-carotene and the cytochrome c), when water was replaced by organic solvents. This is particularly true, when a laser excitation wavelength above 500 nm was used, where the absorption coefficient for H2O increases drastically. Furthermore, the temperature dependence of the magnitude of the LIPAS signal has been measured, in the range between 20–70°C in samples containing Nd3+,β-carotene and the macromolecule cytochrome c in various aqueous and organic (polar and non-polar) solvents (H2O, HClO4, acetone, ethanol and petrol ether). A very strong enhancement of the LIPAS response was observed with increasing temperature (a factor of two in an interval between 20 and 40°C) for all inorganic and organic substances in aqueous solution. On the other hand, in polar and non-polar organic solvents only a slight decline of the signals of about 20% was found over the same temperature range.
    Type of Medium: Electronic Resource
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