D. Wiederin - Academia.edu (original) (raw)
Papers by D. Wiederin
Fresenius' Journal of Analytical Chemistry, 1999
A single collector double focusing sector field ICP-MS is evaluated for the determination of isot... more A single collector double focusing sector field ICP-MS is evaluated for the determination of isotope ratios. Spectral interferences (e.g. 40 Ar 23 Na on 63 Cu) can lead to calculation of inaccurate ratios. The use of high resolution enables such interferences to be separated from the isotopes of interest. External reproducibilities of < 0.02% are shown for uninterfered isotopes (measured at low resolution R = 300) and < 0.1% for interfered isotopes which required the use of medium (R = 4000) and high resolution (R = 10000).
Analytical Chemistry, 2003
Capillary electrophoresis (CE) and resonance Raman spectroscopy (RRS) with excitation in the deep... more Capillary electrophoresis (CE) and resonance Raman spectroscopy (RRS) with excitation in the deep ultraviolet (UV) region (λ ex : 244 or 257 nm) were coupled on-line. The potential of this hyphenated technique, denoted as CE-UV-RRS, for analyte confirmation/identification purposes was explored with aromatic sulfonic acids and nucleotides as test compounds. Good-quality UV-RRS spectra could be recorded on-the-fly. Identification limits for the nucleotides were in the 10-125 µg/mL range. The RRS spectra showed sufficient characteristic features to enable analyte confirmation. In addition, the identification power of UV-RRS was studied with substituted pyrenes as model compounds. The compounds were distinguishable on the basis of their RRS spectra at 244 nm. Capillary electrophoresis (CE), a powerful analytical technique with high separation efficiency, is usually combined with a UV absorption detector. However, for analyte identification purposes, it is necessary to couple CE with spectroscopic detection techniques. To date, emphasis is on the coupling with mass spectrometry (MS), which is rapidly becoming a mature technique. The possibility to couple CE with identification techniques which provide information complementary to MS, such as nuclear magnetic resonance (NMR), fluorescence line-narrowing spectroscopy (FLNS), Fourier transform infrared (FTIR) or Raman spectroscopy, (RS) would be welcome. A review covering the stateof-the-art was published a few years ago. 1 Regarding the hyphenation of CE and the vibrational techniques, FLNS, FT-IR and RS, there are various problems that hamper its realization. FLNS requires freezing of the separation to 4 K and is only applicable to fluorescent compounds. 2 Because of the IR absorption of both the fused-silica capillary and the aqueous solutions that are typically used in CE, the direct coupling with FTIR is not straightforward; nonetheless, both on-line 3 and at-line 4 combinations were recently reported. On-line CE-RS looks more promising in this respect; however, because of the lack of
Determination of the rare earth elements is important in the study of sedimentary processes. Geol... more Determination of the rare earth elements is important in the study of sedimentary processes. Geological and environmental samples often contain very low levels of these elements, and detection by plasma spectroscopy (ICP-AES, ICP-MS) is difficult unless a preconcentration and/or matrix elimination procedure is performed prior to analysis.; An automated batch preconcentration/matrix elimination system offers rapid, off-line sample preparation for a variety of sample types. A chelating form of a solid suspended reagent is added to a pH-adjusted sample. The suspended reagent with any bound elements are trapped in a hollow fiber membrane filter while unbound matrix components are washed to waste. The reagent with bound analytes are then released in a small volume. The system works in concert with an autosampler for unattended operation. Application to a variety of geological and environmental samples will be described.
Journal of Analytical Atomic Spectrometry
Elimination of arsenic species interconversion in urine via a syringe driven, inline dilution, li... more Elimination of arsenic species interconversion in urine via a syringe driven, inline dilution, liquid chromatography system.
AIP Conference Proceedings
ABSTRACT An initial study of on-line remote system for monitoring of trace metals using the induc... more ABSTRACT An initial study of on-line remote system for monitoring of trace metals using the inductively coupled plasma mass spectrometer equipped with dynamic reaction cell system is described. The three types of cleaning solutions (HF, SC-1 and SC-2) used in the traditional RCA clean procedure are analyzed periodically with one set of simple calibration curves to simulate the on-line monitoring. A remote sampling system for on-line monitoring with the combination of the ICP-MS is also demonstrated.
Analytica Chimica Acta, Oct 1, 1991
Anal Biochem, 2000
Proteins are extracted from liver into aqueous buffer at pH 7 and separated by size exclusion chr... more Proteins are extracted from liver into aqueous buffer at pH 7 and separated by size exclusion chromatography (SEC). Inductively coupled plasma mass spectrometry (ICP-MS) with a magnetic sector mass spectrometer is used to identify those protein fractions that contain Cu, Zn, Mn, Fe, Cd, S, P, Mo, Co, Ca, or Mg. The experimental setup provides very high sensitivity. Measurements at medium spectral resolution remove polyatomic interferences for some difficult elements like Fe, S, and P. Some elements are found in different molecular weight proteins; for example, cadmium binds to four different protein fractions (>400 kDa, 70 kDa, and metallothionein). Other elements like Mo, Ca, and Mg are present only in low-molecular-weight proteins or other small molecules.
Fresenius' Journal of Analytical Chemistry, 1999
A single collector double focusing sector field ICP-MS is evaluated for the determination of isot... more A single collector double focusing sector field ICP-MS is evaluated for the determination of isotope ratios. Spectral interferences (e.g. 40 Ar 23 Na on 63 Cu) can lead to calculation of inaccurate ratios. The use of high resolution enables such interferences to be separated from the isotopes of interest. External reproducibilities of < 0.02% are shown for uninterfered isotopes (measured at low resolution R = 300) and < 0.1% for interfered isotopes which required the use of medium (R = 4000) and high resolution (R = 10000).
Analytical Chemistry, 2003
Capillary electrophoresis (CE) and resonance Raman spectroscopy (RRS) with excitation in the deep... more Capillary electrophoresis (CE) and resonance Raman spectroscopy (RRS) with excitation in the deep ultraviolet (UV) region (λ ex : 244 or 257 nm) were coupled on-line. The potential of this hyphenated technique, denoted as CE-UV-RRS, for analyte confirmation/identification purposes was explored with aromatic sulfonic acids and nucleotides as test compounds. Good-quality UV-RRS spectra could be recorded on-the-fly. Identification limits for the nucleotides were in the 10-125 µg/mL range. The RRS spectra showed sufficient characteristic features to enable analyte confirmation. In addition, the identification power of UV-RRS was studied with substituted pyrenes as model compounds. The compounds were distinguishable on the basis of their RRS spectra at 244 nm. Capillary electrophoresis (CE), a powerful analytical technique with high separation efficiency, is usually combined with a UV absorption detector. However, for analyte identification purposes, it is necessary to couple CE with spectroscopic detection techniques. To date, emphasis is on the coupling with mass spectrometry (MS), which is rapidly becoming a mature technique. The possibility to couple CE with identification techniques which provide information complementary to MS, such as nuclear magnetic resonance (NMR), fluorescence line-narrowing spectroscopy (FLNS), Fourier transform infrared (FTIR) or Raman spectroscopy, (RS) would be welcome. A review covering the stateof-the-art was published a few years ago. 1 Regarding the hyphenation of CE and the vibrational techniques, FLNS, FT-IR and RS, there are various problems that hamper its realization. FLNS requires freezing of the separation to 4 K and is only applicable to fluorescent compounds. 2 Because of the IR absorption of both the fused-silica capillary and the aqueous solutions that are typically used in CE, the direct coupling with FTIR is not straightforward; nonetheless, both on-line 3 and at-line 4 combinations were recently reported. On-line CE-RS looks more promising in this respect; however, because of the lack of
Determination of the rare earth elements is important in the study of sedimentary processes. Geol... more Determination of the rare earth elements is important in the study of sedimentary processes. Geological and environmental samples often contain very low levels of these elements, and detection by plasma spectroscopy (ICP-AES, ICP-MS) is difficult unless a preconcentration and/or matrix elimination procedure is performed prior to analysis.; An automated batch preconcentration/matrix elimination system offers rapid, off-line sample preparation for a variety of sample types. A chelating form of a solid suspended reagent is added to a pH-adjusted sample. The suspended reagent with any bound elements are trapped in a hollow fiber membrane filter while unbound matrix components are washed to waste. The reagent with bound analytes are then released in a small volume. The system works in concert with an autosampler for unattended operation. Application to a variety of geological and environmental samples will be described.
Journal of Analytical Atomic Spectrometry
Elimination of arsenic species interconversion in urine via a syringe driven, inline dilution, li... more Elimination of arsenic species interconversion in urine via a syringe driven, inline dilution, liquid chromatography system.
AIP Conference Proceedings
ABSTRACT An initial study of on-line remote system for monitoring of trace metals using the induc... more ABSTRACT An initial study of on-line remote system for monitoring of trace metals using the inductively coupled plasma mass spectrometer equipped with dynamic reaction cell system is described. The three types of cleaning solutions (HF, SC-1 and SC-2) used in the traditional RCA clean procedure are analyzed periodically with one set of simple calibration curves to simulate the on-line monitoring. A remote sampling system for on-line monitoring with the combination of the ICP-MS is also demonstrated.
Analytica Chimica Acta, Oct 1, 1991
Anal Biochem, 2000
Proteins are extracted from liver into aqueous buffer at pH 7 and separated by size exclusion chr... more Proteins are extracted from liver into aqueous buffer at pH 7 and separated by size exclusion chromatography (SEC). Inductively coupled plasma mass spectrometry (ICP-MS) with a magnetic sector mass spectrometer is used to identify those protein fractions that contain Cu, Zn, Mn, Fe, Cd, S, P, Mo, Co, Ca, or Mg. The experimental setup provides very high sensitivity. Measurements at medium spectral resolution remove polyatomic interferences for some difficult elements like Fe, S, and P. Some elements are found in different molecular weight proteins; for example, cadmium binds to four different protein fractions (>400 kDa, 70 kDa, and metallothionein). Other elements like Mo, Ca, and Mg are present only in low-molecular-weight proteins or other small molecules.