University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Vibrational Spectroscopy

  • Publisher: Elsevier
  • FAD Code: VIBS
  • CODEN: VISPEK
  • ISSN: 0924-2031
  • Abbreviation: Vib. Spectrosc.
  • DOI Prefix: 10.1016/j.vibspec,10.1016/S0924-2031
  • Language: English
  • Comments: Fulltext from 1990 V1

Citations 11

"Raman, IR, And Surface-enhanced Raman Spectroscopy Of Papaverine: An Automated Setup For In Situ Synthesis Of The Silver Substrate And Recording Of The SER Spectra"
Vib. Spectrosc. 2004 Volume 36, Issue 1 Pages 47-55
N. Leopold, J. R. Baena, M. Bolboac, O. Cozar, W. Kiefer and B. Lendl

Abstract: Raman, IR, and surface-enhanced Raman scattering (SERS) were employed for the vibrational characterization of papaverine in the free and adsorbed state. The vibrational assignments were performed by means of density functional theory (DFT) calculations. The adsorption of the molecule was concluded with the isoquinoline and the benzene ring close to the silver surface in tilted orientations. Employing a sequential injection system, an automatized setup was developed for reliable, accurate and rapid recording of FT-SER spectra. The colloidal silver substrate was synthesized in situ in a 2 mL quartz cuvette by reducing silver nitrate with hydroxylamine. The FT-SER spectrum of papaverine obtained with the developed experimental setup exhibits the same characteristics as the SER spectrum obtained with a citrate reduced silver colloid.

"Assessment Of Quantum Cascade Lasers As Mid Infrared Light Sources For Measurement Of Aqueous Samples"
Vib. Spectrosc. 2002 Volume 29, Issue 1-2 Pages 283-289
Malin Kölhed, Michael Haberkorn, Viktor Pustogov, Boris Mizaikoff, Johannes Frank, Bo Karlberg and Bernhard Lendl

Abstract: The potential of Fabry Perot Quantum Cascade (QC) lasers for transmission measurements of aqueous samples was assessed. For this purpose two lasers, one lasing in the region of the bending vibration of water at 1650 cm-1, and the other in the water window at 1080 cm-1, were used in a flow injection system comprising a dedicated fiber-optic flow cell with an adjustable path length. As test analytes a nucleic base (adenine) and a nucleoside (xanthosine) were used. Compound-specific information was obtained as the nucleoside contained a carbohydrate unit in addition to the heteroaromatic ring structure. With the laser emitting at 1650 cm-1 the heteroaromatic ring structure of both compounds gave rise to flow injection peaks, whereas, only the nucleoside, containing the C-O stretching vibrations of the carbohydrate unit, produced peaks also with the laser emitting at 1080 cm-1. The path length limitations were investigated for both lasers. For the 1650 cm-1 laser, path lengths up to 59 mum could be used, despite the strong absorption of water. For xanthosine analysis, the limit of detection (S/N = 3) at this path length was determined to be 0.07 g L-1. Optical path lengths of up to 150 mum could be used for the laser emitting at 1080 cm-1. (C) 2002 Elsevier Science B.V. All rights reserved.

"Attenuated Total Internal Reflection Infrared Microspectroscopy For The Analysis Of Trace Solutes In Aqueous Solutions"
Vib. Spectrosc. 2000 Volume 24, Issue 1 Pages 93-100
André J. Sommer and Mark Hardgrove

Abstract: A method for the study of solutes in aqueous solutions using a micro-attenuated total internal reflection (ATR) accessory with microscopic condensation was investigated The accessory employs a single bounce internal reflection element (IRE, Si or Ge) which focuses the infrared radiation to a 10 pL volume element. By microscopic condensation of the analyte into this volume element, detection limits in the parts per million regime were observed for polyethylene glycol (PEG) and polyacrylic acid (PAA), The method was found to be linear over several orders of magnitude and could be implemented on a standard Fourier transform infrared spectrometer, Techniques to improve the method by placing a hydrophobic annulus on the IRE and the use of the device as an HPLC detector are discussed.

"Flow Injection Fourier Transform Infrared Determination Of Caffeine In Coffee"
Vib. Spectrosc. 1999 Volume 21, Issue 1-2 Pages 143-150
Zouhair Bouhsain, Jose M. Garrigues, Salvador Garrigues and Miguel de la Guardia

Abstract: A fully automatized procedure has been developed for the Fourier transform infrared (FT-IR) spectroscopic determination of caffeine in coffee samples. The method involves the online extraction of caffeine with CHCl3. Samples, weighed inside empty PTFE cartridges of 0.5 cm internal diameter (i.d.) and 1.5 mL volume, were humidified with four drops of 0.25 M NH3. The cartridge was installed in a flow manifold, in which samples were extracted in a closed-flow system with 1 mL CHCl3, during 6 min. Four hundred microliters of the extract were introduced in a microflow cell and absorbance measured as a function of time at 1659 cm-1, with a baseline established between 1900 and 830 cm-1, thus providing a fiagram. Peak height values of the Fl recordings, obtained for samples, were interpolated in an external calibration line established from standard solutions of caffeine in CHCl3,. The method provided a limit of detection (LOD) of 9 mg L-1 caffeine, a relative standard deviation of 0.6% for five independent measurements of a solution containing 1 mg mL-1 and a sampling frequency of the whole procedure of 6 h-1. Results obtained for market samples agree well with those found by the official chromatographic-spectrometric method, but involving a drastic reduction of solvents, from the 200 mL ether and 50 mL CHCl3, required for each sample preparation by the reference procedure to less than 30 mL CHCl3, necessaries for the whole determination of caffeine in a sample, also including standards and carrier solution.
Caffeine Coffee Spectrophotometry Interface Optimization Method comparison

"Flow-through Sensors For Enhancing Sensitivity And Selectivity Of FTIR Spectroscopy In Aqueous Media"
Vib. Spectrosc. 1999 Volume 19, Issue 1 Pages 1-10
B. Lendl and R. Schindler

Abstract: The principle of novel flow-through sensor systems with FTIR spectroscopic detection is presented on the example of the determination of organic acids in aqueous solution. The constructed flow-through sensor system is based on trapping of derivatized porous polymer beads in a conventional IR transmission cell and integration of the flow cell into a sequential injection (SI) manifold. By the SI-manifold sample pre-conditioning, sample-sensor interaction and sensor regeneration were performed in an automated and highly reproducible way. The polymer beads used in this study contained anion exchanger groups so that negatively charged molecules such as organic acids present in the anionic form could selectively interact with the polymer beads. Upon pumping a sample through the sensor cell organic acids were retained on the polymer beads whereas non-ionic matrix molecules passed hence allowing to separate the target analytes form the matrix. Apart from that the organic acids were also concentrated onto the polymer beads so that absolute analyte amounts in the low µg range could easily be detected. Linear calibration curves from 0 to 1 mmol L-1 were recorded for acetic and malic acid using a sample volume of 500 µl (s(x0): 0.032 mmol L-1 acetic acid and 0.031 mmol L-1 malic acid). Mixtures of both acids were analyzed as well and it could be shown that by application of multivariate data evaluation procedures (PLS) simultaneous quantification of both acids could be performed successfully using the developed flow-through sensor system.

"Determination Of Enzyme Kinetics And Chemometric Evaluation Of Reaction Products By FTIR Spectroscopy On The Example Of β-fructofuranosidase"
Vib. Spectrosc. 1998 Volume 16, Issue 2 Pages 127-135
R. Schindler, H. Le Thanh, B. Lendl* and R. Kellner

Abstract: FTIR spectroscopy in combination with a sequential injection analysis (SIA) manifold was used for the investigation of the kinetic properties of the quant. anal. of the reaction mixtures of β-fructofuranosidase. Different sucrose solutions were prepared automatically and with the quant. results provided by the chemometric spectra evaluation, the Km was estimated to be 43 mM.
Enzyme, β-fructofuranosidase Spectrophotometry Sequential injection Chemometrics Kinetic

"Determination Of Carbonates In Waters By Online Vapor Generation FTIR"
Vib. Spectrosc. 1998 Volume 16, Issue 1 Pages 61-67
A. Pérez-Ponce, S. Garrigues and M. de la Guardia*

Abstract: An electrically heated gas-permeation unit (GPU) has been employed for the vapor-generation Fourier transform infrared (FTIR) determination of total carbonate in waters. The developed method is based on the simultaneous injection of 100 l sample and 100 l nitric acid in a two-channel manifold with a merging zone, which provides the generation of CO2 through the GPU, heated at 90°C, from which CO2 is swept by a stream of N2 to a long-path infrared gas cell. Absorbance measurements were made in the range from 2500 to 2150 cm?1 and the corresponding flow injection recordings were obtained as a function of time. The areas of these peaks are interpolated in a calibration equation obtained from aqueous standards of Na2CO3 treated in the same way as samples. The method provides a limit of detection of 4.6 ppm (expressed as mg of HCO3? L-1) and a sampling frequency of 30 h?1. Results obtained for a series of natural waters compare well with those obtained by a titrimetric reference method.
Carbonate Water Spectrophotometry Volatile generation Gas phase detection

"Flow Injection Analysis With Fourier Transform Infrared Spectrometric Detection - A Potential Tool For The Analysis In Complex Matrices"
Vib. Spectrosc. 1993 Volume 5, Issue 1 Pages 33-42
E. Rosenberg and R. Kellner*

Abstract: The combination of flow-injection analysis (FIA) with FT-IR spectrometry as detector is discussed for the determination of glucose in aqueous samples. Time-domain and frequency-domain signal processing are compared and frequency-domain signal processing is found to give superior qualitative and quantitative information. With frequency-domain signal processing, the enzymatic degradation of glucose can be used for its measurement. This method is shown to be successfully applicable in the physiologically interesting concentration range (50-500 mg dL-1). For the quantitative measurement, the difference signal of the sample before and after the reaction is evaluated. Although this approach should theoretically render the method insensitive towards other sample constituents, even with glucose-fructose mixtures severe interferences exist. A possible explanation is the influence on the background spectrum by the pH shift occurring during the reaction.
Spectrophotometry Review

"Identification Of Stimulant Drugs By Surface-enhanced Raman Spectrometry On Colloidal Silver"
Vib. Spectrosc. 1991 Volume 2, Issue 2-3 Pages 145-154
A. Rupérez, R. Montes and J. J. Laserna*

Abstract: The surface-enhanced Raman (SER) spectra of stimulant drugs, including mefenorex, pentylenetetrazole, -amphetamine and pemoline, were obtained on colloidal silver. Silver colloids are prepared in a single step, at room temperature, by chemical reduction of Ag+ with sodium tetrahydroborate. Spectra are recorded using drug concentrations at the g mL-1 level. Individual drugs can be identified by characteristic vibrational bands. The SER spectrum of human urine and that of human urine spiked with mixtures of stimulant drugs are reported.
Drugs LC Electrode Raman

"Enhancement Of Fourier Transform Infrared Spectrometry By The Flow Injection Technique: Transmittance And Internal Total Reflectance Cell In A Single-line System"
Vib. Spectrosc. 1991 Volume 2, Issue 1 Pages 1-14
M. Guzman, J. Ruzicka and G. D. Christian, P. Shelley

Abstract: A study was made of the ability of a flow injection analysis (FIA) system to undertake automated dilutions when coupled to an FTIR spectrometer, and to carry out multi-component determinations. A transmittance cell and a cylindrical internal total reflectance (Circle) cell were compared. Ternary mixtures containing 1 to 2% acetone, ethanol and THF in CCl4 were analyzed using the transmittance cell. A stopped-flow method was used with the Circle cell in order to enhance the signal-to-noise ratio, and ternary mixtures with 7 to 60% acetone, 3 to 20% ethanol and 1 to 20% THF in CCl4 were used. The determinations were performed using a multivariate calibration method (partial least squares).
Spectrophotometry CIRCLE cell Dilution Signal to noise ratio Stopped-flow Multivariate calibration Partial least squares

"Selective Measurement Of Resonance Raman And Absorption-spectra Of Different Charged Species Produced In The Electrooxidation Of N,N'-Dimethyl-N,N'-Diphenylbenzidine By Means Of A Column Electrolytic Continuous-flow Method"
Vib. Spectrosc. 1991 Volume 1, Issue 4 Pages 329-338
Munetaka Oyama and Satoshi Okazaki*, Toshihiko Nagamura

Abstract: A novel multi-functional flow-electrolysis spectrochemical measurement system was developed for electrochemical and spectrophotometric analyzes of electrogenerated species in homogeneous solution. Both resonance Raman (RR) spectra and absorption spectra of electrolysed solutions were measured using continuous-flow controlled-potential electrolysis with a carbon-fiber column electrode, in which the quantitative electrolysis could be achieved instantaneously. The RR measurement became very easy with the help of the electrolysis current vs. potential curve at the column electrode and the absorption spectra obtained with the same solution. Decomposition and thermal absorption of the sample species could be avoided in the continuous-flow method. N,N'-Dimethyl-N,N'-diphenylbenzidine (MPB) cation radical (MPB+⋅) and dication (MPB2+) were produced selectively by the electrooxidation of MPB in acetonitrile. The RR and absorption spectra of electrolysed solution of MPB were observed under different electrolysis conditions. The dependence of the absorption spectra on the applied potential revealed that MPB+⋅ and MPB2+ had absorption maxima at 476 and 512 nm, respectively. With excitation by an argon ion laser, the RR spectra of MPB+⋅ and MPB2+ were observed selectively using an image-intensified multi-channel photodiode-array detector. The present system can be applied to time-resolved RR measurements with a minimum gate time of 25 ms.
Raman Column