bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Formation Constant of the Copper Chelate of β-Cyclodextrin by Spectrophotometric Titration with Ethylenediaminetetraacetic Acid Using Window Factor Analysis
Authors: Darj Mike , Malinowski Edmund R.
Published: October 2003

Copper(II) is known to form a 2:1 complex with β-cyclodextrin in alkaline solution (pH ≥ 12), but its formation constant has not been determined. The present investigation involves the determination of the formation constant of the complex by spectrophotometric titration with ethylenediaminetetraacetic acid (EDTA) using window factor analysis (WFA). WFA is a self-modeling chemometric technique that extracts the concentration profiles of individual species from evolutionary processes such as complexometric titration. The visible absorption spectra of eleven aqueous solutions, at pH 12, containing fixed amounts of copper and cyclodextrin and different amounts of EDTA, were recorded. Principal factor analysis (PFA) of the absorbances gave evidence that three components were responsible for the spectral data. The concentration profiles of the components formed were extracted by WFA. Applying stoichiometric balance to the concentration profiles, the titration complex was determined to be (Cu2HO2CD·EDTA)−7, and the logarithm of its formation constant was calculated to be 8.51 ± 0.21. Using this information and the solubility product constant of Cu(OH)2 as well as the formation constant of (CuOH·EDTA)−3, the logarithm of formation constant of (Cu2HO2CD)−3 was detemined to be 35.78 ± 0.38.
Spectrally Resolved Fluorescence Lifetime Imaging Microscopy
Authors: Hanley Quentin S. , Arndt-Jovin Donna J. , Jovin Thomas M.
Published: October 2003

We report a system for collecting spectrally resolved fluorescent lifetime images. Frequency domain fluorescence lifetime detection was combined with two-dimensional spectral imaging in a programmable array microscope. The spectroscopic fluorescence lifetime imaging microscopy (sFLIM) system has a resolution of ∼50 (λ/Δλ) in the current arrangement and a wavelength range of ∼430–750 nm. With the sFLIM system, we recorded the lifetime spectra of rhodamine 6G, rhodamine B, and the DNA intercalation dye propidium iodide (PI) in cuvettes and an EGFP-fusion of the histone 2A variant D protein in Drosophila salivary gland explants in the presence and absence of PI. In the absence of PI, the EGFP-fusion exhibited a lifetime of 2.7 ns with little variation in wavelength. The lifetime of PI alone ranged from ∼1 ns in buffer to ∼18 ns when intercalated in the nuclei of intact cells. The combination of EGFP and PI in the Drosophila salivary gland explants exhibited strong fluorescence resonance energy transfer (FRET), a result consistent with the known nucleosomal structure of eukaryotic chromatin.
Temperature Dependence of Fluorescent Probes for Applications to Polymer Materials Processing
Authors: Bur Anthony J. , Vangel Mark G. , Roth Steven
Published: October 2003

We have examined the temperature dependence of fluorescence spectra from dyes that can be used as molecular probes during polymer processing. The dyes, perylene and benzoxazolyl stilbene, are in a class of dyes called band definition dyes, so called because their fluorescence spectra contain distinct intensity peaks at characteristic wavelengths. The dyes were chosen for this study because they are soluble at dopant levels of concentration in organic polymers at elevated temperatures and they survive without degradation at polymer processing temperatures up to 300 °C. Changes induced in the fluorescence spectra over a range of typical processing temperatures were examined using statistical techniques that establish correlations between fluorescence intensity, wavelength, and temperature. The derived correlations are the basis for temperature calibrations that can be applied to process monitoring. A phenomenological model that assumes temperature dependence for both nonradiative and radiative decay modes is developed. A fit of the model parameters to the fluorescence spectra yielded activation energies for the temperature dependence of fluorescence decay rates.
Bone Tissue Fluorescence Reduction for Visible Laser Raman Spectroscopy
Authors: Shea Dana A. , Morris Michael D.
Published: October 2003

We report the successful reduction of background fluorescence in bone tissue by photo-irradiation with green laser light. Irradiation of bone tissue with intense green light has been shown to be nondestructive and to reduce permanently over 70% of the fluorescence background. The laser power dependence of the fluorescence reduction was found to be nonlinear.
Determination of the Orientation of the Crystallographic Axes in Anisometric Particles by Infrared Spectroscopy
Authors: Morales M. P. , Nuñez N. O. , Pozas R. , Ocaña M. , Serna C. J.
Published: October 2003

The applicability of IR spectroscopy for the determination of the orientation of the crystallographic axes in uniform anisometric particles is discussed for the case of monocrystalline hematite particles. Two samples consisting of uniform particles of similar size (∼300 nm in length) and shape (axial ratio ∼5) obtained by different preparation methods have been used in this study. It is shown that in spite of the similar composition, crystalline structure, and morphological characteristics of the samples, their IR spectra present important variations in the position and relative intensity of the absorption bands due to the different orientations of the crystallographic axes. Such behavior can be accounted for by the effective medium theory using the optical constants of hematite. Therefore, from the analysis of the IR spectrum of a powder, it is possible to identify the orientation of the crystallographic axes of the constituent anisometric particles. These results have been corroborated by electron diffraction carried out on individual particles.
Design and Evaluation of a Near-Infrared Dispersive Spectrometer That Uses a He-Ne Laser for Automatic Internal Wavelength Calibration
Authors: Busch Kenneth W. , Rabbe Dennis , Humphrey Karalyn , Busch Marianna A.
Published: October 2003

A diffraction-grating near-infrared spectrometer that uses a He–Ne laser for automatic internal wavelength calibration is described. The instrument uses the known location of the higher diffraction orders of the 632.8-nm laser line to perform wavelength calibration in the near-infrared region. The wavelength accuracy of the dispersive spectrometer was compared with that of a Fourier transform near-infrared spectrometer whose wavelength scale was validated by calibration with the known spectrum of ethyne. The average absolute wavelength deviation between the two spectrometers for four isolated bands of trichloromethane was found to be +0.12 nm. The average values of the wavelengths of four isolated bands of trichloromethane obtained with the two spectrometers used in this study were determined to be: 1151.62 ± 0.28 nm (3 ν1), 1410.74 ± 0.52 nm (2 ν1 + ν4), 1692.38 ± 0.49 nm (2 ν1), and 1860.20 ± 0.16 nm ( ν1 + 2 ν4).
Real-Time Monitoring of the Oligomerization Reaction of Bis(Hydroxyethyl Terephthalate) by Near-Infrared Spectroscopy and Chemometrics
Authors: Amari Toru , Ozaki Yukihiro
Published: October 2003

The initial oligomerization of bis(hydroxyethyl terephthalate), BHET, was monitored in situ by near-infrared (NIR) spectroscopy with a transmission probe. The amount of hydroxyl end groups, which is a function of the degree of oligomerization, and the amount of ethylene glycol (EG) in the reaction solution were successfully predicted by the NIR spectra combined with partial least-squares (PLS) regression using measured values from 1H-NMR. The models for predicting the amounts of the OH end groups and EG were interpreted by plots of regression coefficients. Although the amount of EG was small, it was possible to extract spectral information about EG by use of these loading plots. This study is a sequel to the previous study that used an attenuated total reflection (ATR) infrared (IR) method. In the last part of this paper we compare the present results obtained by NIR spectroscopy with those by ATR-IR spectroscopy.
Near-Infrared Spectroscopic Study of Interaction between Methyl Group and Water in Water—Methanol Mixtures
Authors: Adachi Daisuke , Katsumoto Yukiteru , Sato Harumi , Ozaki Yukihiro
Published: October 2003

Near-infrared spectra were measured for water–methanol mixtures with a methanol content of 0–100 wt % at 25 °C. The second derivative of the NIR spectra clearly reveals that the first overtones of the CH3 asymmetric stretching modes of methanol near 5950 and 5900 cm−1 show a downward shift by about 30 cm−1 with the increase in the concentration of methanol. This is unambiguous evidence for the direct interaction of the CH3 group of methanol with the OH group of water. Similar downward shifts were also observed for water–ethanol and water–1-propanol mixtures, although the shifts are much smaller for the water–ethanol and water–1-propanol mixtures. Based upon the results of NIR spectra, we propose a model for the interaction between the C–H bond of the CH3 group of methanol and water. This intermolecular interaction is analogous to the intramolecular “(O) CH … O” interaction in compounds having both a CH3 group binding to an oxygen atom and an OH group. This paper demonstrates novel potential of NIR spectroscopy in investigating interactions containing a C–H bond.
Photophysical and Direct Determination of Binding Constants of Ethidium Bromide Complexed to E. Coli DNA
Authors: Talavera Eva M. , Guerrero Pablo , Ocana Francisco , Alvarez-Pez Jose M.
Published: October 2003

High-precision time-correlated single-photon-counting data were obtained to achieve the resolution of the fluorescence decay time components from DNA-Ethidium bromide (Eb) buffered solutions at low (0.05 M) and high (0.4 M) NaCl concentrations. Tri-exponential functions are the best models to describe the decay kinetics in all solutions, independently of the NaCl concentration. The fluorescence nanosecond graphs were recorded intercalating polarizers into the light path to check for anisotropy artifacts. The results suggest that the three exponentials from fluorescence decay graphs depict three true lifetimes, which, in general, are dependent on the [DNA]/[Eb] ratio and can be assigned to free Eb and bound Eb at the low- and high-affinity DNA sites. With the normalized weighting coefficients from tri-exponential fitting of nanosecond decay graphs, recorded at the excitation wavelength of the isosbestic point, it has been possible to calculate the values of binding constants and site numbers at the two salt concentrations by means of the neighbor exclusion model (McGhee–von Hipple expression).
Effect of Ar and O2 Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate
Authors: Gordillo-Vázquez F. J. , Perea A. , Afonso C. N.
Published: October 2003

The influence of gas atmospheres (at 1 torr) of different natures, both reactive (O2) and inert (Ar), on the spatial evolution of the electron temperature ( Te) and electron density ( Ne) of the plasma generated by laser ablation of a LiNbO3 target is evaluated by optical emission spectroscopy techniques. It is found that the behavior of Ne in the plasma produced in vacuum, argon, and oxygen atmospheres exhibit quite different trends as a function of the distance from the target to the substrate, but the behavior of Te is nearly constant. The spatial constancy of Te in all the atmospheres studied is probably related not only to the low laser irradiance used (0.06 GW cm−2), but also to a possible collisional decoupling of the heavy species in the central part of the expanding plasma plume where a low pressure region is formed. The fact that Ne is lower in Ar than in O2 indicates the presence of fewer positive ions in the plasma generated in Ar. The impact of this result on the better crystallinity observed in the LiNbO3 films grown in Ar is also discussed.
Cavity Ringdown Spectroscopy for Diagnostic and Analytical Measurements in an Inductively Coupled Plasma
Authors: Wang Chuji , Mazzotti Fabio J. , Miller George P. , Winstead Christopher B.
Published: October 2003

The use of cavity ringdown spectroscopy (CRDS) for atomic absorption measurements in a 27-MHz low-power argon inductively coupled plasma (ICP) is described. These results are used to demonstrate the utility of CRDS for both plasma diagnostic and analytical measurements. In these experiments, an aqueous solution of lead was introduced into a modified torch designed to enhance the ICP conditions for atomic absorption measurements. Absorption intensity characteristics of the lead 283.3-nm absorption line as a function of observation height and lateral position in the plasma were recorded for three different ICP powers (700, 500, and 200 W). The radial distribution of the ground-state lead atom density was derived from Abel inversion of the lateral measurements. At the novel 200 W operating condition, spectral line shapes vs. height and lateral position were fitted to Voigt profiles. Line-of-sight values of the gas kinetic temperature and electron density at different plasma locations were estimated from Gaussian and Lorentzian broadening components, respectively. The results are discussed and compared with those from other methods. The unique flexibility of CRDS for atomic and ionic absorption measurements in an ICP and the potential application of the ICP-CRDS technique for analytical measurements are demonstrated. Analytical results are compared with theoretical estimates of the lead detection limit.
Fourier Transform Raman Spectroscopy of Honey
Authors: De Oliveira Luiz Fernando C. , Colombara Rosana , Edwards Howell G. M.
Published: October 2003

In this work we present the Fourier transform Raman spectra of several commercial samples of honey in different states, comprising nine crystallized and three fluid samples. The measured water content of the specimens bears no relationship to their fluid behavior. The relative intensities of the vibrational bands in the C–H stretching region of the FT-Raman spectra are found to be sensitive to the observed physical states of the specimens. Several observed vibrational bands in the region 500–1800 cm−1 could be identified as fingerprints of the two major components in honey, fructose, and glucose, and at least one vibrational band was characteristic of sucrose. A relationship between the bandshape of the C–H stretching bands of honey specimens and their fluid properties was noted; crystallized samples show a well-resolved distinctive spectrum in this region, whereas the fluid samples do not exhibit this pattern. Some minor differences in the FT-Raman spectra of the honey specimens are discussed in terms of composition (saccharides and water) and the fluid state of the samples.
Direct Identification and Quantitative Determination of Acidic and Neutral Diterpenes Using 13C-NMR Spectroscopy. Application to the Analysis of Oleoresin of Pinus nigra
Authors: Rezzi Serge , Bighelli Ange , Castola Vincent , Casanova Joseph
Published: October 2003

We report a methodology that allows identification and quantitative detrmination of individual acidic and neutral diterpenes in natural mixtures, using the computer-aided analysis of their 13C-NMR spectra. The analytical procedure was validated on artificial mixtures and then applied to authentic oleoresins of Pinus nigra. Up to eleven diterpenes, which represented 63% of the total composition of the oleoresin, were identified and quantified without previous separation or derivatization.
Quantitative Depth Profiling Using Saturation-Equalized Photoacoustic Spectra
Authors: Jones Roger W. , McClelland John F.
Published: October 2003

Depth profiling using photoacoustic spectra taken at multiple scanning speeds or modulation frequencies is normally impaired by the increase in spectral saturation that occurs with decreasing speed or frequency. Photothermal depth profiling in general is also impeded by the ill conditioned nature of the mathematical problem of determining a depth profile from photothermal data. This paper describes a method for reducing the saturation level in low-speed or low-frequency spectra to the level at high speed or frequency so that all spectra have the same saturation. The conversion method requires only magnitude spectra, so it is applicable to both conventional and phase-modulation photoacoustic spectra. This paper also demonstrates a method for quantitative depth profiling with these converted spectra that makes use of prior knowledge about the type of profile existing in a sample to reduce the instabilities associated with the mathematically ill conditioned task.
Nonlinear Optimization Algorithm for Multivariate Optical Element Design
Authors: Soyemi Olusola O. , Haibach Frederick G. , Gemperline Paul J. , Myrick Michael L.
Published: October 2003

A new algorithm for the design of optical computing filters for chemical analysis, otherwise known as multivariate optical elements (MOEs), is described. The approach is based on the nonlinear optimization of the MOE layer thicknesses to minimize the standard error in sample prediction for the chemical species of interest using a modified version of the Gauss–Newton nonlinear optimization algorithm. The design algorithm can either be initialized with random layer thicknesses or with layer thicknesses derived from spectral matching of a multivariate principal component regression (PCR) vector for the constituent of interest. The algorithm has been successfully tested by using it to design various MOEs for the determination of Bismarck Brown dye in a binary mixture of Crystal Violet and Bismarck Brown.
Principal Discriminant Variate Method for Classification of Multicollinear Data: Applications to Near-Infrared Spectra of Cow Blood Samples
Authors: Jiang Jian-Hui , Tsenkova Roumiana , Wu Yuqing , Yu Ru-Qin , Ozaki Yukihiro
Published: October 2003

A new regularized discriminant analysis technique, the principal discriminant variate (PDV) method, has been developed for effectively handling multicollinear data commonly encountered in multivariate spectroscopy-based classification. The motivation behind this method is to seek a sequence of discriminant directions that not only optimize the separability between different classes, but also account for a maximized variation present in the data. This motivation furnishes the PDV method with improved stability in prediction without significant loss of separability. Different formulations for the PDV methods are suggested, and an effective computing procedure is proposed for a PDV method. Two sets of near-infrared (NIR) spectra data, one corresponding to the blood plasma samples from two cows and the other associated with the whole blood samples from mastitic and healthy cows, have been used to evaluate the behavior of the PDV method in comparison with principal component analysis (PCA), discriminant partial least-squares (DPLS), soft independent modeling of class analogies (SIMCA), and Fisher linear discriminant analysis (FLDA). Results obtained demonstrate that the NIR spectra of blood plasma samples from different classes are clearly discriminated by the PDV method, and the proposed method provides superior performance to PCA, DPLS, SIMCA, and FLDA, indicating that PDV is a promising tool in discriminant analysis of spectra-characterized samples with only small compositional differences.
Pattern Recognitions of Band Shifting, Overlapping, and Broadening Using Global Phase Description Derived from Generalized Two-Dimensional Correlation Spectroscopy
Authors: Morita Shin-Ichi , Ozaki Yukihiro
Published: October 2003

In this paper we propose a new method for pattern recognitions of band shifting, overlapping, and broadening using a global phase map derived from generalized two-dimensional correlation spectroscopy (global 2D phase map). To obtain the distinct patterns for band shifting, overlapping, and broadening, original spectra are subjected to scaling so that the spectra after the scaling do not cross one another. After such pretreatment the band shifting creates the tilting of a correlation plane, the band overlapping yields four flat terraces, and the band broadening generates an asymmetric curved plane with respect to the diagonal line in the global 2D phase map. An example of the application of this method has been investigated using two bands due to the CH2 symmetric stretching and CN stretching vibrations in temperature-dependent infrared (IR) transmission spectra of an eleven-layer Langmuir–Blodgett (LB) film of 2-dodecyl-7,7,8,8-tetracyanoquinodimethane (dodecyl-TCNQ). The global 2D phase maps develop the clearly distinct patterns due to the shifting, overlapping, and broadening even if the shifting and broadening bands are overlapped with other bands.
Diffusion Measurements Using FT-IR ATR Spectroscopy: Lubricant Diffusion in Polypropylene
Authors: Yi Xiaohua , Nerbonne Karen , Pellegrino John
Published: October 2003

We present an experimental method for measuring diffusion of lubricants (or any highly viscous fluid) in polymers using Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy. Unlike the conventional FT-IR ATR diffusion measurement, in which a polymer sample is sandwiched between the penetrant and an internal reflection element (IRE), in this method, a thin layer of penetrant (for example, a lubricant) is sandwiched between the IRE and the polymer sample. This allows accurate control and measurement of the thickness of the lubricant layer, which, in turn, facilitates subsequent data analysis. The diffusion is studied by monitoring the time-resolved change in absorbance of either a unique polymer or penetrant band. A feature of this new method is that it can provide an estimate of solubility, as well as an estimate of the diffusivity of the penetrant in the polymer. Using this method, we studied the diffusion of mineral oil and a commercial fluorocarbon ether lubricant (Krytox® 143AC‡) in poly(propylene) (PP) film at room temperature. The experimental data was modeled using a Fickian model with impermeable and saturated boundary conditions applied at the IRE/lubricant and lubricant/polymer interfaces, respectively. The diffusivity and solubility of mineral oil in PP were found to be 1.34 ± 0.35 (×10−10) cm2/s and 0.77 ± 0.13 (×10−2) g/g of PP, respectively. The current model was unable to quantitatively describe the diffusion of the Krytox® 143AC in the PP, possibly due to excessive swelling.
Comparison of Calibration Methods for the Monitoring of a Fluorobenzene Batch Reaction Using Low-Field 19F NMR, 1H NMR, NIR, and Raman Spectrometries
Authors: Nordon Alison , Meunier Céline , McGill Colin A. , Littlejohn David
Published: October 2003

The suitability of different process spectrometry techniques has been assessed, in terms of calibration requirements, accuracy, and precision, for the at-line monitoring of the sulfonation of fluorobenzene. Partial least-squares (PLS) calibration was required to analyze the spectra obtained by NIR spectrometry and low-field (29.1 MHz) 1H NMR spectrometry. The low-field (27.4 MHz) 19F NMR spectra contained well-resolved signals for the three fluorine containing compounds and univariate calibration was adequate. The Raman spectra of two of the compounds exhibited fluorescence and so this technique was not considered suitable for monitoring the reaction. The accuracy of the results obtained using univariate analysis of the 19F NMR data and PLS analysis of NIR data were comparable (average % error of 3.5 and 2.9%, respectively, for concentrations >0.5 mol dm−3 and 11.3 and 11.1%, respectively, for <0.5 mol dm−3). The least accurate results were obtained using PLS analysis of low-field 1H NMR data, as the spectra of two of the components were too similar. For concentrations >0.05 mol dm−3, the most precise results were obtained with PLS analysis of NIR data (average RSD of 1.6%), although the precision of the results obtained using univariate analysis of 19F NMR data was still good (average RSD of 3.7%).
Progress toward the Rapid Nondestructive Assessment of the Floral Origin of European Honey Using Dispersive Raman Spectroscopy
Authors: Goodacre Royston , Radovic Branka S. , Anklam Elke
Published: October 2003

Raman spectroscopy was investigated for its ability to discriminate between honey samples from different floral and geographical origins. The major vibrational modes in the Stokes Raman spectra were assigned and could be attributed to the four main sugars found in the honeys. The chemometric clustering method of discriminant function analysis indicated that the major differences between the honeys was due to their botanical origin rather than their country of origin, and this was confirmed by artificial neural network analyses. We consider the noninvasive nondestructive analysis of honey by Raman spectroscopy to be an alternative to the laborious and highly specialized mellisopalynology typing method currently used to identify the floral origin of honey.
Confocal Micro-Raman Spectroscopy: Theory and Application to a Hybrid Polymer Coating
Authors: Baia L. , Gigant K. , Posset U. , Schottner G. , Kiefer W. , Popp J.
Published: October 2003

Confocal micro-Raman spectroscopy has been applied for vibrational investigations on a sol-gel derived hybrid polymer coating. In order to characterize the dimensions of the focus inside the coating, the substrate, and the coating/substrate, a model that considers both the refraction and diffraction effects has been developed. A coating of ∼20.2 μm thickness applied to polycarbonate substrate has been investigated. The spatial distribution of the Raman intensity in the focal volume was studied at different depths within the sample and the Raman response at the corresponding levels has been calculated. The selection in depth of the Raman response, given by the confocal pinhole, was also taken into account. In comparing the prediction of this theoretical model to the empirical results, a good agreement has been observed.
Single Nanoparticle Trapping Using a Raman Tweezers Microscope
Authors: Ajito Katsuhiro , Torimitsu Keiichi
Published: October 2003

We have obtained a Raman spectrum of single nanometer-sized particles (nano-particles) trapped by laser tweezers for the first time. The microscope used in this study is a new version of our Raman tweezers microscope (RTM); it contains an oil-immersed objective lens with high numerical aperture to increase the force of the optical radiation pressure of the near-infrared laser beam to trap single organic and biological nanoparticles and provides sufficient sensitivity for the Raman measurement of the trapped nano-particles. The confocal arrangement in the system completely eliminates the Raman signal of the oil under the objective lens. The RTM provides a Raman spectrum of a single polystyrene latex bead about 40 nm in diameter with an exposure time of 3 s and allows us to determine its molecular species. Furthermore, the RTM enables us to count the number of nanoparticles in the focal spot of the laser beam from the Raman spectra of trapped nanoparticles.
Chemical Structure-Based Three-Dimensional Reconstruction of Human Cortical Bone from Two-Dimensional Infrared Images
Authors: Ou-Yang Hou , Paschalis Eleftherios P. , Boskey Adele L. , Mendelsohn Richard
Published: October 2003

A method is described for the construction of three-dimensional infrared images from serial two-dimensional infrared images of various chemical structure parameters acquired from cortical bone. A series of serial cortical bone sections, each 4–5 μm thick, separated by ∼100 μm, were microtomed from PMMA-embedded normal human tibia. Twenty-three IR image cubes were acquired from this series, corresponding to an overall sample length of ∼2.2 mm. From each image cube, IR images of the spatial distribution of the mineral-to-matrix (protein) ratio, the mineral crystallinity, and the ratio of nonreducible-to-reducible collagen crosslinks were calculated. Two-dimensional images were stacked to form a 3D view of the cortical bone, with contrast provided by variation in the spatial distribution of any of the aforementioned chemical/molecular structural parameters.
Laser-Induced Breakdown Spectroscopy for the Analysis of 150-Year-Old Daguerreotypes
Authors: Anglos D. , Melesanaki K. , Zafiropulos V. , Gresalfi M. J. , Miller John C.
Published: October 2003

Laser-induced breakdown spectroscopy, or LIBS, has been used to characterize the elemental composition of the surface and interior of nineteenth-century, metal-based photographs called daguerreotypes. A surface plasma was produced by the infrared beam of a nanosecond Nd:YAG laser and the emitted light was dispersed in a monochromator to yield the spectroscopic identification of elements. Major components of the daguerreotype surface included silver, copper, and gold. The gold was only present on the surface, as evidenced by its absence after the first one or two laser shots. Minor components such as silicon, aluminum, calcium, and magnesium reflect contaminant particles arising primarily from the cover glass. Several “colored” or “tinted” daguerreotypes were analyzed and the pigments identified. Depth profiling, accomplished by monitoring the spectra as a function of multiple laser shots, allowed the thickness of the silver layer to be measured as the ablation laser “drilled” into the surface. The LIBS technique is shown to be useful in understanding the composition of daguerreotypes and for identifying the specific pigments used by the photographer. These data also provide a scientific basis for attempts to optimize laser cleaning of tarnished daguerreotypes and may also provide clues to the provenance of particular examples.
Effective Normalization Technique for Correction of Matrix Effects in Laser-Induced Breakdown Spectroscopy Detection of Magnesium in Powdered Samples
Authors: Gornushkin S. I. , Gornushkin I. B. , Anzano J. M. , Smith B. W. , Winefordner J. D.
Published: October 2003

The goal of this research was to investigate the influence of the matrix on the laser-induced spectroscopy of magnesium. Powdered samples were used and were presented to the measurement as thin distributions on adhesive tape. A wide range of NIST certified reference materials were used as samples. With careful sample preparation and correction for sample surface density on the tape (determined by weighing), reasonable consistency in the Mg signal intensity was obtained regardless of sample matrix. Relative error of ∼10% and a precision of 10–20% were obtained for the determination of Mg in several certified samples.
Laser-Induced Breakdown Spectroscopy for the On-Line Multielement Analysis of Highly Radioactive Glass Melt. Part I: Characterization and Evaluation of the Method
Authors: Yun Jong-Il , Klenze Reinhardt , Kim Jae-Il
Published: October 2003

Laser-induced breakdown spectroscopy (LIBS) is presented for the on-line multielement analysis of molten radioactive glass at a simulated vitrification process of high level liquid waste (HLLW). A plasma plume is produced by focusing the third harmonic of a Nd: YAG laser (λ = 355 nm) onto the glass melt surface at 1200 °C, and the plasma emission is guided via optical fiber and is characterized by an echelle spectrometer for the spectral range from 200 to 780 nm with a resolution of ±0.01 nm. Compared to a Czerny–Turner spectrometer, the echelle spectrometer appears distinctively superior for its broad operational spectral range and high resolution. The laser-induced plasma is found as optically thin and locally in thermodynamic equilibrium (LTE) as characterized by measuring the electron density and plasma temperature. The matrix temperature effect on the spectral emission is observed as significant, increasing the emission line intensities with increasing temperature, but differently from element to element. The applicability of LIBS is demonstrated on a laboratory scale with an inactive simulated HLLW glass melt for various analytical characteristics concerned.
Molecular Emission Spectroscopy as a Potential Diagnostic Tool in Plasma-Assisted Incineration
Authors: Filion Julie , Munz Richard J. , Salin Eric D.
Published: October 2003

This paper reports on a simple analytical procedure used to demonstrate the technical feasibility of adaptive plasma-assisted incineration. APAI is a novel concept that addresses current difficulties in the treatment of hazardous organic waste. It features continual optimization of a plasma afterburner's operating conditions for cost-effective destruction of persistent contaminants under variable feed loads. Hence, on-line composition monitoring is a key element of the process. A diagnostic method was specifically developed for an experimental model system that required optical measurements from the jet of a 25–kW induction plasma torch. The method used photodiode array detection of visible emission from the Swan band system of C2 to track the destruction of organic compounds. This rapid, simple, and inexpensive procedure proved adequate for demonstration purposes.
Remote Fiber-Optic Flow Cell for the Detection of Uranium(VI) in Groundwater
Authors: Collins Greg E. , Lu Qin , Abubeker Sitra , Vajs Elizabeth
Published: October 2003

Optimization and initial characterization of a remote probe for extremely low levels (<20 μg/L) of uranium(VI) in groundwater are described. The monitor takes advantage of a small length of Nafion cation exchange membrane tubing, which permits diffusion of the uranyl ion into an internally renewable reagent solution of Arsenazo III. The sensitive, colorimetric metal complexation of uranium(VI) by Arsenazo III is measured by recording the absorbance change in a fiber-optic SMA Z-cell that is coupled to a red-light-emitting diode. The entire system is packaged on a 2 × 11 in. breadboard and attached to a 100-ft power and data transmission cord. The final optimized pH of 1.5 was utilized for maximizing sensitivity to uranium while minimizing interferences from other metal ion impurities. The addition of 1 mM diethylenetriaminepentaacetic acid to the reagent further assisted in the elimination of metal ion interferences. Two Nafion membrane tubings with different internal diameters and wall thicknesses are evaluated. Using a 20 min diffusion time and the Nafion 20 membrane, the detection limit obtained for uranium(VI) in groundwater was 1.4 ppb. Of the twenty metal ion interferents examined, all gave essentially no response, with the exception of calcium and thorium, for which a 30 mg/L and a 100 μg/L solution, respectively, gave signals representative of 4.7 and 6.0 ppb uranium(VI).
Correction of Nonlinear Effects in Absorbance Measurements
Authors: Offersgaard Jesper Falden , Öjelund Henrik
Published: October 2003

A method is introduced for prediction of the true spectral absorbance at a given wavelength from an absorbance measurement that is affected by various deficiencies of the spectral measurement channel such as finite bandwidth, cross-over at unwanted wavelength, and signal bypassing the sample. These are unwanted effects that violate the validity of the Beer–Lambert law by introducing a nonlinear dependency between the concentration and the measured absorbance. The method is based on a simple physical model of the spectral measurement channel. It may be used even for applications where only one or a few spectral channels are used, e.g., for instruments based on optical filters. The method is applied to a wastewater NO x sensor consisting of two filter-based spectral channels for absorption measurement in the UV region. Simulations show that dramatic improvement in the accuracy is obtained by introducing only one additional parameter for nonlinear correction as compared to the linear model. Calibration of the model is discussed.
Development of a New Measurement Unit (MilkSpec-1) for Rapid Determination of Fat, Lactose, and Protein in Raw Milk Using Near-Infrared Transmittance Spectroscopy
Authors: Woo Young-Ah , Terazawa Yoko , Chen Jie Yu , Iyo Chie , Terada Fuminori , Kawano Sumio
Published: October 2003

A new measurement unit, the MilkSpec-1, has been developed to determine rapidly and nondestructively the content of fat, lactose, and protein in raw milk using near-infrared transmittance spectroscopy. The spectral range over 700 to 1100 nm was used. This unit was designed for general glass test tubes, 12 mm in diameter and 10 mL in volume. Al2O3 with a thickness of 2.5 mm was found to be optimum as a reference for acquiring the milk spectrum for this measurement. The NIR transmittance spectra of milk were acquired from raw milk samples without homogenization. The calibration model was developed and predicted by using a partial least-squares (PLS) algorithm. In order to reduce the scattering effect due to fat globules and casein micelles in NIR transmittance spectra, multiplicative scatter correction (MSC) and/or second derivative treatment were performed. MSC treatment proved to be useful for the development of calibration models for fat and protein. This study resulted in low standard errors of prediction (SEP), with 0.06, 0.10, and 0.10% for fat, lactose, and protein, respectively. It is shown that accurate, rapid, and nondestructive determination of milk composition could be successfully performed by using the MilkSpec-1, presenting the potential use of this method for real-time on-line monitoring in a milking process.
Concentration Residual Augmented Classical Least Squares (CRACLS): A Multivariate Calibration Method with Advantages over Partial Least Squares
Authors: Melgaard David K. , Haaland David M. , Wehlburg Christine M.
Published: October 2003

A significant extension to the classical least-squares (CLS) algorithm called concentration residual augmented CLS (CRACLS) has been developed. Previously, unmodeled sources of spectral variation have rendered CLS models ineffective for most types of problems, but with the new CRACLS algorithm, CLS-type models can be applied to a significantly wider range of applications. This new quantitative multivariate spectral analysis algorithm iteratively augments the calibration matrix of reference concentrations with concentration residuals estimated during CLS prediction. Because these residuals represent linear combinations of the unmodeled spectrally active component concentrations, the effects of these components are removed from the calibration of the analytes of interest. This iterative process allows the development of a CLS-type calibration model comparable in prediction ability to implicit multivariate calibration methods such as partial least squares (PLS) even when unmodeled spectrally active components are present in the calibration sample spectra. In addition, CRACLS retains the improved qualitative spectral information of the CLS algorithm relative to PLS. More importantly, CRACLS provides a model compatible with the recently presented prediction-augmented CLS (PACLS) method. The CRACLS/PACLS combination generates an adaptable model that can achieve excellent prediction ability for samples of unknown composition that contain unmodeled sources of spectral variation. The CRACLS algorithm is demonstrated with both simulated and real data derived from a system of dilute aqueous solutions containing glucose, ethanol, and urea. The simulated data demonstrate the effectiveness of the new algorithm and help elucidate the principles behind the method. Using experimental data, we compare the prediction abilities of CRACLS and PLS during cross-validated calibration. In combination with PACLS, the CRACLS predictions are comparable to PLS for the prediction of the glucose, ethanol, and urea components for validation samples collected when significant instrument drift was present. However, the PLS predictions required recalibration using nonstandard cross-validated rotations while CRACLS/PACLS was rapidly updated during prediction without the need for time-consuming cross-validated recalibration. The CRACLS/PACLS algorithm provides a more general approach to removing the detrimental effects of unmodeled components.
Multicomponent Assay for Human Serum Using Mid-Infrared Transmission Spectroscopy Based on Component-Optimized Spectral Region Selected by a First Loading Vector Analysis in Partial Least-Squares Regression
Authors: Kim Yoen-Joo , Yoon Gilwon
Published: October 2003

Mid-infrared transmission spectroscopy with partial least-squares regression was used to determine the concentrations of blood components such as total protein, albumin, globulin, total cholesterol, HDL (high density lipoprotein) cholesterol, triglycerides, glucose, BUN (blood urea nitrogen), and uric acid in human serum. The optimal spectral region for each component was selected by first loading vector analysis. Positive peaks with positive value were assigned by first loading vector analysis. Because blood components in serum show a correlation among several components, a useful spectral region for predicting a particular component was selected such that its spectral feature was not overlapped by those of other components. Several regions with positive peaks by first loading vector were used to establish calibration models. The proposed method proved to be effective for a multicomponent assay and can also be used even when a single component spectrum in aqueous solution for all components is not known. Total protein, albumin, globulin, total cholesterol, triglycerides, and glucose have a mean percentage error of cross-validation (MPECV) of less than 5%. But HDL cholesterol, BUN, and uric acid have MPECVs between 12 and 18%. In terms of both the percentage error of cross-validation and clinically allowable error, six serum components, excepting HDL-cholesterol, BUN, and uric acid, were determined successfully.
Analysis of Noise in Fourier Transform Infrared Spectra
Authors: Mark Howard L. , Griffiths Peter R.
Published: October 2003

The currently accepted theory of spectroscopic noise causes most spectroscopists to accept the statement that when the limiting noise source is constant detector noise (e.g., as in mid- and near-IR spectroscopy) the noise of a transmittance spectrum is also constant, and independent of the sample transmittance. A careful examination of the effect of noise on spectra, however, reveals that most of the previous derivations have neglected the effect of noise in the reference reading on the noise content of the spectra. The consequences range from the fact that even with constant detector noise, the error of a transmittance spectrum is NOT constant, to the fact that the optimum value of sample transmittance, to obtain best relative precision, is not 36.8%, as usually stated, but 33%. We also present the results of experiments performed to distinguish between the results predicted by the two theories and to verify that taking the reference noise into account does, in fact, make a difference. “The trouble with the world is not that people know too little, it's that they know so many things that ain't so.” (Mark Twain)
Spectroscopic Characterization of Normal Primary and Malignant Cells Transformed by Retroviruses
Authors: Huleihel Mahmoud , Erukhimovitch Vitaly , Talyshinsky Marina , Karpasas Mark
Published: October 2003

Microscopic FT-IR spectroscopy was used to investigate spectral differences between various primary cells obtained from different sources (mouse, rat, rabbit, and human) and malignant cells transformed by murine sarcoma virus (MuSV). The advantage of this method over conventional FT-IR spectroscopy is that it facilitates inspection of restricted regions of tissue. Our results showed significant and consistent differences between all the tested normal and malignant cells. An impressive decrease in the levels of vital cellular metabolites was seen in malignant cells compared to normal cells. The peak attributed to the PO2− symmetric stretching mode at 1082 cm−1 was shifted significantly to a higher frequency (1086–1087 cm−1) in all the tested malignant cells. The impressive and consistent differences between normal primary cells and malignant cells (obtained from various organs and species) in the shapes and position of various bands throughout the spectrum strongly support the possibility of developing FT-IR microscopy as a diagnostic method for the detection and study of cancer cells.
Effect of Pressing on the Infrared Spectra of Single Cotton Fibers
Authors: Chen Runying , Jakes Kathryn A.
Published: October 2003

Fourier transform infrared spectra of single fibers of cotton and 18% NaOH treated cotton were obtained before and after fiber pressing to investigate the effect of pressing on the sample. Pressing resulted in improved spectral quality in some regions (e.g., OH stretching) and deteriorated spectral quality in other regions (e.g., CH stretching). Second derivatives of these IR spectra reveal alterations in vibration modes. Thin immature cotton was included in this study to provide a comparison to fibers thinned by pressing. Infrared crystallinity indices, i.e., the ratio of A1370/A2900 differ between the pressed and unpressed cotton fibers. Because both quantitative and qualitative changes can result from compression of cotton fibers, caution is required in both selection of the sample preparation method and in interpretation of the infrared spectra.
Attenuated (but Not Total) Internal Reflection FT-IR Spectroscopy of Thin Films
Authors: Cantrell Will , Ewing George E.
Published: October 2003

We present a spectroscopic technique that is a hybrid between reflection-absorption and attenuated total reflection (ATR) spectroscopy. The method, which we call attenuated internal reflection (AIR), is suitable for the investigation of thin film liquids on non-or weakly absorbing substrates. In AIR the interrogating infrared beam is not exposed to vapor that may be associated with the film, but unlike ATR there are few geometric constraints on the substrate. We show the theoretical basis for the method and results from experiments demonstrating its use.
Preparation of Stable, Reproducible Silver Colloids for Use as Surface-Enhanced Resonance Raman Scattering Substrates
Authors: Keir Ruth , Sadler Daran , Smith W. E.
Published: October 2003

A flow system for the production of stable, reproducible batches of silver colloid for use as substrates for surface-enhanced resonance Raman spectroscopy (SERRS) is described. The colloids were prepared by borohydride reduction of silver nitrate and subsequent stabilization was achieved by adding trisodium citrate. The batches of colloid produced were analyzed using UV-visible spectroscopy and their suitability for use as SERRS substrates was assessed using 3,5-dimethoxy-4-(5′-azobenzotriazole)phenylamine as the analyte. SERRS analysis was carried out using a flowcell. Using the method described, batches of silver colloid were prepared that were stable for at least five months and when used as SERRS substrates resulted in a relative standard deviation in SERRS intensity of 3,5-dimethoxy-4-(5′-azobenzotriazole)phenylamine of 6.6% between colloid batches. The robustness of the system for production of stable, reproducible colloids was assessed using experimental design. The final method proposed enables reproducible, time-stable colloid to be made in a simple manner, thus eliminating one of the major problems associated with the use of SERRS detection in analytical procedures.
Investigation of Normal and Malignant Tissue Samples from the Human Stomach Using Fourier Transform Raman Spectroscopy
Authors: Ling X.-F. , Xu Y.-Z. , Weng S.-F. , Li W. H. , Zhi Xu , Hammaker R. M. , Fateley W. G. , Wang F. , Zhou X.-S. , Soloway R. D. , Ferraro J. R. , Wu J.-G.
Published: October 2003

Fourier transform (FT) Raman studies of 40 tissue samples from the human stomach, including 22 normal and 18 malignant tissue samples, were performed. These stomach tissue samples had been classified as normal or malignant on the basis of pathological studies and biopsy detection. The results indicate that a series of major bands in the FT-Raman spectrum can be used to distinguish the malignant tissue from the normal tissue. Subtraction spectra support the result of the spectroscopic identification. Statistical analysis is also in agreement with the FT-Raman measurements.