Forensic classification of nail polish via ATR-IR and Raman spectroscopy: an artificial intelligence-based approach.

Comparison between ATR-IR, Raman, concatenated ATR-IR and Raman spectroscopy for the determination of total antioxidant capacity and total phenolic content of Chinese rice wine

Development of an efficient catalyst in heterogeneous catalysis includes understanding the relationship between catalyst structure and its activity. In situ spectroscopy methods can be used to study structure of the catalytic active site and reaction sequences under reaction conditions. Information obtained from such analyses, e.g. the structure of the surface species responsible for catalyst deactivation or the changes in catalyst structure under the reaction conditions, can suggest routes for catalyst improvement. However, the limited applicability of the techniques in real reaction conditions and especially in the presence of a solvent can be a challenge for in situ investigations. Attenuated Total Reflection Infrared (ATR-IR) spectroscopy, discussed in detail in this thesis, is a technique used for studies at solid/water interface. The main target of the work is applicability of the ATR-IR spectroscopy for in situ studies of the water/catalyst interface in Aqueous Phase Reforming (APR). APR reaction requires high temperatures and pressures (150 - 350 °C and 10 - 50 bar), therefore a suitable ATR-IR cell had to be designed and tested for these conditions. Results describe the design of an in situ ATR-IR Tunnel cell with a cylindrical Element coated with a catalyst layer. Hydrodynamic flow simulations showed non-plug flow behavior in the cell. Applicability of ATR-IR spectroscopy under APR conditions was demonstrated by studying the conversion of -Al2O3 to boehmite in real-time under hydrothermal conditions of APR, showing that this transformation leads to catalyst deactivation together with Pt sintering and blockage of the Pt surface with boehmite. The formation of boehmite was established by Raman spectroscopy and 27Al MAS NMR analysis of samples before and after exposure to APR conditions. The adsorption of hydroxyacetone on Pt/AlO(OH) and Pt/ZrO2 catalysts at 230 °C/ 30 bar was also studied by in situ ATR IR spectroscopy. Formation of aldol condensation products of hydroxyacetone strongly adsorbed on the surface was observed on Pt/ZrO2 and ZrO2 in contrast to Pt/AlO(OH) and AlO(OH). The amount and type of coke deposits determined by elemental analysis and TPO showed that coke with low oxidation temperatures was deposited mostly on the surface of the ZrO2 support.

Detection of cold seep derived authigenic carbonates with infrared spectroscopy

BackgroundFollowing the recent development of a new approach to quantitative analysis of IgG concentrations in bovine serum using transmission infrared spectroscopy, the potential to measure IgG levels using technology and a device better designed for field use was investigated. A method using attenuated total reflectance infrared (ATR) spectroscopy in combination with partial least squares (PLS) regression was developed to measure bovine serum IgG concentrations. ATR spectroscopy has a distinct ease-of-use advantage that may open the door to routine point-of-care testing. Serum samples were collected from calves and adult cows, tested by a reference RID method, and ATR spectra acquired. The spectra were linked to the RID-IgG concentrations and then randomly split into two sets: calibration and prediction. The calibration set was used to build a calibration model, while the prediction set was used to assess the predictive performance and accuracy of the final model. The procedure was repeated for various spectral data preprocessing approaches.ResultsFor the prediction set, the Pearson’s and concordance correlation coefficients between the IgG measured by RID and predicted by ATR spectroscopy were both 0.93. The Bland Altman plot revealed no obvious systematic bias between the two methods. ATR spectroscopy showed a sensitivity for detection of failure of transfer of passive immunity (FTPI) of 88 %, specificity of 100 % and accuracy of 94 % (with IgG <1000 mg/dL as the FTPI cut-off value).ConclusionATR spectroscopy in combination with multivariate data analysis shows potential as an alternative approach for rapid quantification of IgG concentrations in bovine serum and the diagnosis of FTPI in calves.

Adsorption of carbon monoxide and oxidation of preadsorbed carbon monoxide from gas and aqueous phases were studied on a platinum catalyst deposited on a ZnSe internal reflection element (IRE) using attenuated total reflection infrared (ATR-IR) spectroscopy. The results of this study convincingly show that it is possible to prepare platinum metal layers strongly attached to an IRE, which are stable for over 3 days in aqueous-phase experiments. It is shown that ATR-IR spectroscopy is a suitable technique to study adsorption and catalytic reactions occurring at the interface of a solid catalyst in an aqueous reaction mixture, even with an extreme low-surface-area catalyst. Clearly, ATR-IR spectroscopy allows for a direct comparison of reactions on a catalytic surface in gas and liquid phases on the same sample. CO was found to adsorb both linearly and bridged on the platinum metal layer when adsorbed from the gas phase, but only linear CO was detected in aqueous solution, although with 5 times higher intensity. Oxidation of preadsorbed CO on platinum occurs in both gas phase, wetted gas, and aqueous media and was found to be 2 times faster in the aqueous phase compared to gas-phase oxidation because of a promoting effect of water. Moreover, during oxidation at room temperature, CO2 adsorbed on Pt/ZnSe was detected in both gas and aqueous phases.

This communication presents a novel label-free biosensing method to monitor DNA hybridization via infrared attenuated total reflection (IR-ATR) spectroscopy using surface-modified ZnSe waveguides. Well-defined carboxyl-terminated monolayers were formed at H-terminated ZnSe by direct photochemical activation. Chemical activation of the acidic function was obtained by using succinimide/carbodiimide linkers. The sequential surface modification reactions were characterized by XPS and IR-ATR spectroscopy. Finally, a single stranded DNA probe with a C6-NH(2) 5' modifier was coupled to the ester-terminated surface via peptide bonding, and the hybridization of the immobilized DNA sequence with its complementary strand was directly evaluated by IR-ATR spectroscopy in the mid-infrared (MIR) spectral regime (3-20 μm) without requiring an additional label. A shift of the vibrational modes corresponding to the phosphodiester and deoxyribose structures of the DNA backbone was observed. Hence, this approach substantiates a novel strategy for label-free DNA detection utilizing mid-infrared spectroscopy as the optical sensing platform.

The degradation of poly[2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene] thin films studied by capacitance-voltage analysis and attenuated total reflection infrared spectroscopy

Effect of extracorporeal circulation on structure of main components of animal plasma - ATR-IR and 2D-COS studies. Part II: Presence of antithrombotic drugs.

The CO(2)-catalyzed acetalization is regarded as a promising alternative to the conventional acid-catalyzed method from a viewpoint of green chemistry (C. A. Eckert et al., Ind. Eng. Chem. Res. 43, 2605 (2004)). We have applied in situ attenuated total reflection infrared (ATR-IR) spectroscopy for elucidating and monitoring the acetalization of cyclohexanone in CO(2)-expanded ethylene glycol and methanol at 50 degrees C and 3 MPa. The ATR-IR spectra of the reaction mixtures periodically recorded with a ZnSe crystal demonstrate that ATR-IR spectroscopy is a practical tool for tracing the kinetics of acetalizations in situ. In addition, the rate of CO(2) dissolution as well as CO(2) solubility into the cyclohexanone-alcohol mixtures could be evaluated from the CO(2)-nu(3)-antisymmetric stretching band. The ZnSe ATR crystal, however, was corroded during longer use under the acidic conditions realized by the dissolution of CO(2) in the alcohols. In contrast, the corrosion did not occur when a Ge crystal was used instead of a ZnSe crystal, and therefore the application of a Ge ATR crystal is recommended for continuous long-term experiments with these media.

Lycopene is a potent antioxidant that has been shown to play critical roles in disease prevention. Efficient assays for detection and quantification of lycopene are desirable as alternatives to time- and labor-intensive methods. Attenuated total reflectance infrared (ATR-IR) spectroscopy was used for quantification of lycopene in tomato varieties. Calibration models were developed by partial least-squares regression (PLSR) using quantitative measures of lycopene concentration from liquid chromatography as reference method. IR spectra showed a distinct marker band at 957 cm(-1) for trans Carbon-Hydrogen (CH) deformation vibration of lycopene. PLSR models predicted the lycopene content accurately and reproducibly with a correlation coefficient (sigma) of 0.96 and standard error of cross-validation <0.80 mg/100 g. ATR-IR spectroscopy allowed for rapid, simple, and accurate determination of lycopene in tomatoes with minimal sample preparation. Results suggest that the ATR-IR method is applicable for high-throughput quantitative analysis and screening for lycopene in tomatoes.

Quantification of adamantane in organic media via infrared attenuated total reflection spectroscopy

ATR-IR study of skin components: Lipids, proteins and water. Part I: Temperature effect

Temperature dependence of molecular structure of dissolved glycine as revealed by ATR-IR spectroscopy

Opportunities exist to exploit the unique properties of superheated or near-critical water in the recycling of polymers. Exposure of polyethylene terephthalate (PET) to hot water at 180 °C and 1.0 MPa has resulted in the decomposition of PET and the formation of terephthalic acid. This process was followed, for the first time, via in situ ATR-IR spectroscopy. The high-temperature ATR-IR (attenuated total reflection infrared) approach allows the measurement of IR spectra of polymers subjected to superheated, near-critical or supercritical water. The ATR-IR spectra of liquid water in the temperature range 25–300 °C have also been measured, and evidence of the reduction in the degree of hydrogen bonding in water under these conditions has been obtained. Good potential exists to apply the approach developed here to study processes in near-critical water.

The adsorption of carbon monoxide (CO) on platinum (Pt) nanoparticles under the influence of a low electrical field (E-field) is studied. The adsorption of CO is monitored by attenuated total reflection infrared (ATR-IR) spectroscopy, while an external electrical field is applied over the microreactor. Linearly (on top; COL), bridged (two-fold hollow; COB), and multiply (three-fold hollow; COMB) adsorbed CO species were found on the Pt nanoparticles. In a sequence of adsorption experiments the integrated ATR-IR intensity of the absorption band of the linearly adsorbed COL was found to reach steady-state values after an initial decrease, which is attributed to a loss of Pt surface area due to sintering of the Pt metal nanoparticles. The application of electrical fields results in changes in the ratio between linearly adsorbed CO, on top of Pt, versus CO adsorbed on multiple Pt atoms.