Simulation of Attenuated Total Reflection Infrared Absorbance Spectra: Applications to Automotive Clear Coat Forensic Analysis

2014 ◽  
Vol 68 (5) ◽  
pp. 608-615 ◽  
Author(s):  
Barry K. Lavine ◽  
Ayuba Fasasi ◽  
Nikhil Mirjankar ◽  
Koichi Nishikida ◽  
Jay Campbell
Keyword(s):  
Forensic Analysis ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Clear Coat ◽  
Absorbance Spectra

Detoxification of a Mixture of Aliphatic Chlorinated Hydrocarbons in a Fixed-Bed Bioreactor: Continuous On-line Monitoring via an Attenuated Total Reflection-Fourier Transform Infrared Sensor

1999 ◽  
Vol 40 (8) ◽  
pp. 41-47 ◽  
Author(s):  
V. Acha ◽  
M. Meurens ◽  
H. Naveau ◽  
S. N. Agathos
Keyword(s):  
Fourier Transform ◽  
Fixed Bed ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Calibration Model ◽  
Toxic Compounds ◽  
Chlorinated Aliphatic Hydrocarbons ◽  
On Line ◽  
Absorbance Spectra

A methanogenic microbial community immobilised on an inert carrier was acclimated to a mixture of chlorinated aliphatic hydrocarbons in a bioreactor used for their detoxification. The mixture contained trichloroethylene (TCE), tetrachloroethylene (PCE), carbon tetrachloride (CT) and hexachlorobutadiene (HCB). An attenuated total reflection-Fourier transform infrared (ATR-FTIR) optical sensor was developed for continuous on-line measurements of the toxic compounds in the dechlorinating bioreactor. The sensor consisted of an ATR internal reflection element (IRE) coated with an extracting polymer which was continuously enriched with the toxic compounds. The bioprocess was monitored through the sensor, which was coupled permanently to the bioreactor, over a period of three days of continuous operation. The sensor tracked the progression of absorbance spectra over time in a non-invasive manner. The concentration of organochlorine compounds in the bioreactor was predicted from the absorbance spectra using a partial least squares (PLS) calibration model which was developed for all components simultaneously. The accuracy and reproducibility of this ATR-FTIR sensor was tested by checking the spectra-based concentration values of the toxic analytes in the bioreactor effluents against off-line gas chromatography (GC) measurements. This novel sensor is useful for routine continuous on-line monitoring of the dechlorinating bioreactor.

Development of Infrared Library Search Prefilters for Automotive Clear Coats from Simulated Attenuated Total Reflection (ATR) Spectra

2018 ◽  
Vol 72 (6) ◽  
pp. 886-895 ◽  
Author(s):  
Undugodage Don Nuwan Perera ◽  
Koichi Nishikida ◽  
Barry K. Lavine
Keyword(s):  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Discrete Wavelet ◽  
Transmission Spectra ◽  
Simulation Algorithm ◽  
Training Set ◽  
Clear Coat ◽  
Assembly Plant ◽  
Ir Transmission ◽  
Validation Set

A previously published study featuring an attenuated total reflection (ATR) simulation algorithm that mitigated distortions in ATR spectra was further investigated to evaluate its efficacy to enhance searching of infrared (IR) transmission libraries. In the present study, search prefilters were developed from transformed ATR spectra to identify the assembly plant of a vehicle from ATR spectra of the clear coat layer. A total of 456 IR transmission spectra from the Paint Data Query (PDQ) database that spanned 22 General Motors assembly plants and served as a training set cohort were transformed into ATR spectra by the simulation algorithm. These search prefilters were formulated using the fingerprint region (1500 cm−1 to 500 cm−1). Both the transformed ATR spectra (training set) and the experimental ATR spectra (validation set) were preprocessed for pattern recognition analysis using the discrete wavelet transform, which increased the signal-to-noise of the ATR spectra by concentrating the signal in specific wavelet coefficients. Attenuated total reflection spectra of 14 clear coat samples (validation set) measured with a Nicolet iS50 Fourier transform IR spectrometer were correctly classified as to assembly plant(s) of the automotive vehicle from which the paint sample originated using search prefilters developed from 456 simulated ATR spectra. The ATR simulation (transformation) algorithm successfully facilitated spectral library matching of ATR spectra against IR transmission spectra of automotive clear coats in the PDQ database.

Forensic applications of IR infrared microscopic internal reflection spectroscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1528-1529
Author(s):  
Edward G. Bartick ◽  
John A. Reffner
Keyword(s):  
Specular Reflection ◽  
Forensic Analysis ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Standard Size ◽  
Ir Microscopy ◽  
Ir Analysis ◽  
Plastic Explosives ◽  
Internal Reflection Spectroscopy ◽  
Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic–Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide

2021 ◽  
pp. 000370282199121
Author(s):  
Yuki Nakaya ◽  
Satoru Nakashima ◽  
Takahiro Otsuka
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Fulvic Acid ◽  
Spectroscopic Studies ◽  
Reaction Model ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Cell ◽  
Rate Determining Step ◽  
Ir Spectroscopic

The generation of carbon dioxide (CO2) from Nordic fulvic acid (FA) solution in the presence of goethite (α-FeOOH) was observed in FA–goethite interaction experiments at 25–80 ℃. CO2 generation processes observed by gas cell infrared (IR) spectroscopy indicated two steps: the zeroth order slower CO2 generation from FA solution commonly occurring in the heating experiments of the FA in the presence and absence of goethite (activation energy: 16–19 kJ mol–1), and the first order faster CO2 generation from FA solution with goethite (activation energy: 14 kJ mol–1). This CO2 generation from FA is possibly related to redox reactions between FA and goethite. In situ attenuated total reflection infrared (ATR-IR) spectroscopic measurements indicated rapid increases with time in IR bands due to COOH and COO– of FA on the goethite surface. These are considered to be due to adsorption of FA on the goethite surface possibly driven by electrostatic attraction between the positively charged goethite surface and negatively charged deprotonated carboxylates (COO–) in FA. Changes in concentration of the FA adsorbed on the goethite surface were well reproduced by the second order reaction model giving an activation energy around 13 kJ mol–1. This process was faster than the CO2 generation and was not its rate-determining step. The CO2 generation from FA solution with goethite is faster than the experimental thermal decoloration of stable structures of Nordic FA in our previous report possibly due to partial degradations of redox-sensitive labile structures in FA.

scholarly journals Distinguishing active from quiescent disease in ANCA-associated vasculitis using attenuated total reflection Fourier-transform infrared spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam D. Morris ◽  
Camilo L. M. Morais ◽  
Kássio M. G. Lima ◽  
Daniel L. D. Freitas ◽  
Mark E. Brady ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Unmet Need ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Remission Induction ◽  
Disease Remission ◽  
Anca Associated Vasculitis ◽  
Active Disease ◽  
Quiescent Disease

AbstractThe current lack of a reliable biomarker of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis poses a significant clinical unmet need when determining relapsing or persisting disease. In this study, we demonstrate for the first time that attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy offers a novel and functional candidate biomarker, distinguishing active from quiescent disease with a high degree of accuracy. Paired blood and urine samples were collected within a single UK centre from patients with active disease, disease remission, disease controls and healthy controls. Three key biofluids were evaluated; plasma, serum and urine, with subsequent chemometric analysis and blind predictive model validation. Spectrochemical interrogation proved plasma to be the most conducive biofluid, with excellent separation between the two categories on PC2 direction (AUC 0.901) and 100% sensitivity (F-score 92.3%) for disease remission and 85.7% specificity (F-score 92.3%) for active disease on blind predictive modelling. This was independent of organ system involvement and current ANCA status, with similar findings observed on comparative analysis following successful remission-induction therapy (AUC > 0.9, 100% sensitivity for disease remission, F-score 75%). This promising technique is clinically translatable and warrants future larger study with longitudinal data, potentially aiding earlier intervention and individualisation of treatment.

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