Attenuated Total Reflection Fourier Transform Infrared Method Research Articles

Development of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Coupled with Multivariate Classification Chemometric Model for Routine Screening of Paracetamol, Ibuprofen, and Aspirin Adulteration in Herbal Products

Objective: The objective of this study is to develop and validate a routine screening test for the determination of three common antipyretic-analgesic synthetic drugs (paracetamol, ibuprofen, and aspirin) adulteration in herbal products using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) coupled with chemometric method. Method: ATR-FTIR spectra of sixteen testing sets of herbal product samples for pain and fever indications were used for multivariate chemometrics model construction. Linear Discriminant Analysis (LDA) was selected as a method for model construction with IBM SPSS for statistical analysis. Model development employed feature selection, such as the stepwise method for variable selection. The model with a high %correct classification and cross-validation was selected and was then validated with an independent testing data set with an auto-prediction test, confusion matrix, and Receiver Operating Characteristic (ROC) curve. To validate the developed test for routine use, the result from ATR-FTIR method was compared with the standard HPLC and TLC analyses used for adulteration screening. objective: Creating validated screening tools for herbal products adulterated with three common antipyretic-analgesic synthetic drugs (Paracetamol, Ibuprofen, and Aspirin) using ATR-FTIR couple with chemometric method Results: The selected model's overall %correct classification result was 97.7%, with a cross-validation of 93.8% rate in training set samples. External validation with an independent testing dataset gave an overall correct classification of 93.8%, with an area under the curve of ROC at 0.979. Comparative testing revealed that model performance was comparable with the HPLC and TLC methods, which routinely detect the presence of paracetamol, aspirin, and ibuprofen. The results of testing set samples classification were consistent with training set samples. Conclusion: Against the standard chromatographic methods, the multivariate chemometric model based on ATR-FTIR demonstrates comparable detection capability to determine adulteration of paracetamol, ibuprofen, and aspirin in herbal products.

ATR-FTIR and chemometric method for the detection of pig-based derivatives in food products - A review

The authentication of halal products is important, especially for Muslim communities. Based on the Islamic perspective, pig-based derivatives such as pork, lard, and gelatine are considered haram, which is an Arabic term for “forbidden”. Therefore, it is important to develop an analytical method for identifying and quantifying these compounds, which are sometimes found in some food products. The present work thus aimed to ascertain the potential of the attenuated total reflectance Fourier-transform infrared (ATR-FTIR) method for detecting pig-based derivatives in food products. ATR-FTIR spectrophotometry is recommended to be used to identify the presence of pig-based derivatives in some products, particularly processed food. In analytical chemistry, the method is generally used for the identification, characterisation, structure explanation, and monitoring of reactions. This analysis can be performed quickly, economically, easily, and does not require complicated sample preparation. ATR-FTIR can also be combined with principal component analysis (PCA), chemometric method, and multivariate partial least squares (PLS) calibration to accurately evaluate pig-based derivatives in beef meatballs. In combination with chemometric techniques, it can also provide the predictive and descriptive modelling in a combination with chemometric techniques by selecting the optimal frequency region. Furthermore, ATR-FTIR spectroscopy coupled with PLS and PCA chemometric regression models can be a potentially reliable, accurate, and precise method for determining pig-based derivatives in food.

Determination of metformin in fixed-dose combination tablets by ATR-FTIR spectroscopy

This study describes the determination of metformin in fixed-dose combination (FDC) tablets using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Metformin standard concentrations ranging from 10 to 100% w/w were prepared by diluting with potassium bromide (KBr). Prediction model was developed using partial least squares (PLS) based on the ATR-FTIR spectral region 1066.50–1052.47 cm −1 . The results of the model showed good linearity with a regression coefficient (R 2 ) of 0.9997. The root mean square error of calibration (RMSEC) was 0.447. Three commercial FDC drugs containing 500 mg metformin/tablet were quantified. The accuracy of the metformin quantification in the FDC tablets was 100% ± 2. The developed ATR-FTIR method is suitable for the routine determination of metformin in FDC tablets and other pharmaceutical formulations.

Superhydrophobic Breakdown of Nanostructured Surfaces Characterized in Situ Using ATR-FTIR.

In situ characterization of the underwater stability of superhydrophobic micro- and nanostructured surfaces is important for the development of self-cleaning and antifouling materials. In this work, we demonstrate a novel attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy-based method for large-area wetting characterization of silicon nanopillars. When air is present in between the structures, as is characteristic of the Cassie-Baxter state, the relative intensities of the water bands in the absorption spectrum change because of the wavelength-dependent attenuation of the evanescent wave. This phenomenon enables unambiguous identification of the wetting state and assessment of liquid impalement. Using mixtures of isopropanol and water with different concentrations, the breakdown of superhydrophobic states and the wetting hysteresis effects are systematically studied on uniform arrays of silicon nanopillars. A transition from the Cassie-Baxter to Wenzel state is observed when the isopropanol concentration exceeds 2.8 mol %, corresponding to a critical surface tension of 39 mN/m. Spontaneous dewetting does not occur upon decreasing the isopropanol concentration, and pure water can be obtained in a stable Wenzel state on the originally superhydrophobic substrates. The developed ATR-FTIR method can be promising for real-time monitoring of the wetting kinetics on nanostructured surfaces.

Determination of trans Fat in Selected Fast Food Products and Hydrogenated Fats of India Using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy.

This paper reports the application of a simple and rapid method for the determination of trans fatty acid (TFA) content in some of the selected Indian fast food products and hydrogenated fats using Fourier transform infrared (FTIR) spectroscopy in conjunction with second derivative procedure. FTIR spectroscopy has been successfully applied to trans measurement using the absorbance bands at or near 966 cm-1 in the FTIR spectra. It was found from the analysis that TFA content of fast food product was ranging from 1.57% to 3.83% of the total fat while for hydrogenated fats, comparatively large quantity of TFA was detected in the range of 3.31% to 4.73%. Since GC-FID is most widely used method for the determination of fatty acid (FA) composition, this method was used for the sake of comparison. Value of regression coefficient was found very close to one (0.99503) with standard deviation of 0.10247 showing a good agreement between GC-FID and proposed ATR-FTIR method.

Abstract 3909: Interactions of glioma cells with chlorotoxin: an ATR-FTIR spectroscopy study

Abstract Chlorotoxin is a scorpion-derived peptide that preferentially binds to tumor cells of neuroectodermal origin, like glioma, but not to normal non-transformed cells. We have previously reported the development of a targeted nanodelivery system using chlorotoxin. Chlorotoxin has been studied as an imaging and targeting agent for drug and radioisotope delivery, but the mechanism of interaction of chlorotoxin with cancer cells has not been well understood and it needs to be further evaluated in order to optimize its use as a targeting compound for cancer cells. In this study, we used U87 human glioma cell line to evaluate the binding kinetics of chlorotoxin by Attenuated Total Reflection Fourier Transform Infra-Red (ATR-FTIR) spectroscopy. As a sensitive and label free technique, ATR-FTIR is a powerful diagnostic tool for the comparison of cancer cells with normal cells. First, we characterized the signature spectra of chlorotoxin and U87 cells by assigning and evaluating the infrared absorption bands and their second derivatives. Next, we studied the spectral differences between U87 cells incubated with and without chlorotoxin for incremental time periods ranging from 15 minutes to 24 hours. We also examined the metabolic changes in U87 cells induced with chlorotoxin at different incubation time points by measuring the ratios of integrated areas corresponding to different chemical conformations of proteins, lipids, carbohydrates, and nucleic acids. Our results revealed spectral changes in U87 cells at different stages of incubation with chlorotoxin. The most notable change occurred after 30 minutes of incubation, where the band assigned to CH3 bending of lipid membranes shifted from 1456 cm-1 to 1450 cm-1. Consequently, a new shoulder appeared at wavenumber of 1466 cm-1 assigned to CH2 bending of lipid membranes for U87 cells treated with chlorotoxin. These changes indicate a direct interaction due to the presence of a molecular binding site between chlorotoxin and the lipids of the cell membrane. Another significant alternation occurred after 1 hour of incubation of U87 cells with chlorotoxin in the spectral region assigned for nucleic acids. This interaction included a large upshift of the band at 1036 cm-1 to 1051 cm-1 assigned to C-O stretching vibrations of ribose ring in RNA due to the hydrogen bonding with chlorotoxin. These findings suggest at least two different interactions of chlorotoxin with U87 human glioma cells that can be further explored for improving chlorotoxin containing drug delivery systems. We are currently using the ATR-FTIR method to conduct control experiments by measuring possible interactions of chlorotoxin with normal human astrocytes. Citation Format: Rana Falahat, Marzenna Wiranowska, Ryan Toomey, Norma Alcantar. Interactions of glioma cells with chlorotoxin: an ATR-FTIR spectroscopy study. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3909.

Reaction Monitoring of in Situ Formation of Poly(sodium acrylate)-Based Nanocomposites Using ATR-FTIR Spectroscopy

The in situ formation of poly(sodium acrylate)-based nanocomposites was monitored in-line using an attenuated total reflectance/Fourier transform infrared (ATR-FTIR) spectroscopic probe. Results were compared with conversion measurements using an off-line gravimetric method. A multivariate statistical data treatment based on the online data for the nanocomposite containing 0.5 wt % of nanosilver was used to calibrate the ATR-FTIR spectroscopic probe. The ATR-FTIR method was shown to be reliable based on 95% confidence intervals for monitoring the production of polymers synthesized in the presence of different amounts of nanosilver over the full range of monomer conversion.

Analysis of Oil Content in Ultrafiltered Water Based on Oil Emulsion using Fourier Transform Infrared Spectroscopy (FTIR)

The quantitative analysis is a simple and fast method that has been developed to analyse the oil content in the permeate of ultrafiltration process. Measurements of concentration were done on standard palm oil solution within 0.05–7.00 wt. %, followed by verification of permeate content to validate the calibration model. The measurement was based on simple Beer’s Laws method to determine the concentration of oil in the permeated water. The standard oil solution was analysed using Attenuated Total Reflectance– Fourier Transform Infrared (ATR-FTIR) to obtain the spectrum of triglycerides group, which are the principal component that exists in fats and oils. The absorption wavelength was found to be within 1789.62 cm-1 and 1697.53 cm-1. The selected region will be used to quantify the standard oil concentration. Regression coefficient (R2) for the calibration model and validation was 0.99267 and 0.9913, respectively indicating excellent oil concentration determination. These results showed that all the measurements were in the range of calibration curve which shows a facile method is suitable for the oil determination in the permeate water samples. The ATR-FTIR method was compared with turbidity method, thus ATR-FTIR method was preferred and reliable to be used in determining of oil concentration.

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy of a single endothelial cell

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with the use of a slide-on germanium accessory followed by chemometric analysis allowed for providing meaningful information about the biochemical composition of a single endothelial cell. In this work, the methodology of the ATR-FTIR measurements of dried cells and dried cells immersed in water solution is presented. The contact of the cell and Ge crystal was set up manually and monitored through the integration of the amide I band. Additionally, the cell imaging in transreflection mode was tested, but the spectral differences between sub-cellular structures were not prominent in the registered spectra. It has been shown that the ATR-FTIR method gives better results due to the increased spatial resolution and S/R ratio as well as small contribution of the optical artifacts.

Attenuated total reflection Fourier transform infrared studies of redox changes in bovine cytochrome c oxidase: resolution of the redox Fourier transform infrared difference spectrum of heme a(3).

Attenuated total reflection Fourier transform infrared (ATR-FTIR) difference spectroscopy has been performed on samples of bovine cytochrome c oxidase that have been deposited as a thin film on the surface of a silicon microprism. The technique has several advantages over transmission methods in terms of amount of material required, the time required to reach sufficient optical stability, and the range of reactants that can be repetitively added and removed. The ATR-FTIR method has been used to record redox difference spectra of cytochrome c oxidase in the unligated and cyanide-ligated states. By subtraction of the spectra, the redox FTIR difference spectrum of heme a(3) can be resolved from those of the other metal centers. This difference spectrum is compared with available vibrational and Raman data on homologous oxidases and on heme A model compounds.

Rapid determination of total Trans fat content by attenuated total reflection infrared spectroscopy: An international collaborative study

Interest in trans fat labeling has prompted efforts to develop new, more efficient methods for rapidly and accurately determining trans fat content of foods. A novel and rapid (5 min) attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic procedure was recently developed and applied to food products. This procedure was voted official method AOCS Cd 14d-99 by the American Oil Chemists' Society in 1999 after testing in a 12 laboratory international collaborative study. The results of the study are described in this paper. Analytical ATR-FTIR results exhibited high accuracy in the range 5-40% trans; results tended to have <2% high bias relative to the gravimetrically determined values. The precision of this internal reflection method was found to be superior to the precision of transmission infrared official methods. It is recommended that the applicability of the ATR-FTIR method be limited to trans levels of >5% (as percent of total fat).

In situ Measurements of Tetraphenylboron Degradation Kinetics on Clay Mineral Surfaces by IR

An attenuated total reflectance Fourier transform infrared (ATR-IR) spectroscopic method has been developed to quantitatively measure, in situ, the surface-facilitated degradation of tetraphenylboron (TPB) in fully aquated clay pastes. Two pathways for degradation of TPB could be studied both independently and simultaneously. Surface-facilitated oxidation of TPB to diphenylboric acid (DPBA) at Lewis acid sites on clay mineral surfaces was investigated on three members of the smectite family of clays. No degradation of TPB occurred on hectorite, which contains no structural Fe. TPB degraded to DPBA on montmorillonite and nontronite. A color change in nontronite indicated the production of mixed valence Fe[sup 3+]-O-Fe[sup 2+] states and clearly demonstrates the reduction of structural iron during the course of the reaction. The degradation of TPB to triphenylboron (TriPB) at Bronsted acid sites could also be measured on aluminum-saturated clays either independently on hectorite or simultaneously to the Lewis acid reaction on montmorillonite by the ATR-IR method. First-order rate models are developed for both reactions and describe the data well. 28 refs., 4 figs., 1 tab.