Simultaneous determination of four oxidation parameters in frying canola oil by transmission FTIR spectroscopy without using any toxic organic solvents. Display omitted
•Simultaneous monitoring of ...TPC, CV, CD and CT in CLO during frying process at 180°C.•Four parameters analyzed by PLS chemometric method with an assay time less than 2min.•Transmission FT-IR spectroscopy was used as an analytical technique.•Proposed method is rapid, environmental friendly as compared to standard methods.•Proposed method is cheap and no sample preparation as compared to standard methods.
Transmission Fourier transform infrared (FTIR) spectroscopic method using 100μm KCl cell was applied for the determination of total polar compounds (TPC), carbonyl value (CV), conjugated diene (CD) and conjugated triene (CT) in canola oil (CLO) during potato chips frying at 180°C. The calibration models were developed for TPC, CV, CD and CT using partial least square (PLS) chemometric technique. Excellent regression coefficients (R2) and root mean square error of prediction values for TPC, CV, CD and CT were found to be 0.999, 0.992, 0.998 and 0.999 and 0.809, 0.690, 1.26 and 0.735, respectively. The developed calibration models were applied on samples of canola oil drawn during potato chips frying process. A linear relationship was obtained between CD and TPC with a good correlation of coefficient (R2=0.9816). Results of the study clearly indicated that transmission FTIR-PLS method could be used for quick and precise evaluation of oxidative changes during the frying process without using any organic solvent.
Because plant cell walls vary in their polysaccharide compositions and lignin contents, their monosaccharide compositions and lignin contents are often determined, but these analyses are time ...consuming and laborious. We therefore investigated Fourier transform infrared (FTIR) spectroscopy coupled with partial least squares (PLS) regression analysis as a way of rapidly predicting the monosaccharide compositions and lignin contents of the cell walls of compression wood (CW) and opposite wood (OW) of the gymnosperm
Pinus radiata
. The effects were investigated of sample moisture content (ambient or dry) and sample particle size (large particles, < 0.422 mm or small particles, < 0.178 mm) of milled wood on attenuated total reflectance (ATR) and transmission FTIR spectra, as well as the PLS-1 models and subsequent predictions. PLS-1 models were built using mixtures of CW and OW as the training set, to provide a linear range of monosaccharide compositions and lignin contents. Models were externally validated by predicting another set of wood mixtures before predicting CW and OW of a separate test set. Most of the monosaccharide amounts in the separate test set were best predicted by ATR spectroscopy of ambient large particles, achieving the lowest standard error values for the monosaccharides arabinose (0.36%), xylose (1.05%), galactose (1.79%), glucose (6.32%), and 4-
O
-methylglucuronic acid (0.20%). The results show the feasibility of using ATR spectroscopy of ambient large particles for the rapid prediction of monosaccharide compositions and lignin contents of plant cell walls.
Fourier transform infrared spectroscopy (FTIR) based methods for the determination of two anti-diabetic drugs, i.e., metformin HCl and glimepiride in tablet formulation are described. The methods ...involve the use of carefully prepared KBr discs with standards and samples of metformin HCl and glimepiride. FTIR spectra were acquired in the mid IR region. Extraction and pre concentration procedures were totally avoided. For quantification of metformin HCl, a prominent IR band appearing at fixed location height 3173 cm-1 with two point baseline between 3550-2850 cm-1 and for glimepiride IR band at fixed location height 1708 cm-1 with two point baseline between 1800-1600 cm-1 were selected for Beer's law calibrations. For metformin HCl, calibrations were developed using standards in the range between 0.300 mg to 3.100 mg whereas for glimepiride, calibrations were developed using standards in the range between 0.400 mg to 2.450 mg. Accuracy and reproducibility of proposed methods were evaluated and found to be satisfactory with excellent regression coefficients, acceptable recoveries and low standard deviations. The FTIR methods were successfully applied for the quantification of pharmaceutical tablets formulation containing metformin HCl and glimepiride as active substances and the results were found to be comparable with the quoted values.
In this study, a painted beehive panel from the collection of the Slovene Ethnographic Museum was examined with respect to its material composition with the aim to reveal the painting technique. Due ...to the state of degradation due to outdoor weathering (UV irradiation, rainfall, extreme temperature and humidity fluctuations), as well as past conservation interventions, the object represented a complex analytical challenge. We aimed for non-invasive techniques (FTIR in reflection mode, Raman spectroscopy and hyperspectral imaging in the range of 400–2500 nm); however, in order to explore paint layers, cross-sections were also analysed using Raman spectroscopy. FTIR spectroscopy in transmission mode and gas chromatography coupled to mass spectrometry were also used on sample fragments. Various original materials were identified such as pigments and binders. The surface coating applied during conservation interventions was also characterised. Additionally, organic compounds were found (oxalate, carboxylate), representing transformation products. The potential use of Prussian blue as a background paint layer is discussed.
In situ transmission FTIR spectra are measured during the electrochemical insertion of lithium into phospho-olivine FePO
4. The spectroelectrochemical cell consists of a composite FePO
4 cathode, a ...lithium metal anode, and an electrolyte of 1
M LiPF
6 in a 1:1 mixture of ethylene carbonate and diethyl carbonate (EC–DEC). Bands belonging to the electrolyte and cathode are identified in the infrared spectra of the
in situ cells. The antisymmetric PO
4
3− bending vibrations (ν
4) are used to monitor Li
+ insertion into FePO
4. Discharging produces spectral changes that are consistent with the formation of phospho-olivine LiFePO
4, yet the electrolyte bands are not affected by the discharging process. The
in situ infrared experiments confirm the two-phase mechanism for lithium insertion into FePO
4. Moreover, the experiments demonstrate the ability to collect
in situ transmission FTIR spectra of functioning electrode materials in lithium batteries. Unfortunately, lithium plating occurs on the optical window when the Li//FePO
4 half-cells are charged. The use of an intercalation anode such as graphite could alleviate this problem; however, this avenue of research is not explored in this study.
Stacked silicon nitride films for use in manufacturing of surface micromachined membranes were deposited using custom made plasma-enhanced chemical vapor deposition instrument with silane (SiH
4) and ...ammonia (NH
3) gas mixture as deposition precursor. Deposition conditions were adjusted by varying substrate temperature and SiH
4 to NH
3 flow ratio and temperature to obtain the required stress related and electrical properties of the membranes. Transmission Fourier transformed infrared spectroscopy and scanning electron microscopy were used to investigate the chemical composition and morphology of the stacked film components. An increase in the SiH
4 to NH
3 flow ratio and a decrease in temperature resulted in a silicon-rich silicon nitride film, as well as an increased silicon oxide concentration. To avoid underetch and sidewall defects, the plasma power density during the plasma etching was changed from 0.5 W/cm
2 during the etching of both top and bottom layers in a stacked film, to 1.0 W/cm
2 during the etching of the middle both silicon and silicon oxide rich film. This resulted in an improved overall stacked film sidewall quality and reduced the unwanted underetch.
Heterogeneous reactions of trace gases on the surface of particles in the atmosphere play a important role in the key atmospheric processes, and have been of increasingly interest in atmospheric ...sciences. However, these reactions, especially the corresponding detailed kinetics and mechanisms, have not been well understood, due to the deficiencies in the current experimental methods. The authors developed a novel experimental method for the study of heterogeneous reactions, based on transmission FTIR spectroscopy (T-FTIR), providing an understanding of the detailed physical chemistry that occurs on the surface of particles at the molecular level. In this method, the particles were evenly coated on a metal grid, and the gaseous reactant and the infrared beam were introduced to pass through the grid in the reactor. This method was used to explore the heterogeneous reaction of methacrolein (MAC) on the surface of SiO2 particles, a model heterogeneous reaction, under simulated atmospheric conditions. The result de
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