Summary: An attenuated total reflection FT‐IR spectroscopic study of the hydrogen bonding, molecular orientation, and crystalline phase transitions in polyamide 6 (PA6)/clay nanocomposite (PA6CN) fibers is proposed. The nanoscale dispersed clay layers lowered the degree of order of hydrogen bonding, affected little the hydrogen bonding strength, and increased the degree of orientation of both γ crystalline and overall domains. A partial γ to α phase transition appeared with time.
Schematic representation of the attenuated total reflection FT‐IR dichroism measurements. 相似文献
There is a high demand for rapid determination of fipronil in pesticide preparations because it has been restricted and even prohibited in many countries. An infrared-based methodology was developed for this analyte in acetamiprid formulations by attenuated total reflectance mid-infrared spectroscopy. The quantitative calibration models of fipronil were established by partial least squares regression. The determination coefficients (R2) of the model were above 0.99 while both the root mean square error of prediction and root mean square error of calibration were below 0.0011, which showed the partial least squares model accurately predicted fipronil concentrations in acetamiprid. The accuracy was further demonstrated by comparison with another two models' results of low (<1.0%, w/w) and high concentration sample sets (1.0%–4.5%, w/w). These results demonstrate the potential of infrared spectroscopy to quickly detect fipronil in acetamiprid. 相似文献
The present paper cover a measurement system combining reflection spectroscopy photocurrent spectroscopy and photocapacitance spectroscopy, and a measurement system for time resloved reflection and transmission spectroscopy in the ultraviolet-visible spectral region built in suit to characterize electrochemistrical processes. A differential or subtractive spectral method with recpect to an electrode potential change has been adopted in both systems in order to obtain a high S/N ratio. 相似文献
A spectroscopic method based on attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy has been developed
for reagent-free analysis of blood and urine constituents in the clinical laboratory and for point-of-care-applications. Blood
plasma, whole blood, and urine were analyzed without any sample preparation, such as drying, concentration, or enrichment.
Sample volumes as small as 5 μL (a single drop of blood) can be used. Mathematical models, including partial least-squares
regression, were used to construct a prediction model which can calculate the concentration of albumin, cholesterol, glucose,
total protein, urea, and triglycerides in whole blood or blood plasma samples and the concentration of urea, uric acid, phosphate
and creatinine in urine samples. The absolute precision and reproducibility of the prediction reached is sufficient for routine
clinical analysis and is only limited by the precision of the reference analysis used for calibration. This was achieved by
use of a large number of calibration samples (approx. 400 for blood samples and approx. 100 for urine samples) carefully selected
for physiological and pathological range and for specific disease profiles. 相似文献
The aim of the study was the non-destructive and rapid evaluation of the phytotoxicity of different concentrations of mercury (0.2, 0.4, 0.6, 0.8, and 1?mM) on the biochemical profile of wheat seedlings using attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy in combination with principal component analysis. Infrared spectra of the leaves of control and mercury-treated wheat seedlings were recorded in the spectral region from 4000 to 485?cm?1. The preprocessing of the recorded spectra by second derivation enhanced the specificity of the infrared bands. The area of the bands estimated by curve fitting was used for the relative quantitative estimation of the biochemical changes involved. The principal component analysis of the acquired spectral measurements discriminated between the biochemicals of the control and mercury-treated wheat seedlings. The result showed that mercury (0.2–1?mM) significantly enhanced the content of the cell wall polysaccharides, amino acids, β-sheet component of proteins, and lipids in the leaves accompanied by reduction in the amount of α-helix. The change in β-sheet/α-helix ratio indicated mercury induced structural changes in the secondary structure of proteins. The increase in the levels of methylene bands and carboxyl bands indicates changes in lipid configuration and peroxidative damage caused by mercury. The results of this study demonstrate the potential of ATR–FTIR in combination with principal component analysis as an environmental monitoring tool for the identification of plant populations affected by environmental factors like heavy metal stress prior to the appearance of visual signs of toxicity. 相似文献
The aim of this study is to evaluate the biochemical changes in the leaves of wheat seedlings exposed to gold nanoparticles (AuNPs) nondestructively and rapidly using attenuated total reflectance Fourier transform infrared spectroscopy and laser-induced fluorescence. The 18?nm size gold nanoparticles are synthesized by citrate reduction. For analyzing the effect of gold nanoparticles on wheat seedlings, the treatment of gold nanoparticles was applied to the seedlings through roots and following the spectroscopic measurement of biochemical signatures. The laser-induced fluorescence measurement has been performed to access the effect of gold nanoparticles on the chlorophyll concentration of wheat seedlings. The decrease in the fluorescence intensity and the fluorescence intensity ratio on the treatment of gold nanoparticles indicates increase in the concentration of chlorophyll in the leaves of wheat seedlings. The attenuated total reflectance Fourier transform infrarred spectroscopy in combination with principal component analysis has been used to visualize the biochemical changes in the cellulose, hemicellulose, pectin, lignin, amino acids, proteins, and lipid of the leaves of wheat seedlings by recording infrared spectra in the region from 4000 to 400?cm?1. Principal component analysis applied to the preprocessed infrared data clearly distinguishes the spectral variability between control and gold nanoparticle treated seedlings. The study shows that exposure of gold nanoparticles increases the concentrations of cellulose, hemicelluloses, pectin, and lignin in the leaves of wheat seedlings. The increase in these chemicals indicates the modulation of cell walls of the wheat seedlings by the gold nanoparticle treatment. The exposure to gold nanoparticles also enhances the expression of lipid and proteins in the leaves of wheat seedlings. 相似文献
It is demonstrated for the first time that the principal constituents of a shampoo as well as of a liquid soap -three surfactants and water- can be determined directly, simultaneously and quickly in undiluted samples by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy in the middle infrared region, despite the broad absorption bands of the solvent. Two of the surfactants, sodium lauryl ether sulfate (SLES) and cocoamidopropyl betaine (CAPB), are common to both formulations; alkylpolyglucoside (APG) is the third surfactant of the liquid soap and cocodiethanolamide (CDEA), the corresponding ingredient of the shampoo. Absorbance data of the undiluted samples and of the calibration standards was collected in the middle infrared region of the spectrum (800-1600 and 1900-3000 cm−1). Two methods of multivariate quantification were compared: classical least squares (CLS), where absorbance data measured at 200 wavenumbers was processed, and inverse least squares (ILS), where data at 10 selected wavenumbers was analyzed. A spectra normalization procedure, based on a dominating water band, was examined. Twenty-seven standard mixtures were used for each application, consisting of all combinations at three concentration levels of each surfactant, respectively the lower limit, the expected value and the upper limit accepted in quality control. By favoring wavenumbers where absorption bands of the minor components (APG in the liquid soap and CDEA in the shampoo) are more intense, good results were obtained for 18 simulated samples of shampoo and 18 samples of liquid soap, no matter if calculations were made by CLS or ILS. The relative errors for water (major component, 84-88%) and SLES (7-10%) were always below 2%; for CAPB (2-4%), APG (<2%) and CDEA (<2%), they occasionally reached 5% of the component, an uncertainty of less than 0.07% in terms of the sample weight. 相似文献
