Search results for "Chemometric"
showing 10 items of 109 documents
Quantitative Analysis, Infrared
2000
In this article, after reviewing the different mathematical methods used in quantification we will describe and discuss their respective advantages and inconveniences. First of all, different examples of applications of infrared (IR) spectroscopy, used with or without other analytical chemistry methods, will be presented. Some examples of direct quantitative analysis in food analysis will be reviewed: lipids (measurement of unsaturation degrees, lipids determination), carbohydrates, proteins (secondary structures, quantitative analysis). We will also focus on original examples of the use of IR spectroscopy combined with enzymes. Secondly, some examples of Fourier transform infrared (FTIR) a…
Univariate method for background correction in liquid chromatography–Fourier transform infrared spectrometry
2007
An univariate method is proposed for background correction in on-line gradient liquid chromatography-Fourier transform infrared (LC-FTIR) spectrometry using acetonitrile:water as mobile phase components. The method is based on the calculation of the ratio of absorbances (AR) at two characteristic wavenumbers for each spectrum. This parameter is subsequently used to locate the most appropriated eluent spectrum within a reference spectra matrix (RSM) to be subtracted from each spectrum included in the sample chromatogram. To correct minor changes in eluent spectra intensity during the elution of analytes, a correction factor (Kf), defined as the ratio of the absorbance of the sample and the s…
Origin based classification of crude oils by infrared spectrometry and chemometrics
2019
Abstract Crude oil samples from different Iranian petrol resources in both, raw and mixture forms have been characterized by attenuated total reflectance mid infrared spectroscopy. Obtained spectra were classified by chemometric techniques to propose a method for geological based classification of crude oil samples. Totally 251 samples from 7 petrol fields and 3 mixtures were analyzed. Mean centering and principal component analysis (PCA) supported – leverage value based outlier detection were used as preprocessing approaches. PCA, cluster analysis and soft independent modeling of class analogy (SIMCA) were utilized to classify the spectra. Obtained results confirmed that SIMCA is a robust …
Limits of multi-linear gradient optimisation in reversed-phase liquid chromatography
2005
Abstract The concept of limiting peak purity was applied to quantify the degree of completion of the separation capability of a chromatographic system using multi-linear gradients. The objective was to check whether the complexity of a gradient program deserves be increased to enhance resolution by inserting more linear segments, or on the contrary, no significant improvements can be expected under more complex gradients. A set of 19 isoindole derivatives of primary amino acids was selected to test the performance of isocratic, single linear and multi-linear gradients. Accurate simulated chromatograms were obtained via numerical integration of the general equation of gradient elution, using…
Sweeteners determination in table top formulations using FT-Raman spectrometry and chemometric analysis
2004
Abstract A partial least squares (PLS) Fourier transform Raman spectrometry procedure based on the measurement of solid samples contained inside standard glass vials, has been developed for direct and reagent-free determination of sodium saccharin and sodium cyclamate in table top sweeteners. A classical 22 design for standards was used for calibration, but this system provides accuracy errors higher than 13% w/w for the analysis of samples containing glucose monohydrate. So, an extended model incorporating glucose monohydrate (23 standards) was assayed for the determination of sodium saccharin and sodium cyclamate in all the samples. Mean centering spectra data pre-treatment has been emplo…
Identification of Key Gin Aroma Compounds
2014
Potential impact aroma compounds of gin have been identified using Gas Chromatogry Olfactometry Mass-Spectrometry (GC-O-MS). In order to select some of them for a recombination study, we developed a specific procedure. Instead of only choosing the compounds on criteria such as their odor quality or their odor activity values, we also used physico-chemical parameters and information on their botanical origin. Data were organized in blocks homogeneous in terms of parameter type. Different statistical treatments were used in order to classify the compounds either by analyzing the parameters altogether or separately block by block.
Prediction of soil texture distributions using VNIR-SWIR reflectance spectroscopy
2013
Abstract Reflectance spectroscopy provides an alternate method to non-destructively characterize key soil properties. Different approaches, including chemometrics techniques or specific absorption features, have been proposed to estimate soil properties from visible and near-infrared (VNIR, 400-1200 nm) and shortwave infrared (SWIR, 1200-2500 nm) reflectance domains. The main goal of this study was to test the performance of two distinct methods for soil texture estimation by VNIR-SWIR reflectance measurements: i) the Continuum Removal (CR) technique that was used to correlate specific spectral absorption features with clay, silt and sand content, and ii) the Partial Least-Squares Regressio…
Vibrational spectroscopy provides a green tool for multi-component analysis
2010
Abstract Based on the literature published in the past decade, we focus on the possibilities offered by vibrational-spectroscopy-based techniques to make multi-component analysis of samples independently of their physical state. We discuss the main chemometric tools proposed for developing calibration models and solving problems derived from spectroscopic non-idealities (e.g., highly overlapped spectral bands or the presence of spectral non-linearity), and the benefits provided by vibrational-spectroscopy-based multi-component analysis in industry. Our main objective is to show that vibrational spectroscopy provides fast analytical methods that enable non-destructive analysis and permits, i…
Mass Spectrometry in Food Quality and Safety
2015
Abstract In recent years, mass spectrometry has gained a wide recognition as a selective and fast technique for the analysis and assessment of a wide range of food products. The state of the art in the determination of safety and quality of food is presented to illustrate the capability of this technique for classification and grading, defect and disease detection, distribution and visualization of chemical attributes, and evaluations of overall quality of meat, fish, fruits, vegetables, and other food products. The features of mass spectrometry for each category were summarized in the aspects of the investigated quality and safety attributes, the used systems (triple quadrupole, quadrupole…
Ligand-based discovery of novel trypanosomicidal drug-like compounds: In silico identification and experimental support
2010
Abstract Two-dimensional bond-based linear indices and linear discriminant analysis are used in this report to perform a quantitative structure–activity relationship study to identify new trypanosomicidal compounds. A database with 143 anti-trypanosomal and 297 compounds having other clinical uses, are utilized to develop the theoretical models. The best discriminant models computed using bond-based linear indices provides accuracies greater than 90 for both training and test sets. Our models identify as anti-trypanosomals five out of nine compounds of a set of already-synthesized substances. The in vitro anti-trypanosomal activity of this set against epimastigote forms of Trypanosoma cruzi…