Identification Of Components In Mixtures Research Articles

Performance Improvement of Handheld Raman Spectrometer for Mixture Components Identification Using Fuzzy Membership and Sparse Non-Negative Least Squares.

Due to the advantages of low price and convenience for end-users to conduct field-based, in-situ analysis, handheld Raman spectrometers are widely used in the identification of mixture components. However, the spectra collected by handheld Raman spectrometer usually have serious peak overlapping and spectral distortion, resulting in difficulties in component identification in the mixture. A novel method for mixture components identification based on the handheld Raman spectrometer was proposed in this study. The wavelet transform and Voight curve fitting method were used to extract the feature parameters from each Raman spectral peak, including Raman shift, maximum intensity, and full width at half-maximum (FWHM), and the similarities between the mixture and each substance in the database were calculated by fuzzy membership function based on extracted feature parameters. Then, the possible substances in the mixture were preliminarily screened out as candidates according to the similarity. Finally, the Raman spectra of these candidates were used to fit the spectra of the mixture, and the fitting coefficients obtained by sparse non-negative least squares algorithm were employed to further determine the suspected substance in the mixture. The Raman spectra of 190 liquid mixture samples and 158 powder mixture samples were collected using a handheld Raman spectrometer and these spectra were used to validate the identification performance of the proposed method. The proposed method could achieve good identification accuracy for different mixture samples. It shows that the proposed method is an effective way for the component identification in mixture by using a handheld Raman spectrometer.

基于拉曼光谱的混合物组分识别方法

基于拉曼光谱的混合物组分识别方法

Qualitative and Quantitative Identification of Components in Mixture by Terahertz Spectroscopy

Typical methods for the analysis of mixture components include multiple linear regression, partial linear squares, and artificial neural network. However, these methods need large amount of samples and time to improve recognition accuracy. In this paper, based on the data obtained from terahertz spectroscopy, an identification method with less sample requirements and lower calculation time but higher accuracy is proposed. Based on the wavelet transform, baseline elimination, support vector regression, and loop iteration of samples, the specific substance in the mixture can be identified effectively. For example, seven substances that exist in brain glioma are chosen as the components of a mixture, where the key substances used for glioma diagnosis are set as the target substances and the spectra of mixtures with different mix proportions serve as training data. The average correlation coefficient of identification achieves 99.135% and the root-mean-square error is 0.40%. These results have profound implications for the eventual practical application of exact qualitative and quantitative identification of components in mixtures.

Simplification of electrospray mass spectra of Polysorbate 80 via cation transfer to carborane anions.

Mass spectrometric analysis of polymer mixtures via electrospray ionization can be complicated due the presence of multiple ion types, multiple charge states and multiple oligomeric distributions that complicate the detection and identification of mixture components. Polysorbate 80 (commercially known as Tween(®) 80) provides an example of this type, where the presence of polyoxyethylene sorbitan monooleate (PSO) byproducts gives rise to overlapping polymer distributions. It is desirable to simplify the spectrum in order to identify each component of what is inherently a complex mixture of fatty esters bound to different head groups. In this work, we show that gas-phase ion/ion reactions with carborane anions allow for the charge reduction of Tween(®) 80 peaks by selectively removing metal adducts bound to the synthetic polymer. The resulting singly charged spectrum reduces overlapping distributions and thus simplifies the identification of the components found in a Tween(®) 80 sample. The overall approach described here would likely lead to similar benefits in the analysis of other polymers that tend to ionize via metal ion adduction. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous chromatographic identification of a few components in mixtures based on a correlation between their absolute or relative retention times under different conditions

A correlation was established between the absolute and relative retention parameters of various compounds under different conditions of chromatographic analysis (isothermal and temperature programming conditions in gas chromatography or isocratic and gradient elution in high-performance liquid chromatography). This correlation is described by the linear regression equations t R (II) = = at R (I) + b with a high degree of accuracy. This property of chromatographic retention parameters allowed us not only to recalculate the values of these parameters determined under different conditions, but also to propose an algorithm for the simultaneous identification of a few components in complex mixtures with the use of published data on retention parameters found under other conditions (even presented as the drawings of chromatograms).

Analysis of a standard peptide mixture by capillary electrophoresis with mass spectrometry and with tandem mass spectrometry.

The combination of capillary electrophoresis with mass spectrometry allows efficient separation and identification of components in mixtures with greater specificity than can be obtained using capillary electrophoresis and ultra violet detection alone. For the mixture of peptides analysed in this application, molecular mass information was obtained on all of the components in the initial analysis. On-line capillary electrophoresis/tandem mass spectrometry was then used to generate amino acid sequence information for each of these peptides, at the pmole level, in the form of collision-induced production-ion spectra which were recorded only over the relevant time windows.

Environmental applications of combined multidimensional gas chromatography-infrared-mass spectrometry

This paper describes the development of a multidimensional gas chromatographic method for the analysis of environmentally interesting samples. In this study, sequential heartcutting across the entire chromatogram of two different paint or lacquer thinner samples was performed. Identification of mixture components was carried out using either computer spectral library search methods or by examination of the infrared and mass spectral data obtained from the analysis. After analyzing the heartcuts, it was determined that the number of identifiable components had increased from 12 to 60 for one thinner sample and from about 60 to 100 peaks for the other sample. These results demonstrate the analytical power of combining multidimensional gas chromatographic separation methods with the qualitative analysis capability of a modern infrared-mass spectral detection system. Some of the difficulties encountered in the present application of multidimensional gas chromatography are discussed.

Identification of mixture components in organic waste materials by carbon-13 nuclear magnetic resonance

Carbon-13 nuclear magnetic resonance (/sup 13/C NMR) is used to determine mixture component identities and relative concentrations in organic waste materials without prior separation. A quantitative /sup 13/C NMR spectrum provides the data used in an algorithm to extract subspectrum resonances specific to each mixture component. The subspectra are then subjected to reverse searches of either a /sup 13/C NMR simulated spectrum library or a /sup 13/C NMR chemical shift library. The quantitative /sup 13/C NMR mixture analysis algorithm is applied to seven wastes solvent mixtures procured from analytical and organic laboratories. The 34 subspectra comprised of NMR resonances above the 0.5% level in the mixtures yields 31 unambiguous identifications for the simulated library search and 27 unambiguous identifications from a search of the chemical shift library.

Solid-surface derivative room-temperature luminescence spectrometry of mixtures

Derivative solid-surface room-temperature fluorescence and phosphorescence were combined for the identification of components in binary and ternary mixtures of nanogram amounts of nitrogen heterocycles. Direct, and first and second derivative room-temperature phosphorescence excitation, room-temperature fluorescence and room-temperature phosphorescence spectra were used in the identification of the components in the mixtures by matching spectral wavelengths from mixtures with spectral wavelengths from standards. The criteria for matching wavelengths, subtracting background signals and obtaining derivative spectra at the 0.5-ng level are discussed.

Spectral data bases for chemical compound identification

The status of the large data bases for identifying unknown compounds by the use of X-ray diffraction, infrared spectrometry, Raman spectrometry and mass spectrometry is discussed. The paper reviews various spectra-encoding methods and library search techniques. The efficiency of identification of components in mixtures is evaluated from the point of view of information theory and miscellaneous methods toi separate the spectra of pure compounds are mentioned. Finally, the possibilities of interpretation of spectra not included in the spectra data base are summarized.

Oligosaccharides released from glycolipids by trifluoroacetolysis can be analyzed by gas chromatography-mass spectrometry

Carbohydrates are quantitatively released by trifluoroacetolysis of neutral glycosphingolipids that contain 4-sphingenine. During the reaction hydroxyl groups are O-trifluoroacetylated and N-acetyl hexosamines are transamidated to form N-trifluoroacetyl derivatives. Selective removal of O-trifluoroacetyl groups followed by permethylation produces derivatives with properties favorable for analysis by combined gas chromatography/mass spectrometry. Electron impact mass spectra of permethylated N-trifluoroacetylated oligosaccharide alditols are characterized by strong primary and secondary fragments in which a positive charge is localized on the N-trifluoroacetyl hexosamine residue. The method enables rapid separation and identification of components in mixtures of carbohydrate chains from glycosphingolipids containing up to six simple sugars.

System for identification of individual components in mixtures on the basis of shpol'skii spectra

System for identification of individual components in mixtures on the basis of shpol'skii spectra

Identification of components in mixtures by a mathematical analysis of mass spectral data

Mathematical techniques for the identification of components in mixtures from the mass spectra of a series of related mixtures are described. The approach is analogous to library search methods in that spectra from a reference collection are compared with a multidimensional unknown. Searches are conducted with a library file containing approximately 17000 mass spectra. Results for the analyses of several mixtures are reported, to illustrate the effectiveness of the method.