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Vibrational spectroscopy in supersonic jet expansions is a powerful tool to assess molecular aggregates in close to ideal conditions for the benchmarking of quantum chemical approaches. The low temperatures achieved as well as the absence of environment effects allow for a direct comparison between computed and experimental spectra. This provides potential benchmarking data which can be revisited to hone different computational techniques, and it allows for the critical analysis of procedures under the setting of a blind challenge. In the latter case, the final result is unknown to modellers, providing an unbiased testing opportunity for quantum chemical models. In this work, we present the spectroscopic and computational results for the first HyDRA blind challenge. The latter deals with the prediction of water donor stretching vibrations in monohydrates of organic molecules. This edition features a test set of 10 systems. Experimental water donor OH vibrational wavenumbers for the vacuum-isolated monohydrates of formaldehyde, tetrahydrofuran, pyridine, tetrahydrothiophene, trifluoroethanol, methyl lactate, dimethylimidazolidinone, cyclooctanone, trifluoroacetophenone and 1-phenylcyclohexane-cis-1,2-diol are provided. The results of the challenge show promising predictive properties in both purely quantum mechanical approaches as well as regression and other machine learning strategies.
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Modern analytical chemistry of industrial products is in need of rapid, robust, and cheap analytical methods to continuously monitor product quality parameters. For this reason, spectroscopic methods are often used to control the quality of industrial products in an on-line/in-line regime. Vibrational spectroscopy, including mid-infrared (MIR), Raman, and near-infrared (NIR), is one of the best ways to obtain information about the chemical structures and the quality coefficients of multicomponent mixtures. Together with chemometric algorithms and multivariate data analysis (MDA) methods, which were especially created for the analysis of complicated, noisy, and overlapping signals, NIR spectroscopy shows great results in terms of its accuracy, including classical prediction error, RMSEP. However, it is unclear whether the combined NIR + MDA methods are capable of dealing with much more complex interpolation or extrapolation problems that are inevitably present in real-world applications. In the current study, we try to make a rather general comparison of linear, such as partial least squares or projection to latent structures (PLS); "quasi-nonlinear", such as the polynomial version of PLS (Poly-PLS); and intrinsically non-linear, such as artificial neural networks (ANNs), support vector regression (SVR), and least-squares support vector machines (LS-SVM/LSSVM), regression methods in terms of their robustness. As a measure of robustness, we will try to estimate their accuracy when solving interpolation and extrapolation problems. Petroleum and biofuel (biodiesel) systems were chosen as representative examples of real-world samples. Six very different chemical systems that differed in complexity, composition, structure, and properties were studied; these systems were gasoline, ethanol-gasoline biofuel, diesel fuel, aromatic solutions of petroleum macromolecules, petroleum resins in benzene, and biodiesel. Eighteen different sample sets were used in total. General conclusions are made about the applicability of ANN- and SVM-based regression tools in the modern analytical chemistry. The effectiveness of different multivariate algorithms is different when going from classical accuracy to robustness. Neural networks, which are capable of producing very accurate results with respect to classical RMSEP, are not able to solve interpolation problems or, especially, extrapolation problems. The chemometric methods that are based on the support vector machine (SVM) ideology are capable of solving both classical regression and interpolation/extrapolation tasks.
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Técnicas de Química Analítica , Análise Multivariada , Espectroscopia de Luz Próxima ao Infravermelho , Biocombustíveis/análise , Gasolina/análiseRESUMO
Low-frequency, gas-phase vibrational (Raman) spectroscopy was used in conjunction with a jet-cooled technique and ab initio calculations to study the intrinsic thermodynamic properties of the free (gas-phase) amino acid--glycine (Gly, H(2)NCHRCOOH). The first experimental evaluation of the enthalpy differences between the Gly conformations in the vapor phase is presented. The enthalpy values were determined to be 0.33 ± 0.05 and 1.15 ± 0.07 kcal mol(-1) for the ccc and gtt rotamers, respectively; the corresponding relative entropy values were -2.86 ± 0.12 and -0.12 ± 0.16 cal mol(-1) K(-1), respectively. It was proven that the low-frequency Raman and infrared spectroscopy is capable of estimating intrinsic thermodynamic parameters of protein building blocks, such as intermolecular hydrogen bonds (ccc conformer) and rotation around one of the bonds (N-C, gtt conformer). The inaccuracy of the RRHO approximation to Gly conformers was experimentally confirmed. Benchmark data for quantum theory and molecular dynamics were provided.
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Glicina/química , Conformação Molecular , Termodinâmica , Gases/química , Modelos Químicos , Teoria Quântica , Espectrofotometria Infravermelho/métodos , Análise Espectral Raman/métodosRESUMO
In this study, we make a general comparison of the accuracy and robustness of five multivariate calibration models: partial least squares (PLS) regression or projection to latent structures, polynomial partial least squares (Poly-PLS) regression, artificial neural networks (ANNs), and two novel techniques based on support vector machines (SVMs) for multivariate data analysis: support vector regression (SVR) and least-squares support vector machines (LS-SVMs). The comparison is based on fourteen (14) different datasets: seven sets of gasoline data (density, benzene content, and fractional composition/boiling points), two sets of ethanol gasoline fuel data (density and ethanol content), one set of diesel fuel data (total sulfur content), three sets of petroleum (crude oil) macromolecules data (weight percentages of asphaltenes, resins, and paraffins), and one set of petroleum resins data (resins content). Vibrational (near-infrared, NIR) spectroscopic data are used to predict the properties and quality coefficients of gasoline, biofuel/biodiesel, diesel fuel, and other samples of interest. The four systems presented here range greatly in composition, properties, strength of intermolecular interactions (e.g., van der Waals forces, H-bonds), colloid structure, and phase behavior. Due to the high diversity of chemical systems studied, general conclusions about SVM regression methods can be made. We try to answer the following question: to what extent can SVM-based techniques replace ANN-based approaches in real-world (industrial/scientific) applications? The results show that both SVR and LS-SVM methods are comparable to ANNs in accuracy. Due to the much higher robustness of the former, the SVM-based approaches are recommended for practical (industrial) application. This has been shown to be especially true for complicated, highly nonlinear objects.
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Inteligência Artificial , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Algoritmos , Biocombustíveis/análise , Gasolina/análise , Análise dos Mínimos Quadrados , Redes Neurais de Computação , Análise de Componente Principal , SoftwareRESUMO
A multilayer feed-forward artificial neural network (MLP-ANN) with a single, hidden layer that contains a finite number of neurons can be regarded as a universal non-linear approximator. Today, the ANN method and linear regression (MLR) model are widely used for quantum chemistry (QC) data analysis (e.g., thermochemistry) to improve their accuracy (e.g., Gaussian G2-G4, B3LYP/B3-LYP, X1, or W1 theoretical methods). In this study, an alternative approach based on support vector machines (SVMs) is used, the least squares support vector machine (LS-SVM) regression. It has been applied to ab initio (first principle) and density functional theory (DFT) quantum chemistry data. So, QC + SVM methodology is an alternative to QC + ANN one. The task of the study was to estimate the Møller-Plesset (MPn) or DFT (B3LYP, BLYP, BMK) energies calculated with large basis sets (e.g., 6-311G(3df,3pd)) using smaller ones (6-311G, 6-311G*, 6-311G**) plus molecular descriptors. A molecular set (BRM-208) containing a total of 208 organic molecules was constructed and used for the LS-SVM training, cross-validation, and testing. MP2, MP3, MP4(DQ), MP4(SDQ), and MP4/MP4(SDTQ) ab initio methods were tested. Hartree-Fock (HF/SCF) results were also reported for comparison. Furthermore, constitutional (CD: total number of atoms and mole fractions of different atoms) and quantum-chemical (QD: HOMO-LUMO gap, dipole moment, average polarizability, and quadrupole moment) molecular descriptors were used for the building of the LS-SVM calibration model. Prediction accuracies (MADs) of 1.62 ± 0.51 and 0.85 ± 0.24 kcal mol(-1) (1 kcal mol(-1) = 4.184 kJ mol(-1)) were reached for SVM-based approximations of ab initio and DFT energies, respectively. The LS-SVM model was more accurate than the MLR model. A comparison with the artificial neural network approach shows that the accuracy of the LS-SVM method is similar to the accuracy of ANN. The extrapolation and interpolation results show that LS-SVM is superior by almost an order of magnitude over the ANN method in terms of the stability, generality, and robustness of the final model. The LS-SVM model needs a much smaller numbers of samples (a much smaller sample set) to make accurate prediction results. Potential energy surface (PES) approximations for molecular dynamics (MD) studies are discussed as a promising application for the LS-SVM calibration approach.
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Teoria Quântica , Algoritmos , Análise dos Mínimos Quadrados , Simulação de Dinâmica Molecular , Redes Neurais de ComputaçãoRESUMO
Heterogeneity is a characteristic feature of all populations of living organisms. Here we make an attempt to validate a single-cell mass spectrometric method for detection of changes in metabolite levels occurring in populations of unicellular organisms. Selected metabolites involved in central metabolism (ADP, ATP, GTP, and UDP-Glucose) could readily be detected in single cells of Closterium acerosum by means of negative-mode matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The analytical capabilities of this approach were characterized using standard compounds. The method was then used to study populations of individual cells with different levels of the chosen metabolites. With principal component analysis and support vector machine algorithms, it was possible to achieve a clear separation of individual C. acerosum cells in different metabolic states. This study demonstrates the suitability of mass spectrometric analysis of metabolites in single cells to measure cell-population heterogeneity.
Assuntos
Metaboloma , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Closterium/metabolismo , Análise de Componente PrincipalRESUMO
By gently bubbling nitrogen gas through beer, an effervescent beverage, both volatile and non-volatile compounds can be simultaneously sampled in the form of aerosol. This allows for fast (within seconds) fingerprinting by extractive electrospray ionization mass spectrometry (EESI-MS) in both negative and positive ion mode, without the need for any sample pre-treatment such as degassing and dilution. Trace analytes such as volatile esters (e.g., ethyl acetate and isoamyl acetate), free fatty acids (e.g., caproic acid, caprylic acid, and capric acid), semi/non-volatile organic/inorganic acids (e.g., lactic acid), and various amino acids, commonly present in beer at the low parts per million or at sub-ppm levels, were detected and identified based on tandem MS data. Furthermore, the appearance of solvent cluster ions in the mass spectra gives insight into the sampling and ionization mechanisms: aerosol droplets containing semi/non-volatile substances are thought to be generated via bubble bursting at the surface of the liquid; these neutral aerosol droplets then collide with the charged primary electrospray ionization droplets, followed by analyte extraction, desolvation, ionization, and MS detection. With principal component analysis, several beer samples were successfully differentiated. Therefore, the present study successfully extends the applicability of EESI-MS to the direct analysis of complex liquid samples with high gas content.
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The jet-cooled spontaneous Raman spectrum of an amino acid-alanine (Ala, 2-aminopropanoic acid; H(2)NCH(CH(3))COOH)-is reported. The low-frequency vibrational spectrum (below 500 cm(-1)) was recorded and assigned using quantum chemical data: ab initio (MP2) and DFT (BLYP, B3LYP, and PBE0). Band polarization measurements were used to confirm the vibrational assignments. The acquired medium resolution spectra (HWHM of approximately 4 cm(-1)) allow the different alanine conformations to be distinguished. Four alanine conformers were observed and identified: two previously reported by microwave spectroscopy studies and two that were previously unreported. A set of reasons for why these conformers eluded previous studies are discussed. Selective collisional relaxation processes in the jet (associated with low interconversion barriers between different alanine conformations) that depopulate the high-energy conformers were experimentally demonstrated.
Assuntos
Alanina/química , Gases/química , Análise Espectral Raman , Temperatura Baixa , Teoria Quântica , VibraçãoRESUMO
Optical spectroscopy of biological molecules in the gas phase has recently gained considerable attention, being able to provide complementary structural information in the absence of native matrix. Biomolecules can change their properties when brought into the gas phase, and so can chromophores associated with them. Understanding the photophysics of chromophore labels is central for the correct interpretation of experimental data. In this report, the structure and the optical properties of Rhodamine 19 (R19) in the gas phase were examined by a combination of Fourier-transform ion cyclotron resonance mass spectrometry and visible-light laser spectroscopy. While R19 in solution is found either in neutral (R19(n)) or protonated (R19+H(+)) forms, other structures can be generated in the gas phase, such as anions (R19-H(-)) and adducts with metal cations (R19+M(+)). Experimental evidence for the lactone structure of neutral gas-phase R19 is presented for the first time. The different properties of gas-phase compared to solution-phase R19 are discussed in view of structural analysis of labeled gas-phase biological molecules by optical spectroscopy.
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Rodaminas/química , Ânions/química , Cátions/química , Análise de Fourier , Gases/química , Espectrometria de Massas , Metais/química , Modelos Moleculares , Estrutura Molecular , Análise EspectralRESUMO
Visible light absorption and fluorescence of three positional isomers of protonated Rhodamine 19 (o-, m- and p-R19H(+)) were studied in solution and in the gas phase. In solution, strong solvatochromic effects lead to spectral shifts between rhodamine isomers. In contrast, in the gas phase, these species were found to exhibit very similar fluorescence, while pronounced differences were observed in the absorption spectra. The o-R19H(+) was found to have the largest Stokes shift in the gas phase (around 10 nm), suggesting that an intramolecular relaxation operates in the excited electronic state for this isomer. Several mechanisms for this relaxation are proposed, such as the change of the dihedral angle between the carboxyphenyl group and the xanthene chromophore or that between the carboxylic group and the phenyl ring.
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Tautomerism, a particular case of isomerism, plays an important role in modern organic chemistry, biochemistry, medicinal chemistry, pharmacology, and molecular biology. Inconsistency between results of complex energy computation methods Gn/CBS (G2, G3, CBS-4M, and CBS-QB3) and high-level ab initio/DFT ones (CCSD(T)/CBS, MP2/CBS, and B3LYP/aug-cc-pVTZ) is found. Gn/CBS methods provide a qualitatively different description of tautomeric (keto-enol) equilibrium in 2-substituted acetaldehydes. According to valence focal point analysis (FPA) based on CCSD(T)/aug-cc-pVTZ, MP3/aug-cc-pVQZ, and MP2/aug-cc-pV5Z energies, boryl substitution of acetaldehyde makes it an enol. In other words, enol was found to be the global minimum on the potential energy surface (PES) of C(2)H(5)BO. Gn/CBS methods predict the keto form to be the minimum. The relative energy of alkenol, CH(BH(2))=CH(OH), is calculated to be -1.67 +/- 0.82 kcal mol(-1) at CCSD(T)/CBS level of theory. Hydrogen shift effects are also calculated in two other 2-substituted acetaldehydes, namely, 3-oxopropanenitrile (C(3)H(3)NO) and ethanal (C(2)H(4)O), with a general formula of XH(2)C-CHO (X = BH(2), CN, and H). Electron density (charge) transfer between the C=C double bond and the free p orbital of the boron atom (B) in a boryl group (BH(2)) greatly stabilizes enol with respect to ketone, CH(2)(BH(2))-CHO. The first known stabilization of enol in an acetaldehyde derivative, without an intramolecular hydrogen bond (H-bond), questions the accuracy of complex energy computation methods for boron-containing molecules. The possible reasons and consequences of this finding are discussed.
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Acetaldeído/química , Alcenos/química , Boro/química , Teoria Quântica , Isomerismo , Modelos Moleculares , Conformação Molecular , Termodinâmica , VibraçãoRESUMO
The accuracy of quantum chemical treatment of biopolymers by means of density functional theory is brought into question in terms of intramolecular basis set superposition error (BSSE). Secondary structure forms--beta-strands (C5; fully extended conformation), repeated gamma-turns (C7), 3(10)-helices (C10), and alpha-helices (C13)--of homopolypeptides (polyglycine and polyalanine) are used as representative examples. The studied molecules include Ace(Gly)(5)NH(2), Ace(Gly)(10)NH(2), Ace(Ala)(5)NH(2), and Ace(Ala)(10)NH(2). The counterpoise correction procedure was found to produce reliable estimations for the BSSE values (other methods of BSSE correction are discussed). The calculations reported here used the B3LYP, PBE0 (PBE1PBE), and BMK density functionals with different basis sets [from 6-31G(d) to 6-311+G(3df,3pd)] to estimate the influence of basis set size on intramolecular BSSE. Calculation of BSSE was used to determine the deviation of the current results from the complete basis set limit. Intramolecular BSSE was found to be nonadditive with respect to biopolymer size, in contrast to claims in recent literature. The error, which is produced by a basis set superposition, was found to exceed 4 kcal mol(-1) when a medium-sized basis set was used. This indicates that this error has the same order of magnitude as the relative energy differences of secondary structure elements of biopolymers. This result makes all recent reports on the gas-phase stability of homopolypeptides and their analogs questionable.
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Biopolímeros/química , Teoria Quântica , Modelos Moleculares , Conformação Molecular , Peptídeos/químicaRESUMO
One of only two error sources in the solution of the electronic Schrodinger equation is addressed: The basis set convergence (incompleteness) error (BSIE). The results of ab initio (first principles) correlated methods, for which the Moller-Plesset second order perturbation theory (MP2) was chosen as an example, were extrapolated to the complete basis set (CBS) limit using a Dunning-type basis set series. Basis sets as large as cc-pV5Z and cc-pV6Z were used. A representative molecular set that included nitrogen (N(2)), acetylene (C(2)H(2)), ethylene (C(2)H(4)), carbon dioxide (CO(2)), water (H(2)O), ammonia (NH(3)), hydrogen cyanide (HCN), and ethanol (C(2)H(5)OH) molecules was used for the calculations. The intramolecular basis set superposition error (BSSE) was found to be correlated with BSIE, meaning that intramolecular BSSE can be used as a measure of basis set incompleteness. The BSIE dependence on BSSE could be qualitatively approximated (+/-25%) by a power-law dependence: BSIE = AxBSSE(p), where log(10)(A) = 1.45+/-0.21 and p = 1.27+/-0.09. This leads to the fact that CBS values at the MP2 theory level can be obtained using only one energy value and the corresponding intermolecular BSSE. The same power-law dependence was confirmed for all of the molecular systems studied. The universality of the BSIE versus BSSE dependence presented was checked using Pople-type basis sets. Even the results obtained with 6-311G, 6-311G(**), and 6-311G(2df,2pd) basis sets were found to be nicely described by the same (universal) power law. Benchmark studies of nitrogen and acetylene contraction (compaction) showed that BSIE can be decreased by up to 83% (at the cc-pVTZ level) using the CBS-BSSE strategy described. The presented BSIE versus BSSE dependence can greatly aid in obtaining CBS results for large molecular systems of chemical or biological interest.
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Conformation equilibrium in normal pentane (C(5)H(12)) was studied by the low-temperature gas-phase Raman spectroscopy method. A special retroreflecting multipass cell was constructed. Gas-phase (vapor) spectra were recorded in the temperature region of -130.3 to -23.1 degrees C and in the spectral range below 500 cm(-1). The peaks of trans-trans (399.0 cm(-1)), trans-gauche (328.9 cm(-1)), and gauche(+)-gauche(+) (267.1 cm(-1)) conformers (rotamers) of n-pentane were assigned using quantum chemistry data (MP2 and B3LYP methods with aug-cc-pVTZ basis set). The contour of each line was deconvoluted using ab initio data to obtain precise total integral intensity. The intensities at different temperatures were used to evaluate the enthalpy (energy) difference between trans-gauche and trans-trans (DeltaH(tg) = 618 +/- 6 cal/mol), and gauche(+)-gauche(+) and trans-trans (DeltaH(g+g+) = 940 +/- 20 cal/mol) conformers. Normal butane (n-butane) measurements under similar experimental conditions have been taken to understand the chain length influence. The C(4)H(10) enthalpy difference value has been evaluated (DeltaH(g) = 660 +/- 22 cal/mol). The results are compared with published experimental and theoretical data. The data presented here can be used as a reference for quantum chemistry calculations of conformation equilibrium in n-butane and n-pentane.
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The formic (methanoic) acid spectral range of 575-1150 cm(-1) has been studied by the gas-phase Raman spectroscopy method in a temperature region between 25 and 45 degrees C. A weak Raman-active vibration of polar (acyclic) HCOOH dimer (a-FAD) has been found at 864 +/- 2.1 cm(-1) and assigned using quantum chemistry data. The contours of the formic acid monomer (FAM) line at 1104 cm(-1) and the a-FAD line were deconvoluted using ab initio data to obtain precise total integral intensities. The temperature dependence of the intensity ratios was used to evaluate the thermodynamic parameters of the polar dimer. Its experimental dimerization enthalpy (DeltaH(a-FAD)) was found to be -8.6 +/- 0.2 kcal mol(-1). The entropy of dimerization has been evaluated using theoretical (MP2) Raman scattering activities. Its value (DeltaS(a-FAD)) is estimated as -36 +/- 2 cal mol(-1) K(-1). The results are compared with the published experimental data and calculations. The presented results can be used for molecular dynamics simulations, hydrogen bond energy estimation, and analysis of CH(2)O(2) vapor density measurements.
Assuntos
Formiatos/química , Termodinâmica , Simulação por Computador , Dimerização , Gases/química , Ligação de Hidrogênio , Isomerismo , Modelos Químicos , Teoria Quântica , Análise Espectral Raman/métodos , TemperaturaRESUMO
High-level ab initio electronic structure calculations, including extrapolations to the complete basis set (CBS) limit, were performed, and highly precise relative energies of five-member N-heterocycles were determined. Nitrogen-containing heterocycles studied included tautomers of tetrazole (CH(2)N(4)) and triazoles (C(2)H(3)N(3)). Valence focal-point analysis of 1H-tetrazole, 2H-tetrazole, 5H-tetrazole, 1H-1,2,3-triazole, 2H-1,2,3-triazole, 1H-1,2,4-triazole, and 4H-1,2,4-triazole and a number of transition state (TS) calculations were performed, using energy values determined by CCSD(T)/aug-cc-pVTZ, MP3/aug-cc-pVQZ, and MP2/aug-cc-pV5Z. An accuracy of 0.10-0.25 kcal mol(-1) (35-87 cm(-1)) was obtained for comparison of tautomer energy differences. Relative CCSD(T)/CBS energies of 2.07, 3.98, and 6.25 kcal mol(-1) for 1H-tetrazole, 1H-1,2,3-triazole, and 4H-1,2,4-triazole, respectively, were calculated. Use of electron correlation methods resulted in markedly different convergence behaviors for triazole and tetrazole tautomers. Similarly, differences in convergence were observed for TSs with respect to corresponding minima structures. It was confirmed that the MP2 method predicts an acyclic structure for 5H-tetrazole. The same was not observed for the corresponding TS geometry. Comparison with density functional theory (B3LYP) and model chemistry methods (CBS-4M and CBS-QB3) is reported.
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Artificial neural network (ANN) approach has been applied to estimate the density functional theory (DFT) energy with large basis set using lower-level energy values and molecular descriptors. A total of 208 different molecules were used for the ANN training, cross validation, and testing by applying BLYP, B3LYP, and BMK density functionals. Hartree-Fock results were reported for comparison. Furthermore, constitutional molecular descriptor (CD) and quantum-chemical molecular descriptor (QD) were used for building the calibration model. The neural network structure optimization, leading to four to five hidden neurons, was also carried out. The usage of several low-level energy values was found to greatly reduce the prediction error. An expected error, mean absolute deviation, for ANN approximation to DFT energies was 0.6+/-0.2 kcal mol(-1). In addition, the comparison of the different density functionals with the basis sets and the comparison of multiple linear regression results were also provided. The CDs were found to overcome limitation of the QD. Furthermore, the effective ANN model for DFT/6-311G(3df,3pd) and DFT/6-311G(2df,2pd) energy estimation was developed, and the benchmark results were provided.
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In this paper, an extra error source for high-quality ab initio calculation of conformation equilibrium in normal alkanes-intramolecular basis set superposition error (BSSE)-is discussed. Normal butane (n-butane) and normal hexane (n-hexane) are used as representative examples. Single-point energy difference and BSSE values of trans and gauche conformations for n-butane (and trans-trans-trans and gauche-gauche-gauche conformations for n-hexane) were calculated using popular electron correlation methods: The second-order Moller-Plesset (MP2), the fourth-order Moller-Plesset (MP4), and coupled cluster with single and double substitutions with noniterative triple excitation [CCSD(T)] levels of theory. Extrapolation to the complete basis set is applied. The difference between BSSE-corrected and uncorrected relative energy values ranges from approximately 100 cal/mol (in case of n-butane) to more than 1000 cal/mol (in case of n-hexane). The influence of basis set type (Pople or Dunning) and size [up to 6-311G(3df,3pd) and aug-cc-pVQZ] is discussed.
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In this paper we have tried to evaluate adsorption parameters of petroleum resins. Near infrared (NIR) spectroscopy is applied for resins bulk concentration evaluation during adsorption process. NIR experimental scheme and parameters are provided. NIR spectra range of 9000-13,000 cm(-1) is chosen. Quartz sand (0.2-0.8 mm fraction) is used as adsorbent; benzene is used as solvent. Different approaches of "NIR spectra-resins concentration" calibration model building are discussed. Partial least squares (PLS) regression method is used. Langmuir model is chosen for experimental data fitting. Combined usage of kinetic and isothermic data gives us ability to evaluate the maximal adsorbed mass density, the equilibrium constant of adsorption, and the rate constants of adsorption (and desorption). The rate constants of resins adsorption and desorption are found to be concentration independent.