Search for: multivariate-curve-resolution-alternating-least-squares
Total 21 records
Detecting intermediate particles in the growth of colloidal zinc oxide nanoparticles in different chemical routes using MCR-ALS, Article Journal of Chemometrics ; Volume 27, Issue 10 , 2013 , Pages 353-358 ; 08869383 (ISSN) ; Jalali Heravi, M ; Kafrashi, F ; Sharif University of Technology
Zinc oxide (ZnO) nanoparticles have been used in a wide-ranging of applications such as transparent UV protection, light emitting diodes, sensors and photovoltaic cells. Many applications of ZnO nanoparticles could be improved by changing the particle size, shape and morphology. Therefore, studying the mechanism of shape evolution is crucial for size and shape controlled synthesis of nanocrystaline ZnO particles. As an alternative to sophisticated techniques such as transmission electron microscopy (TEM) and X-ray powder diffraction (XRD), commonly used for studying nanoparticles evolution, we herein employed UV/Vis spectroscopy for monitoring the evolution process of the ZnO nanocrystals...
Comprehensive two-dimensional gas chromatography (GC×GC) retention time shift correction and modeling using bilinear peak alignment, correlation optimized shifting and multivariate curve resolution, Article Chemometrics and Intelligent Laboratory Systems ; Volume 117 , 2012 , Pages 80-91 ; 01697439 (ISSN) ; Jalali Heravi, M ; Tauler, R ; Sharif University of Technology
A combination of peak alignment methods and multivariate curve resolution (MCR) is proposed for handling retention time shifts and modeling of comprehensive two-dimensional gas chromatographic (GC × GC) data in the case of univariate detection systems such as in flame ionization detection (FID) or in total ion current mass spectrometry (TIC-MS) detection. A new bilinear peak alignment (BPA) method, based on MCR, is first proposed to correct for progressive within run retention time shifts in GC × GC due to temperature programming effects on second chromatographic dimension. The performance of the proposed peak alignment method is compared to that of the correlation optimized warping (COW)...
Article TrAC - Trends in Analytical Chemistry ; Volume 31 , 2012 , Pages 134-143 ; 01659936 (ISSN) ; Jalali Heravi, M ; Tauler, R ; Sharif University of Technology
In this article, we examine Independent Component Analysis (ICA) and the concept of Mutual information (MI) as a quantitative measure of independence from the point of view of analytical chemistry. We compare results obtained by different ICA methods with results obtained by Multivariate Curve Resolution Alternating Least Squares (MCR-ALS). These results have shown that, when non-negativity constraints are applied, values of MI increase considerably and the resolved components cannot anymore be considered to be independent (i.e. they can only be considered to be the " least dependent" components). MI values of profiles resolved by MCR-ALS and ICA did not differ significantly when...
Thorough analysis of Iranian spearmint essential oil: Combination of chemometrics and gas chromatography-mass spectrometry, Article Analytical Methods ; Vol. 6, Issue. 17 , 2014 , Pages 6753-6759 ; ISSN: 17599660 ; Moazeni-Pourasil, R. S ; Sereshti, H ; Sharif University of Technology
The components of Iranian spearmint essential oil were identified and quantified using gas chromatography-mass spectrometry (GC-MS) combined with chemometric tools. A multivariate curve resolution (MCR) approach was used to overcome the problems of background, baseline offset and overlapping/embedded peaks in GC-MS. The peaks were resolved using heuristic evolving latent projection (HELP) and multivariate curve resolution-alternating least squares (MCR-ALS) techniques. A new pure variable selection method named multivariate curve resolution-objective function equal to zero (MCR-FEQZ) is introduced and was applied in this work. The performance of this technique was evaluated and confirmed...
Colorimetric detection of glutathione based on transverse overgrowth of high aspect ratio gold nanorods investigated by MCR-ALS, Article RSC Advances ; Volume 5, Issue 101 , 2015 , Pages 82906-82915 ; 20462069 (ISSN) ; Shadabipour, P ; Hormozi-Nezhad, M. R ; Sharif University of Technology
Royal Society of Chemistry 2015
In this paper, we present a simple platform for colorimetric detection of glutathione using gold nanorods (AR ∼ 6.5 ± 0.2) as a plasmonic sensor. The functional mechanism of the sensor is based on shifts of longitudinal plasmon resonance during selective transverse overgrowth induced by preferential binding of glutathione at the nanorod tips. Under the optimum conditions, a calibration curve showed two linear regimes at the range of 50 nM to 20 μM of glutathione with a detection limit as low as 40 nM. The nanosensor maintains relatively high selectivity for determination of glutathione in the presence of several other amino acids. However, cysteine at similar concentration levels strongly...
Comparative study of partial least squares and multivariate curve resolution for simultaneous spectrophotometric determination of pharmaceuticals in environmental samples, Article RSC Advances ; Volume 5, Issue 86 , Aug , 2015 , Pages 70017-70024 ; 20462069 (ISSN) ; Shaye, H ; Sharif University of Technology
Royal Society of Chemistry 2015
The potentials of partial least squares regression (PLSR) and multivariate curve resolution alternating least squares (MCR-ALS) are evaluated for the simultaneous determination of diclofenac (DCF), naproxen (NAP), mefenamic acid (MEF) and carbamazepine (CBZ) as target analytes and gemfibrozil (GEM) as an interference in synthetic and real environmental samples. The analysis of first-order UV-Vis spectra is performed using PLSR with different variable selection methods, which include variable importance in projection (VIP), recursive weighted partial least squares (rPLS), regression coefficient (RV) and uninformative variable elimination (UVE), and using MCR-ALS with correlation constraint...
Multivariate curve resolution-particle swarm optimization: A high-throughput approach to exploit pure information from multi-component hyphenated chromatographic signals, Article Analytica Chimica Acta ; Volume 772 , 2013 , Pages 16-25 ; 00032670 (ISSN) ; Ebrahimi Najafabadi, H ; Jalali Heravi, M ; Sharif University of Technology
Multivariate curve resolution-particle swarm optimization (MCR-PSO) algorithm is proposed to exploit pure chromatographic and spectroscopic information from multi-component hyphenated chromatographic signals. This new MCR method is based on rotation of mathematically unique PCA solutions into the chemically meaningful MCR solutions. To obtain a proper rotation matrix, an objective function based on non-fulfillment of constraints is defined and is optimized using particle swarm optimization (PSO) algorithm. Initial values of rotation matrix are calculated using local rank analysis and heuristic evolving latent projection (HELP) method. The ability of MCR-PSO in resolving the chromatographic...
Chemometrics-assisted GC-MS analysis of volatile and semi-volatile constituents of elettaria cardamomum, Article Food Analytical Methods ; Vol. 7, issue. 9 , 2014 , pp. 1745-1754 ; ISSN: 1936-9751 ; Mani-Varnosfaderani, A ; Sharif University of Technology
Multivariate curve resolutions (MCR) along with other chemometric techniques are proposed to improve the analysis of Iranian Elettaria cardamomum (E. cardamom) essential oil with gas chromatography-mass spectrometry (GC-MS). In addition, multivariate curve resolution-alternating least squares (MCR-ALS) is used to obtain pure elution and mass spectral profiles for the components present in each chromatographic segment as well as their relative concentrations. This strategy was also used to overcome the problems of baseline offset, asymmetric peaks, retention time shifts, and overlapped and embedded peaks occurring during GC-MS analysis. The analysis of GC-MS data revealed that 42 components...
Multivariate curve resolution alternating least-squares as a tool for analyzing crude oil extracted asphaltene samples, Article Energy and Fuels ; Volume 26, Issue 9 , 2012 , Pages 5663-5671 ; 08870624 (ISSN) ; Hemmateenejad, B ; Sedghamiz, T ; Khosousi, T ; Ayatollahi, S ; Seiedi, O ; Sayyad Amin, J ; Sharif University of Technology
Asphaltene deposition in the early stage of the oil reservoir life and later during any stimulation process emerges critical problems to the petroleum industry. Deposition of asphaltene aggregates raises strict problems in industries and demands markedly a practical and scientific knowledge of the mechanisms of aggregation and precipitation. Fluorescence emission spectroscopy has been widely used to illuminate the fundamental properties of crude oils and asphaltenes. It proposes analysis of some details of equilibrium, dynamic behavior, and aggregation composition of crude oil under specific condition. In this work, the fluorescence spectra of crude-oil extracted asphaltene samples were...
Second-order calibration for the determination of fatty acids in pomegranate seeds by vortex-assisted extraction-dispersive liquid-liquid micro-extraction and gas chromatography-mass spectrometry, Article RSC Advances ; Volume 5, Issue 15 , 2015 , Pages 11633-11643 ; 20462069 (ISSN) ; Sereshti, H ; Parastar, H ; Sharif University of Technology
Multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was proposed for the simultaneous analysis of eighteen fatty acid methyl esters (FAMEs) in a standard mixture and pomegranate seed sample using vortex-assisted extraction-dispersive liquid-liquid microextraction (VAE-DLLME), followed by gas chromatography-mass spectrometry (GC-MS). The chemometric resolution, identification and quantification of the target FAMEs in the standard mixture and real sample (i.e., the pomegranate seed) were carried out successfully in the presence of some uncalibrated interferences. The lack of fit (LOF) and reverse match factor (RMF) were used for the...
Synthesis, crystal structure, DFT calculation and DNA binding studies of new water-soluble derivatives of dppz, Article Journal of Molecular Structure ; Volume 1145 , 2017 , Pages 141-151 ; 00222860 (ISSN) ; Eslami, A ; Kia, R ; Aleeshah, R ; Sharif University of Technology
Diquaternarization of dipyrido-[2,3-a:2′,3′-c]-phenazine,(dppz) and its analogous dipyrido-[2,3-a:2′,3′-c]-dimethylphenazine,(dppx) using 1,3-dibromopropane afford new water-soluble derivatives of phenazine, propylene-bipyridyldiylium-phenazine (1) and propylene-bipyridyldiylium-dimethylphenazine (2). The compounds have been characterized by means of FT-IR, NMR, elemental analysis and conductometric measurements and their structure were determined by X-ray crystallography. The experimental studies on the compounds have been accompanied computationally by Density Functional Theory (DFT) calculations. The DNA binding properties of both compounds to calf thymus DNA (ctDNA) were investigated by...
A systematic study on the effect of noise and shift on multivariate figures of merit of second-order calibration algorithms, Article Analytica Chimica Acta ; Volume 952 , 2017 , Pages 18-31 ; 00032670 (ISSN) ; Parastar, H ; Sereshti, H ; Olivieri, A ; Tauler, R ; Sharif University of Technology
Elsevier B.V 2017
In the present study, multivariate analytical figures of merit (AFOM) for three well-known second-order calibration algorithms, parallel factor analysis (PARAFAC), PARAFAC2 and multivariate curve resolution-alternating least squares (MCR-ALS), were investigated in simulated hyphenated chromatographic systems including different artifacts (e.g., noise and peak shifts). Different two- and three-component systems with interferences were simulated. Resolved profiles from the target components were used to build calibration curves and to calculate the multivariate AFOMs, sensitivity (SEN), analytical sensitivity (γ), selectivity (SEL) and limit of detection (LOD). The obtained AFOMs for different...
Comparison between two different hemichromes of hemoglobins (HbA and HbS) induced by n-dodecyl trimethylammonium bromide: Chemometric study, Article Colloids and Surfaces B: Biointerfaces ; Volume 63, Issue 2 , 2008 , Pages 183-191 ; 09277765 (ISSN) ; Parastar, H ; Jalali Heravi, M ; Chamani, J ; Chilaka, F. C ; Moosavi Movahedi, A. A ; Sharif University of Technology
The interaction of n-dodecyl trimethylammonium bromide (DTAB) with oxyhemoglobin A and oxyhemoglobin S is investigated using UV-visible absorption spectra and chemometric resolution techniques. Oxyhemoglobins (A and S) induced to partial oxidized form (ferrihemoglobin) by DTAB and finally transform to fully oxidized hemichrome. Hemichrome mole fractions of HbS are more than HbA because of more hydrophobic interaction of DTAB-HbS in second set of binding site relative to DTAB-HbA. The visible spectra between 500 and 650 nm are used for identifying the present components in solution because each species of hemoglobin has a specific spectrum in this region. The number of components and mole...
Second-order calibration for simultaneous determination of pharmaceuticals in water samples by solid-phase extraction and fast high-performance liquid chromatography with diode array detector, Article Chemometrics and Intelligent Laboratory Systems ; Vol. 137, issue , 2014 , pp. 146-154 ; ISSN: 01697439 ; Parastar, H ; Sharif University of Technology
A fast high-performance liquid chromatography-diode array detection (HPLC-DAD) approach combined to solid phase extraction (SPE) as a pre-concentration step is developed for simultaneous determination of five selected pharmaceuticals (carbamazepine, naproxen, diclofenac, gemfibrozil and mefenamic acid) in water samples. The effective factors on the efficiency of SPE procedure are optimized using faced-centered central composite design (FCCD). In addition, multi-response optimization by using Derringer's desirability function is used to find the optimum experimental conditions for extraction of analytes from well and river waters. Due to the complexity of water matrices and the presence of...
Use of gas chromatography-mass spectrometry combined with resolution methods to characterize the essential oil components of Iranian cumin and caraway, Article Journal of Chromatography A ; Volume 1143, Issue 1-2 , 2007 , Pages 215-226 ; 00219673 (ISSN) ; Zekavat, B ; Sereshti, H ; Sharif University of Technology
Gas chromatography-mass spectrometry combined with iterative and non-iterative resolution methods was used to characterize the essential oil components of Iranian cumin and caraway. Orthogonal projection resolution (OPR) as a non-iterative and distance-selection-multivariate curve resolution-alternative least squares (DS-MCR-ALS) as an iterative method were used as auxiliary means to the analysis in the case of overlapping peaks. A total of 19 and 39 components were identified by direct similarity searches for cumin and caraway oils, respectively. These numbers were extended to 49 and 98 components, respectively with the help of chemometric techniques. Major constituents in cumin are...
Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry, Article Journal of Chromatography A ; Volume 1413 , September , 2015 , Pages 117-126 ; 00219673 (ISSN) ; Sereshti, H ; Parastar, H ; Sharif University of Technology
In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9 μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a...
Fuzzy C-means clustering for chromatographic fingerprints analysis: A gas chromatography-mass spectrometry case study, Article Journal of Chromatography A ; Volume 1438 , 2016 , Pages 236-243 ; 00219673 (ISSN) ; Bazrafshan, A ; Sharif University of Technology
Fuzzy C-means clustering (FCM) is proposed as a promising method for the clustering of chromatographic fingerprints of complex samples, such as essential oils. As an example, secondary metabolites of 14 citrus leaves samples are extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The obtained chromatographic fingerprints are divided to desired number of chromatographic regions. Owing to the fact that chromatographic problems, such as elution time shift and peak overlap can significantly affect the clustering results, therefore, each chromatographic region is analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) to address these problems. Then,...
Joint approximate diagonalization of eigenmatrices as a high-throughput approach for analysis of hyphenated and comprehensive two-dimensional gas chromatographic data, Article Journal of Chromatography A ; Volume 1524 , 2017 , Pages 188-201 ; 00219673 (ISSN) ; Parastar, H ; Sharif University of Technology
The objective of the present work is development of joint approximate diagonalization of eigenmatrices (JADE) as a member of independent component analysis (ICA) family, for the analysis of gas chromatography-mass spectrometry (GC–MS) and comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC–MS) data to address incomplete separation problem occurred during the analysis of complex sample matrices. In this regard, simulated GC–MS and GC × GC–MS data sets with different number of components, different degree of overlap and noise were evaluated. In the case of simultaneous analysis of multiple samples, column-wise augmentation for GC–MS and column-wise super-augmentation...
Chromatographic fingerprint analysis of secondary metabolites in citrus fruits peels using gas chromatography-mass spectrometry combined with advanced chemometric methods, Article Journal of Chromatography A ; Volume 1251 , 2012 , Pages 176-187 ; 00219673 (ISSN) ; Jalali Heravi, M ; Sereshti, H ; Mani Varnosfaderani, A ; Sharif University of Technology
Multivariate curve resolution (MCR) and multivariate clustering methods along with other chemometric methods are proposed to improve the analysis of gas chromatography-mass spectrometry (GC-MS) fingerprints of secondary metabolites in citrus fruits peels. In this way, chromatographic problems such as baseline/background contribution, low S/N peaks, asymmetric peaks, retention time shifts, and co-elution (overlapped and embedded peaks) occurred during GC-MS analysis of chromatographic fingerprints are solved using the proposed strategy. In this study, first, informative GC-MS fingerprints of citrus secondary metabolites are generated and then, whole data sets are segmented to some...
Towards obtaining more information from gas chromatography-mass spectrometric data of essential oils: An overview of mean field independent component analysis, Article Journal of Chromatography A ; Volume 1217, Issue 29 , 2010 , Pages 4850-4861 ; 00219673 (ISSN) ; Parastar, H ; Sereshti, H ; Sharif University of Technology
Mean field independent component analysis (MF-ICA) along with other chemometric techniques was proposed for obtaining more information from multi-component gas chromatographic-mass spectrometric (GC-MS) signals of essential oils (mandarin and lemon as examples). Using these techniques, some fundamental problems during the GC-MS analysis of essential oils such as varying baseline, presence of different types of noise and co-elution have been solved. The parameters affecting MF-ICA algorithm were screened using a 25 factorial design. The optimum conditions for MF-ICA algorithm were followed by deconvolution of complex GC-MS peak clusters. The number of independent components (ICs) (chemical...