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Multivariate analysis in combination with pattern recognition procedures has been applied to samples of green and black tea. Discriminant analysis has been used for classification purposes. Aqueous extract, polyphenols, amino acids, caffeine, theobromine and theophylline were used as chemical descriptors.
A new amperometric glucose sensor based on the glucose oxidase immobilized on pyrolytic graphite (PG) modified with tetraammineplatinum(II) chloride (TAPtCl) and 5,10,15,20-tetrakis (4-methoxy-phenyl)-21H,23H-porphine cobalt(II) (TMPPCo) as well as Nafion was studied. The performances amongst the glucose sensors with or without TAPtCl or/and TMPPCo measured with oxygen present in the solution were...
The monomer-dimer equilibrium in several ionic dyes (Methylene Blue, Acridine Orange, Nile Blue A, Neutral Red, Rhodamine 6G and Safranine O) has been investigated by means of UV-Vis spectroscopy. The data have been processed by a recently developed method for quantitative analysis of undefined mixtures, based on simultaneous resolution of the overlapping bands in the whole set of absorption spectra...
A sequential injection spectrophotmetric method for the assay of bromazepam anxiolytic drug has been reported. The method is based on the complexation reaction of bromazepam with iron(II) in hydrochloric acid media and spectrophotometrically measuring the product at λ max =585 nm. A comprehensive chemometrical optimization treatment was successfully utilized for determining the proper optimum...
The identities of the species of chromium(VI) that are present in aqueous solution, their spectra and their equilibria, continue to be a subject of discussion in the literature. In this paper, the composition of the Cr(VI) equilibria was estimated from the UV-vis spectra of dilute potassium dichromate solutions, without any prior knowledge of the quantities of pure components, with the aid of Imbrie...
A singular value decomposition (SVD)-based chemometric method is used for deconvolution of spectral information obtained from a single sample containing an equilibrium system with spectral overlapping at different temperatures. The output of analysis is the association constants at each temperature, thermodynamic parameters and the component spectral profiles. Thermodynamic characterization of charge-transfer...
The problem of a new robust algorithm for estimation of central location has been described in a mathematically simpler way using the fuzzy sets theory. It was compared with ordinary mean estimator and other robust estimators — median, 5% trimmed mean and Huber-, Tukey-, Hampel-, and Andrews-type M-estimators. The performance of Fuzzy 1-means algorithm (FM) proposed is demonstrated by applying it...
In this study, the feasibility of using the in vitro absorption spectra of phytoplankton samples, for determining the relative abundance of specific classes of the phytoplankton, was investigated. Single species cultures of nine algae, representing six phytoplankton classes, were used. Mixtures of algal cultures were also prepared for analysis. In total, 25 samples were examined. Spectra were recorded...
In the present paper, a study on the characterisation of beer samples according to their mineral content has been carried out. Zn, P, B, Mn, Fe, Mg, Al, Sr, Ca, Ba, Na and K were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in 32 beer samples. Lager, dark and low alcoholic content beers were considered. The analysed elements were considered as chemical descriptors...
A chemometric resolution method is described for the identification of nitrogen compounds in crude oil. Prefractionation of crude oil into discrete chemical classes was performed by adsorption column chromatography using small quantities of neutral aluminum oxide and silicic acid. Subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography,...
The monomer-dimer equilibrium of an asymmetric cyanine dye has been investigated by means of UV-Vis spectroscopy. The data have been processed by a recently developed chemometric method for quantitative analysis of undefined mixtures, that is based on simultaneous resolution of the overlapping bands in the whole set of absorption. In this work the dimerization constant of 1-carboxydecyl-4-{3-[3-methyl-3H-benzothiazol-2-ylidene]-propenyl}-quinolini...
The metal content of a number of sparkling wines was determined by atomic spectrometry techniques. Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn by using inductively coupled plasma atomic emission spectrometry (ICP-AES); Cd, Ni and Pb by graphite furnace atomic absorption spectrometry (GFAAS) and As from hydride generation AAS (HGAAS). Two kinds of sparkling wines were studied with D.O. trademark:...
In this paper, it is demonstrated that a single-receptor biosensor can be used to quantitatively determine each analyte in binary mixtures using multivariate data analysis tools based on the dynamic responses received from flow injection peaks. Mixtures with different concentrations of two phenolic compounds, catechol and 4-chlorophenol, were measured with a graphite electrode modified with tyrosinase...
Eleven elements (Zn, P, B, Mn, Mg, Cu, Ca, Ba, Sr, Na and K) were determined by inductively plasma coupled spectrometry in 40 honey samples from different places of Spain and four different botanical origins: Eucalyptus (Eucalyptus sp.), Heather (Erica sp.), Orange-blossom (Citrus sinensis) and Rosemary (Rosmarinus officinalis). K, Ca and P show the higher levels with average concentrations ranged...
The paper provides some linearisation methods presented in modified (Gran I method), extended (pH-static titration) and generalised (Ni method) or corrected versions. Particularly, the modified Gran I method, based on the approximation ln(1+x) ≅ x/(1+x/2), enables (a) significant error inherent in the original Gran I method of equivalence volume V eq evaluation to be avoided, (b) greater portions...
This manuscript discusses the application of chemometrics to the handling of HPLC response data using a model mixture containing ascorbic acid, paracetamol and guaiphenesin. Derivative treatment of chromatographic response data followed by convolution of the resulting derivative curves using 8-points sinx i polynomials (discrete Fourier functions) was found beneficial in eliminating different...
Zinc, boron, iron, magnesium, calcium, sodium and silicon were determined in aniseed drinks by inductively coupled plasma-atomic emission spectrometry (ICP-AES). These elements were considered as chemical descriptors to characterise Spanish-certified aniseed drinks brands of origin. Different pattern recognition (PR) procedures were applied for these purposes. This chemometric study have included...
The concentrations of Cu, Zn, Mn, Fe, K, Ca, Mg, Al, Ba and B in 26 herbal drugs of special importance in phytopharmacy were studied. Flame atomic absorption and emission spectrometry (FAAS, FAES), as well as inductively coupled plasma atomic emission spectrometry (ICP-AES), were applied in this work. The whole procedure, from sample preparation, via dissolution, to measurements, was validated by...
Over the last 20 years there has been an increasing interest in the development of robust systems, both analytical and statistical, to enable the linkage of seizures of illicit drug to each other. Much of this work has concentrated on the analysis of synthetic drugs, such as amphetamine and its analogues. In recent years, the analysis of both organic and elemental impurities as well as isotope ratios...
A combination of mass spectrometry-based electronic nose (MS e_nose) and chemometrics was explored to classify two Australian white wines according to their varietal origin namely Riesling and unwooded Chardonnay. The MS e_nose data were analysed using principal components analysis (PCA), discriminant partial least squares (DPLS) and linear discriminant analysis (LDA) applied to principal components...
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