Jana Sádecká

Slovak University of Technology in Bratislava, Presburg, Bratislavský, Slovakia

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Publications (58)91.9 Total impact

  • J. Sádecká · M. Jakubíková · P. Májek · A. Kleinová
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    ABSTRACT: Synchronous fluorescence spectroscopy was used in combination with principal component analysis (PCA) and linear discriminant analysis (LDA) for the differentiation of plum spirits according to their geographical origin. A total of 14 Czech, 12 Hungarian and 18 Slovak plum spirit samples were used. The samples were divided in two categories: colorless (22 samples) and colored (22 samples). Synchronous fluorescence spectra (SFS) obtained at a wavelength difference of 60 nm provided the best results. Considering the PCA-LDA applied to the SFS of all samples, Czech, Hungarian and Slovak colorless samples were properly classified in both the calibration and prediction sets. 100% of correct classification was also obtained for Czech and Hungarian colored samples. However, one group of Slovak colored samples was classified as belonging to the Hungarian group in the calibration set. Thus, the total correct classifications obtained were 94% and 100% for the calibration and prediction steps, respectively. The results were compared with those obtained using near-infrared (NIR) spectroscopy. Applying PCA-LDA to NIR spectra (5500-6000 cm-1), the total correct classifications were 91% and 92% for the calibration and prediction steps, respectively, which were slightly lower than those obtained using SFS.
    No preview · Article · Apr 2016 · Food Chemistry
  • Veronika Urickova · Jana Sadecka · Pavel Majek
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    ABSTRACT: Synchronous fluorescence (SF) spectra measured at constant wavelength differences from 10 nm to 100 nm in the excitation wavelength range 250-350 nm and pattern-recognition methods were used for searching the natural grouping among Slovak juniper-flavoured spirit drinks. The best result was achieved using SF spectra recorded at a constant wavelength difference of 10 nm. Supervised methods were used to classify samples considering two types of classification criteria: distinguishing between drinks from different producers or distillates of different geographical indications and others. The supervised methods were based on two different data sets: the first principal components of the principal component analysis performed on the SF spectra and the SF spectra. Linear discriminant analysis was applied to the first principal components. General discriminant analysis (GDA), k-nearest neighbour (kNN) and support vector machine (SVM) were applied to SF spectra. Regarding different producers, both use of both GDA and SVM resulted in 100% correct classification. Regarding geographical indiciation, 100% correct classification was obtained using GDA.
    No preview · Article · Nov 2015 · Journal of food and nutrition research
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    ABSTRACT: Fluorescence spectroscopy provides rapid profiling of food products and could become an effective tool for authentication when coupled to chemometrics. This study developed a simple method for classifying commercial fruit (apple, apricot, pear, and plum) spirits using synchronous fluorescence spectroscopy. Spectra were collected in the excitation wavelength range from 200 to 500 nm, with constant wavelength differences from 10 to 100 nm, and those obtained at wavelength differences 10, 90, and 100 nm were employed in multivariate analysis. Of samples, 100, 90, and 90 % were properly classified by applying the linear discriminate analysis to the first principal components of the principal component analysis performed on the synchronous fluorescence spectra at wavelength differences 10, 90, and 100 nm, respectively. One hundred percent of samples were properly classified by applying the general discriminate analysis to spectra regardless of wavelength difference used. For the comparison, HPLC analysis was also carried out and discrimination models were generated. The best results were obtained with the general discriminate analysis applied directly to the peak area of common HPLC peaks (correct classification 100 %, training set; 95 %, prediction set).
    No preview · Article · May 2015 · Food Analytical Methods
  • Veronika Uríčková · Jana Sádecká
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    ABSTRACT: The identification of the geographical origin of beverages is one of the most important issues in food chemistry. Spectroscopic methods provide a relative rapid and low cost alternative to traditional chemical composition or sensory analyses. This paper reviews the current state of development of ultraviolet (UV), visible (Vis), near infrared (NIR) and mid infrared (MIR) spectroscopic techniques combined with pattern recognition methods for determining geographical origin of both wines and distilled drinks. UV, Vis, and NIR spectra contain broad band(s) with weak spectral features limiting their discrimination ability. Despite this expected shortcoming, each of the three spectroscopic ranges (NIR, Vis/NIR and UV/Vis/NIR) provides average correct classification higher than 82%. Although average correct classification is similar for NIR and MIR regions, in some instances MIR data processing improves prediction. Advantage of using MIR is that MIR peaks are better defined and more easily assigned than NIR bands. In general, success in a classification depends on both spectral range and pattern recognition methods. The main problem still remains the construction of databanks needed for all of these methods. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Apr 2015 · Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy
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    ABSTRACT: Nitrate in water samples was determined by in-electrode coulometric titration in porous electrode made of vitreous carbon particles coated with copper. The sample was mixed with diluted sulfuric acid containing 1 mmol/L hydrochloric acid, the solution was filled into the cell and electrode and the nitrate ions were directly reduced by constant current to ammonium ions. The stoichiometry of the electrode reaction was found by coulometric and photometric measurements. The detection limit and precision were found to be 0.2 mg/L and 1.7 %, respectively. The interfering effect of high chloride contents was eliminated by precipitating chlorides with silver sulfate. The method was applied for the analysis of various water samples and beverages. The results were in good agreement with data from isotachophoretic and photometric measurements.
    No preview · Article · Mar 2015 · Electroanalysis
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    ABSTRACT: At present, it is necessary to check the quality of many food products in which the content of coumarins is limited. Since a rapid and simple method for the determination of coumarin (COU), 4-hydroxycoumarin (4HC) and dicoumarol (DC) in tea samples was needed, we developed an alternative option to chromatography, i.e., fluorescence spectroscopy with multivariate calibration. The synchronous fluorescence spectra were recorded at constant wavelength differences 70, 80 and 90 nm from 200 to 400 nm. The different experimental parameters affecting the synchronous fluorescence intensities of the analytes were carefully studied and optimized. Partial least squares (PLS) method and multi linear regression (MLR) were compared on determining the concentrations. The best results were obtained by the PLS method on synchronous fluorescence spectra at Δλ = 90 nm. The results from the analysis of herbal tea Melilotus officinalis by synchronous fluorescence spectroscopy with PLS model are equivalent with the results from HPLC. Fisher F- test and Student's t- test confirmed this finding.
    No preview · Article · Jan 2015 · Journal of Fluorescence
  • Michaela Jakubíková · Jana Sádecká · Pavel Májek
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    ABSTRACT: This study introduces a reliable method to detect adulteration of spirit drinks. Excitation-emission matrix (EEM) fluorescence in combination with parallel factor analysis (PARAFAC) and partial least squares (PLS) regression was used to determine the content of water and ethanol in adulterated fruit spirit samples. EEM fluorescence spectra recorded in the emission wavelength range of 315–450 nm and in the excitation wavelength range of 240–305 nm were used for PARAFAC. The model created using PARAFAC-PLS was able to predict the water and ethanol level in adulterated apple spirit with the root mean square error of prediction (RMSEP) values of 1.9 % and 1.8 %, respectively. Regarding adulterated plum spirit, the RMSEP values of 0.7 % and 3.5 % were obtained for water and ethanol, respectively. The aim of this work was to determine whether EEM-PARAFAC can be used to distinguish between plum and apple spirit. Better results were obtained for apple spirit and the method is useful also for water-apple spirit blends.
    No preview · Article · Jan 2015
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    ABSTRACT: The aim of this work was to develop a multivariate method for the rapid determination of caffeine and Class IV caramel in cola-type soft drinks and of caffeine, Class III caramel and riboflavin in energy drinks using synchronous fluorescence spectra. The synchronous fluorescence spectra were recorded at constant wavelength difference 90 nm from 200 to 500 nm. Reference values of analyte concentrations by high performance liquid chromatography (HPLC) with fluorescence detection combined with the standard addition method were used to create the partial least squares (PLS) models. High coefficients of determination (>0.99) were obtained in 0.2–4.2, 0.25–5.25, 0.4–10.0 and 0.007–0.054 mg L−1 range for caffeine, Class III caramel, Class IV caramel and riboflavin, respectively. The PLS models were used to determine the concentration of analytes in different drink samples. The method provided comparable results with those found using the HPLC method.
    No preview · Article · Sep 2014 · Food Chemistry
  • Diana Markechová · Pavel Májek · Jana Sádecká
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    ABSTRACT: The addition of mixed wine spirit to brandy is easy way to adulterate brandy. To avoid the misleading of the consumers, it is necessary to develop reliable method to detect adulteration of brandy. In this work excitation emission matrix fluorescence in combination with parallel factor analysis (PARAFAC) and partial least squares (PLS) regression was used to determine the content of mixed wine spirit in adulterated brandy samples. Excitation emission matrix fluorescence spectra were measured in the emission wavelength range of 485–580 nm and in the excitation wavelength range of 363–475 nm. The model created using PARAFAC–PLS was able to predict the mixed wine spirit level in adulterated brandy with the root mean square error of prediction (RMSEP) value of 1.9% and a square of the correlation (R2) between the reference contents and the predicted values of 0.995.
    No preview · Article · Sep 2014 · Food Chemistry
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    ABSTRACT: The determination has been carried out using excitation- emission matrix fluorescence along with parallel factor analysis (PARAFAC), partial least-squares regression (PLS) and multiple linear regression (MLR). Calibration models consisting of varying spirit composition and brandy were constructed and their accuracy was evaluated through the root-mean-square error of prediction (RMSEP). PLS was a better method compared with MLR due to its lower RMSEP values. The right-angle cell geometry of fluorescence measurements yielded better results than the front-face technique.
    No preview · Article · Jul 2014 · Chemicke Listy
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    ABSTRACT: Brandy, a spirit drink produced from wine (grape), is rich in phenolic acids due to its maturation in wooden barrels. Phenolic acids play a significant role in defining the sensorial characteristics of wines and brandies, and therefore, it is very useful to determine them. Synchronous fluorescence spectra of mixtures containing phenolic acids (gallic, vanillic, syringic and ferulic) and scopoletin have been used for the determination of these compounds by partial least squares (PLS)2. Synchronous fluorescence spectra were collected by simultaneously scanning the excitation and emission monochromator in the excitation wavelength range 200–500 nm, with constant wavelength difference 100 nm between them. The leave-one-out cross-validation method was used to select the optimum number of five PLS2 components (latent variables). The PLS2 model captured for 100 % of variance in the spectral block, and it accounted for 99.34 % of variance in the concentration block. The performance of the model was evaluated by means of root mean square error of cross-validation, root mean square error of prediction and coefficient of determination. The best model was used for the determination of the above-mentioned compounds in brandy samples at concentration levels 2–74 mg L−1 for phenolic acids and 0.06–0.43 mg L−1 for scopoletin. The PLS2 results were found to be in good agreement with those obtained by HPLC method.
    No preview · Article · Mar 2014 · Food Analytical Methods
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    ABSTRACT: The addition of water or ethanol to brandy is an easy way to adulterate brandy. To avoid the misleading of consumers, it is necessary to develop a reliable method to detect the adulteration of brandy. In this work excitation-emission matrix fluorescence in combination with parallel factor analysis (PARAFAC) and partial least squares (PLS) regression was used to determine the content of water, ethanol and methanol in adulterated brandy samples. Excitation-emission matrix fluorescence spectra were measured in the emission wavelength range of 510-600 nm and in the excitation wavelength range of 393-497 nm. The model created using PARAFAC-PLS was able to predict the water, ethanol and methanol level in adulterated brandy with root mean square error of prediction values of 0.24%, 0.20% and 0.22%,respectively, and coefficients of determination of prediction between the reference content and the predicted values of 0.993, 0.997 and 0.995, respectively.
    No preview · Article · Jan 2014 · Analytical methods
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    ABSTRACT: This study compares the use of UV absorption, excitation–emission matrix (EEM) fluorescence and synchronous fluorescence spectroscopy and HPLC with fluorescence detection combined with principal component analysis (PCA), parallel factor analysis (PARAFAC) and linear discriminant analysis (LDA) for distinguishing between commercial samples of Slovak, Belgian, German, Czech and British juniper-flavoured spirit drinks. Overall, 97 %, 88 % and 79 % of samples were properly classified by applying the LDA to the first five principal components of the PCA performed on the synchronous fluorescence spectra (constant wavelength difference 10 nm, 250–450 nm), UV absorption spectra (250–325 nm) and the areas of eight common HPLC peaks, respectively. EEM fluorescence spectroscopy could not discriminate British drinks, while HPLC failed to discriminate Belgian samples. When the areas of eight common HPLC peaks were used as model parameters instead of the five PCs initially used in LDA, the method accuracy was enhanced significantly and 97 % of predicting samples were properly classified.
    No preview · Article · Jan 2014 · Food Analytical Methods
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    ABSTRACT: Luminescence spectrometry was used for classification of brandies and mixed wine spirits. Parallel factor analysis (PARAFAC) was used for exploratory analysis. Then, the linear discriminant analysis applied to PARAFAC scores was studied for discriminating between brandy and mixed wine spirits. In all cases, correct classifications (above 80%) were achieved. In some cases, the right-angle cell geometry of fluorescence measurements yielded better classifications than the front-face technique.
    No preview · Article · Jan 2014 · Chemicke Listy
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    ABSTRACT: 7-R-9-ethyl-6,9-dihydro-6-oxo-[1,2,5]selenadiazolo[3,4-h]quinolines (R =H, COOC2H5, COOCH3, COOH and COCH3, E1h–E5h) and 6-ethyl-6,9-dihydro-9-oxo-[1,2,5]selenadiazolo[3,4-f]quinoline (E1f) were characterized by UV/vis, FT-IR and fluorescence spectroscopy. The electronic absorption spectra of the derivatives E1h–E3h and E5h in the aprotic solvents dimethylsulfoxide (DMSO) and acetonitrile (ACN) reveal low-energy absorption maxima with lmax>400> nm, shifted hypsochromically in water. In DMSO, N-ethyl selenadiazoloquinolones behave as strong fluorescent agents (lem ≥ 550 nm) with the exception of the carboxylic acid derivative E4h which shows only poor emission. Photoinduced reactions of N-ethyl selenadiazoloquinolones were investigated by means of electron paramagnetic resonance (EPR) spectroscopy. Photoexcitation of N-ethyl selenadiazoloquinolones in aerated DMSO with either 385 nm or 400 nm wavelengths, monitored by EPR spin trapping technique, results in the generation of superoxide radical anions; under an inert atmosphere, the generation of methyl radicals originating from the solvent predominates. Upon exposure at either 365 nm, 385 nm or 400 nm, aerated ACN solutions of selenadiazoloquinolones in the presence of sterically hindered amines produce nitroxide radicals via a reaction with photogenerated singlet oxygen. The 7-substituted derivatives of 9-ethyl-6,9-dihydro-6-oxo-[1,2,5]selenadiazolo[3,4-h] quinoline behave as photosensitizers activating molecular oxygen upon photoexcitation and possess the sufficient photochemical stability under the given experimental conditions. The cytotoxic effects of non-photoactivated and UVA photoactivated N-ethyl substituted selenadiazoloquinolones on cancer (human HeLa and murine L1210) and non-cancer (NIH-3T3) cell lines were monitored by the MTT test. The derivative E2h demonstrates the highest cytotoxic/photocytotoxic activity on the neoplastic cell lines.
    Full-text · Article · Jul 2013 · Journal of Physical Organic Chemistry
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    ABSTRACT: Export Date: 18 June 2013, Source: Scopus, Article in Press
    No preview · Conference Paper · Jan 2013
  • Veronika Uríčková · Jana Sádecká · Pavel Májek

    No preview · Article · Jan 2013
  • Diana Markechova · Michaela Tomkova · Jana Sadecka
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    ABSTRACT: Fluorescence excitation-emission matrix (EEM) spectroscopy coupled with parallel factor analysis (PARAFAC) is an established tool of organic matter fingerprinting in aqueous systems. Recently, EEMPARAFAC has been successfully applied in drinking water treatment for simple, rapid, and sensitive evaluation of organic matter removal during different treatment processes. This review describes some recent applications of EEM-PARAFAC in the drinking water industry. It is divided into two sections according to field of application: characterization of organic matter and its removal in drinking water treatment, and determination of contaminants in drinking water.
    No preview · Article · Jan 2013 · Polish Journal of Environmental Studies
  • Jana Sádecká · Jana Tóthová
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    ABSTRACT: Two spectrofluorimetric methods have been developed for the rapid determination of ellagic acid. The first method is based on the complex formation between ellagic acid and borax in methanol solution. The fluorescence of the complex is monitored at an emission wavelength of 456nm with excitation at 383nm. Linear calibration curve was obtained from 2.5×10(-8) to 7.5×10(-7)molL(-1) and the limit of determination was 4×10(-9)molL(-1). The second method is based on the complex formation between ellagic acid and boric acid in ethanol solution. The fluorescence of the complex is monitored at an emission wavelength of 447nm with excitation at 387nm. Linear calibration curve was obtained from 1.25×10(-7) to 1.00×10(-6)molL(-1) and the limit of determination was 7×10(-9)molL(-1). The methods were successfully applied for the determination of ellagic acid in brandy samples. The results were found to be in good agreement with those obtained by HPLC method.
    No preview · Article · Dec 2012 · Food Chemistry
  • Jana Sadecka · Jan Labuda · Veronika Urickova
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    ABSTRACT: This review highlights some nanomaterial-based electrochemical and optical biosensing systems for potential applications in food analysis. Biosensors, analytical devices which combine biorecognition elements and physical transducers for detection of analytes, have become important tools for measuring concentrations of chemical and biological components in food. Nanomaterials such as metallic nanoparticles, quantum dots and carbon nanotubes can improve sensitivity, specificity and speed of analysis and can stimulate the use of such devices in food laboratories.
    No preview · Article · Aug 2012 · Chemicke Listy