Eduardo Marchevsky
UNSL Universidad Nacional de San Luis, Quimica, Department Member
Multielemental composition and nutritional value of "dumosa" (Ilex dumosa), "yerba mate" (I. paraguariensis) and their commercial mixture in different forms of use Composición multielemental y valor nutricional de "dumosa" (Ilex dumosa), "yerba mate" (I. paraguariensis) y su mezcla comercial en d...more
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Background/Aim. Quantitative analysis of amoxicillin and clavulanic acid in biological matrices requires sensitive and specific methods which allow determination of therapeutic concentration in ?g/mL range. Analytical methods for... more
Background/Aim. Quantitative analysis of amoxicillin and clavulanic acid in biological matrices requires sensitive and specific methods which allow determination of therapeutic concentration in ?g/mL range. Analytical methods for determination of their concentrations in body fluids described in literature include high performance liquid chromatography coupled to UV detector (HPLC-UV) and liquid chromatography-mass spectrometry (LC-MS). The aim of this study was to develop sensitive and specific ultra performance liquid chromatography/ mass spectrometry (UPLC/MS) method which could be used for the spectral identification and quantification of the low concentrations of amoxicillin and clavulanic acid in the human plasma. Method. A sensitive and specific UPLC/MS method for amoxicillin and clavulanic acid determination was developed in this study. The samples were taken from the adult healthy volunteers receiving per os one tablet of amoxicillin (875 mg) in combination with clavulanic acid (125 mg). Results. Plasma samples were pretreated by direct deproteinization with perchloric acid. Quantification limit of 0.01 ?g/ml for both amoxicillin and clavulanic acid was achieved. The method was reproducible day by day (RSD < 7 %). Analytical recoveries for amoxicillin ranged from 98.82% to 100.9% (for concentrations of 1, 5 and 20 ?g/mL), and recoveries for clavulanic acid were 99,89% to 100.1% (for concentrations of 1, 2 and 5 ?g/mL). This assay was successfully applied to a pilot pharmacokinetic study in healthy volunteers after a single-oral administration of amoxicillin/ clavulanic combination. The determined plasma concentrations of both amoxicillin and clavulanic acid were in the range of the expected values upon the literature data for HPLC-UV and LC-MS methods. Conclusion. The described method provided a few advantages comparing with LC/MS-MS method. The method is faster using running time of 5 minute, has lower limit of quantification (LOQ ) and it could be used in pharmacokinetic studies of both amoxicillin and clavulanic acid.
Research Interests:
CYP2A6 is a human enzyme responsible for the metabolic elimination of nicotine, and it is also involved in the activation of procarcinogenic nitrosamines, especially those present in tobacco smoke. Several investigations have reported... more
CYP2A6 is a human enzyme responsible for the metabolic elimination of nicotine, and it is also involved in the activation of procarcinogenic nitrosamines, especially those present in tobacco smoke. Several investigations have reported that reducing this enzyme activity may contribute to anti-smoking therapy as well as reducing the risk of promutagens in the body. For these reasons, several authors investigate selective inhibitors molecules toward this enzyme. The aim of this study was to evaluate the interactions between a set of organosulfur compounds and the CYP2A6 enzyme by a quantitative structure-activity relationship (QSAR) analysis. The present work provides a better understanding of the mechanisms involved, with the final goal of providing information for the future design of CYP2A6 inhibitors based on dietary compounds. The reported activity data were modeled by means of multiple regression analysis (MLR) and partial least-squares (PLS) techniques. The results indicate that...
The concentrations of 17 non-essential elements (Al, As, Ba, Be, Cd, Ce, Cr, Hg, La, Li, Pb, Sb, Sn, Sr, Th, Ti, and Tl) were determined in brown grain rice samples of two varieties: Fortuna and Largo Fino. The samples were collected from... more
The concentrations of 17 non-essential elements (Al, As, Ba, Be, Cd, Ce, Cr, Hg, La, Li, Pb, Sb, Sn, Sr, Th, Ti, and Tl) were determined in brown grain rice samples of two varieties: Fortuna and Largo Fino. The samples were collected from the four main producing regions of Corrientes province (Argentina). Quantitative determinations were performed by inductively coupled plasma mass spectrometry (ICP-MS), using a validated method. The contents of As, Be, Cd, Ce, Cr, Hg, Pb, Sb, Sn, Th, and Tl were very low or not detected in most samples. The non-essential element levels detected were in line with studies conducted in rice from different parts of the world. In order to characterize the influence of geographical origin in the samples, the following classification methods were carried out: linear discriminant analysis (LDA), k-nearest neighbors (k-NN), partial least squares discriminant analysis (PLS-DA), support vector machine (SVM) and random forests (RF). The best performance was ob...
Research Interests:
Research Interests:
Research Interests:
Research Interests: Algorithms, Analytical Chemistry, Near Infrared, Multivariate Analysis, Concentration, and 15 moreInfrared spectroscopy, Calibration, Method, Gas Chromatography, Accuracy, Analytical Methods, Precision, Oleic Acid, Helianthus, Infrared Spectrometry, Figure of Merit, Diffuse Reflection, Diffuse Reflectance Spectroscopy, Multivariate Calibration, and materia prima
Research Interests:
A new method to determine a mixture for sweetener sodium saccharin and aspartame in commercial noncaloric sweeteners is proposed. A classical full factorial design for standards was used in the calibration step to build the partial... more
A new method to determine a mixture for sweetener sodium saccharin and aspartame in commercial noncaloric sweeteners is proposed. A classical full factorial design for standards was used in the calibration step to build the partial least-squares (PLS-2) model. Instrumental data were obtained by means of UV-visible spectrophotometry. Salicylic acid was used as an internal standard to evaluate the adjustment of the real samples to the PLS model. The concentration of analytes in the commercial samples was evaluated using the obtained model by UV spectral data. The PLS-2 method was validated by capillary zone electrophoresis (CZE), finding in all cases a relative error of less than 11% between the PLS-2 and the CZE methods. The proposed procedure was applied successfully to the determination of saccharin and aspartame in noncaloric commercial sweeteners.
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Research Interests:
Melissa officinalis L., so called "Melissa" or "Toronjil", is a perennial aromatic herb, whose leaves are used in traditional medicine as a carminative, digestive and sedative, both in simple as in mixtures. Meanwhile,... more
Melissa officinalis L., so called "Melissa" or "Toronjil", is a perennial aromatic herb, whose leaves are used in traditional medicine as a carminative, digestive and sedative, both in simple as in mixtures. Meanwhile, Nepeta cataria L., commonly called "Cat mint" or "Toronjil", with some similar properties, often replacing M. officinalis in the market, although their chemical composition is not completely matched, and contains an iridoid potentially toxic (nepetalactone). It is therefore necessary to establish diacritic parameters to differentiate these species, both at crude drug level, mixtures and extracts. Samples from various sources in Argentina were studied and documental specimens are preserved in the Herbarium UNSL. Anatomical sections were analyzed, and quantitative micrographic parameters were obtained, together with HPLC and FTIR spectra from methanolic and aqueous lyophilized extracts. Significant differences were detected in the...
2-[2-(5-Chloropyridyl)azo]-5-dimethylaminophenol (C1DMPAP) is proposed as a metallochromic indicator for zinc. The end-point colour change is from the violet-red of the zinc complex to the brownish-yellow of the indicator. The colour... more
2-[2-(5-Chloropyridyl)azo]-5-dimethylaminophenol (C1DMPAP) is proposed as a metallochromic indicator for zinc. The end-point colour change is from the violet-red of the zinc complex to the brownish-yellow of the indicator. The colour contrast is markedly greater than that for Erio-T.
Research Interests:
An on-line lead preconcentration and determination system implemented with inductively coupled plasma-atomic emission spectrometry (ICP-AES) with ultrasonic nebulization (USN) in association with flow injection was studied. For the... more
An on-line lead preconcentration and determination system implemented with inductively coupled plasma-atomic emission spectrometry (ICP-AES) with ultrasonic nebulization (USN) in association with flow injection was studied. For the preconcentration of lead, a Pb-quinolin-8-ol complex was formed on-line at pH 6.8 and retained on Amberlite XAD-16 resin. The lead was removed from the microcolumn by countercurrent elution with nitric acid. A total enhancement factor of 225 was obtained with respect to ICP-AES with pneumatic nebulization (15.0 for USN and 15.0 for the column). The detection limit for Pb for the preconcentration of a 10 mL wine sample was 0.15 microg/L. The precision for 10 replicate determinations at a Pb level of 25 microg/L was a relative standard deviation of 2.5%, calculated from the peak heights obtained. The calibration graph obtained by using the preconcentration system for lead was linear with a correlation coefficient of 0.9995 for levels near the detection limi...
Research Interests:
The most common mechanism of the so-called multidrug resistance (MDR), is mainly associated with an over expression of P-glycoprotein (Pgp). It is an ATP-dependent transport protein that limits the intracellular accumulation of a variety... more
The most common mechanism of the so-called multidrug resistance (MDR), is mainly associated with an over expression of P-glycoprotein (Pgp). It is an ATP-dependent transport protein that limits the intracellular accumulation of a variety of structurally unrelated compounds within various organs and normal tissues such as kidney, small intestine and the blood brain barrier. Thus, the expression of Pgp has a major impact on the pharmacokinetic profile of many therapeutic agents and therefore, overcoming Pgp-mediated efflux constitutes an attractive means of potentially enhancing their therapeutic efficacy. The flavonoids comprise a large group of polyphenolic compounds that occur in plants and vegetables, and they have been shown to display a wide variety of biological activities. For example, anti-inflammatory, antioxidant, antiallergic, hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities. The interactions between flavonoids and Pgp have also been extensively...
Research Interests:
This work discusses the determination of the provenance of commercial Torrontés wines from different Argentinean provinces (Mendoza, San Juan, Salta and Rio Negro) by the use of UV-vis spectroscopy and chemometric techniques. In order to... more
This work discusses the determination of the provenance of commercial Torrontés wines from different Argentinean provinces (Mendoza, San Juan, Salta and Rio Negro) by the use of UV-vis spectroscopy and chemometric techniques. In order to find classification models, wines (n = 80) were analyzed using UV-Vis region of the electromagnetic spectrum. Principal component analysis (PCA), linear discriminant analysis (LDA) and partial least squares discriminant analysis (PLS-DA) were used to classify Torrontés wines according to their geographical origin. Classification rates obtained were highly satisfactory. The PLS-DA and LDA calibration models showed that 100% of the Mendoza, San Juan, Salta and Rio Negro Torrontés wine samples had been correctly classified. These results demonstrate the potential use of UV spectroscopy with chemometric data analysis as a method to classify Torrontés wines according to their geographical origin, a procedure which requires low-cost equipment and short-ti...
Research Interests:
Research Interests:
ABSTRACT An analytical method for a rapid and nondestructive classification and authentication of whiskies of high commercial value based on trademark and years of aging is presented. Molecular absorption spectroscopy was performed with a... more
ABSTRACT An analytical method for a rapid and nondestructive classification and authentication of whiskies of high commercial value based on trademark and years of aging is presented. Molecular absorption spectroscopy was performed with a minimum manipulation of the sample. Different conditions previous to the chemometric analysis, such as dilution and pH effect, were studied. Fifteen commercial trademarks of whiskies with different years of aging were acquired from the local market. The pattern recognition was performed using principal component analysis (PCA), linear discriminant analysis (LDA), and partial least square discriminant analysis (PLS-DA) to obtain models that allowed the classification and discrimination of whiskies based in trademarks and years of aging, respectively. Results show that by LDA, a mean of 99.15 % of samples was correctly classified according to trademark. On the other hand, by PLS-DA, a 100 % of correct classification and discrimination was achieved with several aging labels (6, 8, 12, and 15 years of aging).
Research Interests:
The concentration of As, Cr, and Pb toxic elements was determined in three species of amaranth seeds:A. hypochondriacus,A. cruentus, andA. dubius. The determinations were carried out by inductively coupled plasma optical atomic... more
The concentration of As, Cr, and Pb toxic elements was determined in three species of amaranth seeds:A. hypochondriacus,A. cruentus, andA. dubius. The determinations were carried out by inductively coupled plasma optical atomic spectroscopy (ICP-OES). The result shows that Cr and As were found in minor concentrations than allowed by the World Health Organization (WHO; 120 and 4 mg kg−1resp.); As (mg kg−1):A. dubius(0.76)A. cruentus(<0.50) andA. hypochondriacus(<0.50); Cr (mg kg−1):A. dubius(8.19)A. cruentus(1.15) andA. hypochondriacus(1.20). However, the concentration of Pb was high:A. dubius(19.04)A. cruentus(30.20) andA. hypochondriacus(35.56) more than the maximum of WHO (10 mg kg−1). To avoid systematic error, recovery and validation studies were performed: recovery test: 102.3%; validation (by standard addition): 96.0–103.1%. Due to the fact that amaranth had been proposed as new food due to its nutraceutical properties, the high concentration of Pb found in this study in...
Research Interests:
The reaction between cadmium and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl DMPAP) in aqueous alcohol media at pH 8.8-10.7 results in an intense violet colour which is stable for at least 8 hr. The composition is 2:1... more
The reaction between cadmium and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl DMPAP) in aqueous alcohol media at pH 8.8-10.7 results in an intense violet colour which is stable for at least 8 hr. The composition is 2:1 reagent:metal and the formation constant (5.29 +/- 0.01) x 10(18). Beer&#39;s law is obeyed up to 1.34 ppm of cadmium at 550 nm. The optimal concentration range (Ringbom) is between 0.16 and 0.72 ppm. The apparent molar absorptivity at 550 nm is (1.20 +/- 0.01) x 10(5) l.mole(-1). cm(-1), making the sensitivity one of the highest known. The interference due to copper(III), iron(III), cobalt(II), nickel(II), gold(III), zinc(II) and manganese(II) can be suppressed.
Research Interests:
Research Interests:
Argentina is an important worldwide wine producer. In this country, there are several recognizable provinces that produce Sauvignon blanc wines: Neuquén, Río Negro, Mendoza, and San Juan. The analysis of the provenance of these white... more
Argentina is an important worldwide wine producer. In this country, there are several recognizable provinces that produce Sauvignon blanc wines: Neuquén, Río Negro, Mendoza, and San Juan. The analysis of the provenance of these white wines is complex and requires the use of expensive and time-consuming techniques. For this reason, this work discusses the determination of the provenance of Argentinean Sauvignon blanc wines by the use of UV spectroscopy and chemometric methods, such as principal component analysis (PCA), cluster analysis (CA), linear discriminant analysis (LDA), and partial least square discriminant analysis (PLS-DA). The proposed method requires low-cost equipment and short-time analysis in comparison with other techniques. The results are in very good agreement with results based on the geographical origin of Sauvignon blanc wines. This manuscript describes a method to determine the geographical origin of Sauvignon wines from Argentina. The main advantage of this method is the use of nonexpensive techniques, such as UV-Vis spectroscopy.
Research Interests:
Résumé/Abstract Thirty two samples of natural honey produced in the province of La Pampa (Argentina) were characterised on the basis of their phosphorous, aluminium, iron, calcium, magnesium and sodium contents. Analytical determinations... more
Résumé/Abstract Thirty two samples of natural honey produced in the province of La Pampa (Argentina) were characterised on the basis of their phosphorous, aluminium, iron, calcium, magnesium and sodium contents. Analytical determinations were carried out using ...
Research Interests:
ABSTRACT
Research Interests:
ABSTRACT
Research Interests:
The characterization of amaranth seeds (Amaranthus spp.) was developed for Amaranthus hypochondriacus, Amaranthus cruentus, and Amaranthus dubius. The elemental concentrations were determined by inductively coupled plasma optic atomic... more
The characterization of amaranth seeds (Amaranthus spp.) was developed for Amaranthus hypochondriacus, Amaranthus cruentus, and Amaranthus dubius. The elemental concentrations were determined by inductively coupled plasma optic atomic spectroscopy. Pattern recognition methods were used for the characterization of seed samples: nonsupervised methods included principal components analysis and cluster analysis; supervised methods were linear discriminant analysis and partial least squares discriminant analysis (PLS-DA). Informed are the concentrations of the following elements: Ag, Al, Ba, Ca, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, S, Sr, V, Zn, and Zr. The lowest mineral content was found in A. hypochondriacus, and the highest one was found in A. dubius. For the classification, selected variables for all multivariate methods were Ba, Cr, Li, Mn, Ni, S, and Sr. Nonsupervised methods allowed us to distinguish between the three species of amaranth; however, PLS-DA supervised methods showed the best prediction ability.
Research Interests:
Research Interests:
... Pr was used as an internal standard in order to evaluate the adjustment of the samples on PLS model, and the recovery of the analytes. The result obtained for honey samples was validated applying ICP-AES method. ... Honey was... more
... Pr was used as an internal standard in order to evaluate the adjustment of the samples on PLS model, and the recovery of the analytes. The result obtained for honey samples was validated applying ICP-AES method. ... Honey was mineralised using the HNO 3 -HClO 4 mixture. ...
Research Interests:
RefDoc Refdoc est un service / is powered by. ...
Research Interests:
Research Interests:
Introduction: "pearl fruit” or “Partridge herb" is a shrub that grows in South America where it is native. Infusions of the aerial parts: leaves and stems are used in folk medicine fundamentally for the treatment of several urinary... more
Introduction: "pearl fruit” or “Partridge herb" is a shrub that grows in South America where it is native. Infusions of the aerial parts: leaves and stems are used in folk medicine fundamentally for the treatment of several urinary disorders. No studies were found about of the mineral content of the aerial parts neither infusion for this species. Objectives: to determine the concentration of mineral elements in aerial parts and infusions of Margyricarpus pinnatus (Lam.) Kuntze. Methods: samples of M. pinnatus in San Luis, Argentina were collected. Concentrations of thirty-two elements in the aerial parts and infusions were determined by optical emission spectroscopy inductively coupled plasma. Results: concentrations in the aerial parts of twenty-four elements were found, while, at infusions only concentrations of fourteen elements were detected. The rest of the elements showed result below the limit of quantification. Extraction efficiency for the order Potassium> Calcium> Chrome> Sodium> Phosphorus> Copper> Magnesium> Boron> Zinc> Silicon> Manganese> Strontium> Aluminum> Iron was registered. The mineral content of the infusions are lower than the limits for the recommended daily intake of minerals. Conclusions: a contribution to the knowledge of the elemental composition of the aerial parts of M. pinnatus and infusions. Daily consumption of the infusions would not be harmful to health.
Research Interests:
Introduction – The chemometric characterisation of two plants frequently used as food and medicinal species, Achyrocline satureioides and Achyrocline venosa (Asteraceae: Gnaphalieae), was carried out based on their mineral composition.... more
Introduction – The chemometric characterisation of two plants frequently used as food and medicinal species, Achyrocline
satureioides and Achyrocline venosa (Asteraceae: Gnaphalieae), was carried out based on their mineral composition. Both
species, known by the common name of ‘marcelas’, are very similar in their morphological features but they have different
medicinal and food properties. Objective – To develop multivariate models for the classification of A. satureiodes and A. venosa based on their mineral content. Methodology – The analytic determinationswere made by means of inductively coupled plasma optical emission spectrometry from aerial parts of the plants. An internal standard was used to evaluate the accuracy in the sample treatment and the recovery of toxic elementswas studied. The multivariate methods used include principal components analysis, cluster analysis and linear discriminant analysis. Results – Classification for both A. satureioides and A. venosa was successful in all cases using only four variables: aluminium, iron, magnesium and sulphur content. The concentrations of the following elementswere determined: Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, La, Mg,Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti,V,Y and Zn. Conclusions – This method is useful to identify both species in raw material in order to detect eventual errors of selection.
satureioides and Achyrocline venosa (Asteraceae: Gnaphalieae), was carried out based on their mineral composition. Both
species, known by the common name of ‘marcelas’, are very similar in their morphological features but they have different
medicinal and food properties. Objective – To develop multivariate models for the classification of A. satureiodes and A. venosa based on their mineral content. Methodology – The analytic determinationswere made by means of inductively coupled plasma optical emission spectrometry from aerial parts of the plants. An internal standard was used to evaluate the accuracy in the sample treatment and the recovery of toxic elementswas studied. The multivariate methods used include principal components analysis, cluster analysis and linear discriminant analysis. Results – Classification for both A. satureioides and A. venosa was successful in all cases using only four variables: aluminium, iron, magnesium and sulphur content. The concentrations of the following elementswere determined: Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, La, Mg,Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti,V,Y and Zn. Conclusions – This method is useful to identify both species in raw material in order to detect eventual errors of selection.
Research Interests:
The aim of this study was to evaluate the mineral content of ten garlic cultivars (all belonging to the Argentinean germplasm and cultivated under identical agro-ecologic conditions). In addition, four of them were planted in three... more
The aim of this study was to evaluate the mineral content of ten garlic cultivars (all belonging to the Argentinean germplasm and cultivated under identical agro-ecologic conditions). In addition, four of them were planted in three different geographic regions, in order to observe how the environment influences the mineral content of cultivars. Mineral profiles (Br, Rb, Na, La, Cr, Cs,