Eduardo J. Marchevsky

Characterisation of two South American food and medicinal plants by chemometric methods based on their multielemental composition.

INTRODUCTIONnThe 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.nnnOBJECTIVEnTo develop multivariate models for the classification of A. satureiodes and A. venosa based on their mineral content.nnnMETHODOLOGYnThe analytic determinations were 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 elements was studied. The multivariate methods used include principal components analysis, cluster analysis and linear discriminant analysis.nnnRESULTSnClassification 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 elements were 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.nnnCONCLUSIONSnThis method is useful to identify both species in raw material in order to detect eventual errors of selection.

Determination of oleic acid in sunflower seeds by infrared spectroscopy and multivariate calibration method.

A method for the determination of oleic acid in sunflower seeds is proposed. One hundred samples of sunflower seeds were analyzed by near-infrared diffuse reflectance spectroscopy (NIRDRS). The direct measures were realized in ground and sifted seeds. The PLS multivariate calibration model was obtained using first derivate absorbance values as response matrix, while the oleic acid concentration matrix was obtained analyzing the seed samples by gas chromatography with a flame ionization detector (GC-FID). The NIRDRS-PLS model was validated externally using unknown samples of sunflower seeds. The accuracy and precision of the method was evaluated using GC as reference method. The following figures of merit (FOM) were obtained: LOD=3.4% (w/w); LOQ=11.3% (w/w); SEN=8x10(-5); SEL=0.15; analytical sensibility (gamma)=1.5 and linear range (LR)=18.1-89.2% (w/w). This method is useful for the fast determination of oleic acid in sunflower seeds and for quality control of raw materials.

Evaluation of macro and microminerals in crude drugs and infusions of five herbs widely used as sedatives

It has been determined the concentration of fourteen micro and macrominerals (Al, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Se, and Zn) in both crude drugs and infusions of Melissa officinalis L., Lamiaceae, Nepeta cataria L., Lamiaceae, Passiflora caerulea L., Passifloraceae, Tilia x moltkei Spath ex C.K. Schneid., Tiliaceae, and Valeriana officinalis L., Caprifoliaceae. These herbs are widely consumed by its sedative properties, either alone or in herb mixtures. All measurements were performed using an inductively coupled plasma optical emission spectrometer (ICP-OES). The products were obtained from regional markets, mainly in San Luis province (Argentina). The estimated daily intake was compared with current recommendations. All products and its infusions were included within the upper tolerable limits for minerals, in trace elements such as toxic elements present at low levels.

Trace element concentrations in commercial gluten-free amaranth bars

Gluten-free foods are specially designed to be consumed by people who suffer from celiac disease or some type of gluten intolerance. Few studies are currently available about trace element contents in gluten-free foods. This study aimed at analyzing the concentrations of 15 trace elements in commercial gluten-free amaranth bars by inductively coupled plasma optical emission spectrometry, after wet digestion by microwave system. The accuracy of the method was determined by the use of a standard reference material (NIST SRM 1570a Spinach Leaves) and recovery experiments, obtaining satisfactory values in all cases. The contents of the investigated trace elements in gluten-free amaranth bars were found to be in the range: Al (3.7–8.1xa0µg/g), Co (0.02–0.07xa0µg/g), Cr (0.05–0.25xa0µg/g), Cu (1.80–6.12xa0µg/g), Fe (7.0–14.5xa0µg/g), Mn (6.5–10.6xa0µg/g), Ni (0.30–0.78xa0µg/g), Pb (0.25–1.12xa0µg/g), Sr (1.4–2.7xa0µg/g), and Zn (4.7–9.8xa0µg/g). Some of the essential trace elements were found to have good nutritional contribution in accordance to daily nutrient recommendations for adults. The concentrations of non-essential elements such as Al, Ni and Sr, were very low in all samples. The levels of toxic elements such as As, Cd, Sb and Tl were not detected in any of the samples, and do not pose any threat to consumers. However, the Pb concentrations were above the safety limits in 8.9xa0% of the studied samples. Therefore, regular monitoring of this toxic metal should be conducted in the future, to ensure the quality of the gluten-free products for human health.

Determining the geographical origin of Sechium edule fruits by multielement analysis and advanced chemometric techniques

This paper describes the determination and evaluation of the major and trace element composition (Al, As, Ba, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Sr and Zn) of Sechium edule (Jacq) Swartz fruits collected from four different places of production in Corrientes province, Argentina. Element concentrations were determined by using inductively coupled plasma optical emission spectrometry (ICP OES) after microwave digestion. The accuracy was confirmed with standard reference material of spinach leaves (NIST, 1570a) and spiking tests. Principal component analysis (PCA), linear discriminant analysis (LDA), k-nearest neighbors (kNN), partial least square-discriminant analysis (PLS-DA) and support vector machine (SVM) were applied to the results for discriminating the geographical origin of S. edule fruits. Finally, the LDA method was found to perform best with up to 90% accuracy rate based on the following elements: Ca, Ba, Cu, Mn, Na, Sr, and Zn.

Non-essential element concentrations in brown grain rice: Assessment by advanced data mining techniques

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 obtained by using RF (96%) and SVM (96%). The results reported here showed the variation in the non-essential element profiles in rice grain depending on the geographical origin.