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1

Application of gold electrode modified by thiol layer for determination of some odour compounds - short report

100%
Zielinska D., Radecka H., Radecki J.
Polish Journal of Food and Nutrition Sciences
|
2000
|
tom 09/50
|
nr 2
The micro gold electrode modified by thiol layer was used as a working electrode in the cyclic voltammetry method. This analytical system was used for determining the neutral smell compounds: geraniol and coumarin. The decrease in reduction current value of [Fe(CN)6]-3 ions was observed already at the concentration of 10-5 M of the compound investigated. The dimensions of these changes were different for each compound and their discrimination by the above sensor was possible.
2

Screening of the antioxidant capacity of selected spices by updated analytical strategies

75%
Przygodzka M., Zielinska D., Ciesarova Z., Zielinski H.
Polish Journal of Food and Nutrition Sciences
|
2011
|
tom 61
|
nr Suppl.1
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Determination of the antioxidant activity of rutin and its contribution to the antioxidant capacity of diversified buckwheat origin material by updated analytical strategies

63%
Zielinska D., Szawara-Nowak D., Zielinski H.
Polish Journal of Food and Nutrition Sciences
|
2010
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tom 60
|
nr 4
The antioxidant activity of rutin and selected common buckwheat-originated materials, namely groat, hull, flour and sprouts were measured against stable, non-biological radicals such as 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (ABTS•+) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) using a spectrophotometric assay, against the key reactive oxygen intermediate – superoxide anion radical (O2 –•) with a photochemiluminescence assay (PCL) while reducing capacity was determined with the cyclic voltammetry method (CV). The antioxidant activity was presented independently of the techniques used as TEAC values and then the contribution of rutin to the antioxidant capacity of buckwheat material was calculated. The order of the antioxidant activity of rutin provided by the updated analytical strategy was as follows: CV = DPPH RSA > PCL > ABTS RSA. Buckwheat groat and hull represented low antioxidant capacity samples whilst that of sprouts was ranked as high antioxidant capacity one. The results showed a low contribution of rutin to the antioxidant capacity of buckwheat groat and hull. The highest contribution of rutin to the antioxidant capacity was noted in buckwheat sprouts, especially those produced in light. The specificity of the rank of methods used as CV = DPPH RSA > ABTS RSA > PCL was concluded since the lowest antioxidant gap was provided with CV and DPPH RSA whilst the highest one with ABTS RSA and PCL.
4

Application of voltammetry to determine vitamin C in apple juices

63%
Wawrzyniak J., Ryniecki A., Zembrzuski W.
Acta Scientiarum Polonorum. Technologia Alimentaria
|
2005
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tom 04
|
nr 2
The cyclic voltammetric method, which is based on the redox properties of ascorbic acid, was adopted to determine the concentration of vitamin C in apple juices. Recorded on voltammograms, the oxidation current of ascorbic acid was linearly dependent on the ascorbic acid concentration (a linear calibration curve was found in the range of up to 150 mg ascorbic acid/100 cm3 solution). The standard addition technique was used to determine the ascorbic acid concentration. To verify results, the titrimetric method was used. Differences between concentrations of vitamin C determined using the cyclic voltammetric and titrimetric methods are lower than 1 mg (in comparison to concentrations of ascorbic acid about 50 mg/100 cm3 of juice). The method - easy for automation - can be used directly without special preparation of studied apple juices samples before measurement of the vitamin C concentration.
5
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Evaluation of photochemiluminescent, spectrophotometric and cyclic voltammetry methods for the measurement of the antioxidant capacity: the case of roots separated from buckwheat sprouts

63%
Zielinska D., Wiczkowski W., Piskula M. K.
Polish Journal of Food and Nutrition Sciences
|
2008
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tom 58
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nr 1
This paper describes the use of photochemiluminescence (PCL), spectrophotometric methods (TEAC, FCR reducing capacity) and cyclic voltammetry for the measurement of the antioxidant capacity of roots obtained from dark- and light-grown buckwheat sprouts. A 80% methanol was used for the preparation of extracts originated from roots separated from 6 and 8 DAS (days after seeding) buckwheat sprouts. The 8 days germination period was sufficient to obtain a good quality sprouts with completely removed pericarps and therefore the roots were collected within this period for the experiments. Comparison of the PCL with TEAC assays showed that these methods provided similar values of antioxidant capacity of the roots. Results showed that antioxidant capacity of roots separated from 6 and 8 days sprouts obtained under dark conditions was higher than that noted for roots separated from sprouts planted in light. The FCR reducing capacity values of roots originated from dark and light-grown sprouts were highly correlated with PCL ACL (r= 0.94 and r=1.00, respectively) and TEAC values (r= 0.98 and r=0.99, respectively). The antioxidant capacity of roots obtained from sprouts produced under dark and light conditions evaluated by PCL and TEAC assay gave almost four and three times higher values than that provided by cyclic experiments. In contrast, an excellent agreement was noted between data provided by FCR reducing capacity and antioxidant capacity obtained by cyclic voltammetric experiments indicating that only part of antioxidants present in the root extracts was able to be oxidized on a glassy carbon electrode. The phenolic compounds were the main antioxidants found in root extracts. It was suggested that antioxidant capacity of roots separated from sprouts may be a potential indicator of sprouts resistance against reactive oxygen intermediates resulting in healthy buckwheat sprouts for a consumer.
6

Cyclic voltammetry and fluorescence spectroscopy studies on the effect of polysialic acid on phospholipid model membranes

51%
Janas T., Nowotarski K., Janas T.
Cellular and Molecular Biology Letters
|
1999
|
tom 04
|
nr 2
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