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A new equation for converting EC50 into TEAC values and TEAC into EC50 is presented in this paper. The model was fitted to 180 data points of electron paramagnetic resonance (EPR) spectroscopy measurements of various food products. The model was tested basing on 75 EPR spectroscopy measurements. Moreover, the equation was tested on literature data. The determination coefficient between EC50cal and EC50exp was found to be R2 = 0.9762, while the determination coefficient between TEACcal and TEACexp was found to be R2 = 0.9686. Based on obtained results it can be concluded that the proposed model for converting EC50 into TEAC values and TEAC into EC50 values works properly. This will enable a comparison of the antioxidant properties of products identified in literature through the use of different parameters (TEAC, EC50).

The antioxidant properties of various kinds of the traditional Polish alcoholic beverage nalewka were investigated using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR) and ultraviolet–visible (UV–vis) spectroscopy. The antioxidant capacity was measured by EPR spectroscopy in μmol Trolox (TE) in a 100 mL nalewka sample. The total phenolic content was measured by Folin–Ciocalteu (FC) assays while aromatic proton content ( H ar ) was determined by NMR spectroscopy; subsequently the correlation among these values was explored. All of the investigated nalewkas exhibited antioxidant properties. The values of Trolox equivalent antioxidant capacity (TEAC DPPH ) were in the range 45–1045 μmol TE/100 mL. It was found that the value of the TEAC DPPH corresponded to the TP ( r = 0.96) and H ar ( r = 0.95). Moreover, the TEAC DPPH values depended on the kinds of fruits used for nalewkas’ preparation.

The antioxidant properties of various kinds of beers were investigated using electron paramagnetic resonance (EPR) spectroscopy. This was possible by measuring the changes in the intensity of the EPR spectrum that resulted from the interaction of the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl) with the antioxidants found in a beer sample. The antioxidant capacity was then presented in Trolox Equivalents, e.g. μM trolox in a beer sample of 100 ml. The influence of the type, colour, the content of the extract and alcohol on the antioxidant activities of commercial beer samples was investigated using two-way hierarchical clustering and analysis of variance. The results showed that all of the beers investigated exhibit antioxidant properties. By performing an analysis of variance, it was found that the value of the antioxidant capacity significantly (0.05 level of significance) depends on the content of the extract and the colour of the beer. It seems that additives also influence the antioxidant properties to some extent, but neither the alcohol content nor the kind of fermentation affects the antioxidant properties of beer.

The occurrence of Total P (P-Tot) and the mineral forms of P (P-Min) in sediments from Goczalkowice Reservoir were investigated using inductively coupled plasma-optical emission spectrometer (ICP-OES). The method is based on sequential extractions of the sediment samples, each releasing four forms of inorganic P: loosely bound P, P bound to Al (P-Al), P bound to Fe (P-Fe) and P bound to Ca (P-Ca). Sediment samples for studies presented in this work were collected in April, August and November of 2009 from four sites of the Goczalkowice Reservoir. Significant variations in the P forms with sediment grain size were observed. The most abundant form of inorganic P in the bottom sediment was P-Fe. Other P forms were as follows: P-Ca > P-Al > loosely bound-P. Moreover, P compounds were studied using 31 P NMR. It was found that the predominant form was inorganic orthophosphate.

The antioxidant properties of samples of different kinds of commercially available alcoholic beverages were investigated by electron paramagnetic resonance (EPR) spectroscopy. This analytical technique is chiefly designed to enable accurate detection of free radicals. The determination of antioxidant activity by the EPR method is conducted by measuring the changes of the intensity of the EPR spectrum of stable radicals, which results from their interaction with antioxidants. Antioxidant capacity of alcoholic beverages samples was assessed with the use of the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH ). The highest antioxidant activity was found in red wines, followed by a blend of wine and brandy and then by whiskies, whereas plain vodkas and gin showed negative values of antioxidant activity. From our studies it can be concluded that the value of antioxidant capacity depends on the polyphenolic content, the time and method of ageing, as well as on the flavour and colour additives.

Goczalkowice Reservoir is the biggest water reservoir in the south of Poland. For our studies bottom sediments were collected from eight different places of the reservoir at various seasons of the year. EPR spectroscopy was applied to analyse both quantitatively and qualitatively the humic acids (HA) present in the samples. EPR spectra of the extracted HA exhibited broad lines from the paramagnetic metal ions and narrow lines from free radicals. The values of the free radical concentration obtained for HA amounted to 1.14–13.6 × 1016 spin g −1 depending on the season and the place of sample collection. The values of the g factor obtained for HA were of the range 2.0027–2.0035. The EPR studies show that HA extracted from bottom sediment collected at various points of the Goczalkowice Reservoir exhibit similar physical–chemical properties. It was also observed that the depth of the reservoir affects the content of the oxygen functional groups as well as the free radical concentration in HA. The identification of the functional groups was done by means of IR. UV/VIS spectroscopy was used to estimate the maturity of the HA.

The course of the humification process of sewage sludge collected from three biologic-mechanical treatment plants with different treatment technologies was studied. The maturity of sewage sludge and its usefulness for agricultural purposes was also discussed. The physical-chemical properties of humic acids extracted from sewage sludge received from comparable stages of sludge purification were described. Changes of the sludge properties during sewage purification and the progress of the humification process were investigated with EPR, IR and UV/VIS spectroscopic methods. The content of the elements and the carboxylic groups in humic acids extracted from each stage of the sewage treatment were also determined. It was found that the humification processes take place in all three treatment plants but with different intensities resulting from the differences in the individual cleaning processes in these plants. The most intensive changes of physical-chemical parameters in the extracted humic acids were observed in the anaerobic digester where mesophilic fermentation occurs. The sludge oxygenation processes also significantly affect the course of the humification process during sewage treatment.

Comparison of the physico-chemical properties was carried out for humic acids extracted from sewage sludge and bottom sediments. The isolated humic acids were investigated by means of EPR, IR, UV/vis spectroscopic methods and elementary analysis AE. On the basis of earlier studies it was stated that humic acids extracted from sewage sludge can be divided into humic acids extracted from raw sewage sludge and from sewage sludge after the digestion process. The digestion process was found to have the most significant effect on the physico-chemical properties of humic acids extracted from sludge during sewage treatment. Humic acids extracted from sewage sludge had higher free radical concentration than humic acid extracted from bottom sediments. Values of the g -factor were similar for all studied samples. However, it is noteworthy that g -factor values for humic acid extracted from raw sewage sludge and from bottom sediments were lower in comparison to the humic acid extracted from sewage sludge after the fermentation processes. The IR spectra of all studied humic acids confirmed the presence of functional groups characteristic for humic substances. It was also observed that humic acids extracted from bottom sediments had a more aromatic character and contained less carbon, nitrogen and hydrogen than those extracted from the sewage sludge.

In 2005 the treatment plant in Sosnowiec Zagorze was modernized and the processes of nitrification and denitrification were introduced. The study of the biological treatment influence on the course of the humification process was conducted for the sewage sludge received from each stage of sewage purification. The extracted humic-like substances (HA) were investigated by the use of the spectroscopic and analytical methods. The concentration of free radicals and the g -factor was determined with EPR, the presence of the characteristic functional groups was confirmed with IR spectroscopy, whereas the aromatisation of HA was estimated by 13 C NMR method. The results obtained were compared with those for HA extracted from sewage sludge before modernization [1] . It was found that the processes of biological treatment have a significant influence on the changes of the chemical elements in the extracted HA. The HA obtained after modernization are nitrogen-rich (about 9%), in particular after the nitrification and denitrification processes. However, nitrification and denitrification processes only slightly affect the free radical concentration and the g -factor values.

The humic acids extracted from sludge collected from the digestion chamber and the sludge drying beds were studied. The sludge samples were collected, dried and humic acids were extracted. The progress of the humification processes was studied with EPR, IR and NMR spectroscopic methods. For extracted humic acids, concentration of free radicals and g factor was determined with EPR. The presence of characteristic functional groups was confirmed with IR and NMR spectroscopy. To study the changes in content of the elements, the elemental analysis was performed to determine the percentage of carbon, hydrogen, nitrogen, sulfur and oxygen. Taking all the obtained results into account it was found that on the sewage drying beds, humification processes take place in the sludge. In the first two weeks when the sludge on the drying beds an intensive enrichment of humic acids in free radicals takes place. This is the result of the intensive humification process course after the stage in the fermentation chamber where the mesophilic fermentation takes place. Moreover, the humidity of sludge influences the intensive development of free radical concentration at the beginning of the storing period, whereas the humification processes still continue.