The use of simulation in the EPR spin probe technique for detection of irradiated seeds

An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses. (C) 2000 Elsevier Science B.V.An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses.We thank Hacettepe University for the financial support of the project 97 01 602 005. We also wish to thank Professor Bekir Aktaş from Gebze Yüksek Teknoloji Enstitüsü for the use of their laboratories for some control measurements

Application of the electron paramagnetic resonance spin probe technique for detection of irradiated wheat

The fast decay of free radicals makes application of traditional electron paramagnetic resonance (EPR) techniques impractical for detection of irradiated wheats when the storage time is longer than 30 days. In this study, therefore, the effects of irradiation on wheat seeds were investigated by using the EPR spin probe technique. The technique is based on the ability of the spin probes to transfer valuable information related to the changes in the structural characteristics of embryo cell membranes caused by irradiation. As a result of irradiation, the environment of the spin probe is modified and this modification can be followed from the recorded spectra. The doses studied were 1.0, 2.5, 10.0, and 20.0 kGy. An aqueous solution of 16- doxyl stearic acid (16-DSA) was used. The embryos were detached using a steel needle and kept in 16-DSA solution for 2.5 hr and washed with distilled water. The spectra of the samples were recorded. The detection of irradiated wheats by this technique was possible at doses of ?2.5 kGy. An important advantage of this approach is that it is applicable even after eight months of storage

An EPR analysis of nitroxide spin probes in ethyl alcohol and tetrahydrofuran

The solutions of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO), 4-hydroxy-TEMPO (TEMPOL) in ethyl alcohol and tetrahydrofurane (THF), 4-amino-TEMPO (TEMPAMINE) in THF were prepared in a concentration range of 0.1 - 10 mM. The EPR (0.3 T) spectra of these samples were recorded at room temperature. Experimental spectra were simulated using high field approximation. For this purpose a FORTRAN program was written and by the use of this program hyperfine coupling constants and intrinsic line widths were determined. Electronic correlation times of the samples were calculated from the line widths and their dependence on the solvent was discussed.The solutions of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO), 4-hydroxy-TEMPO (TEMPOL) in ethyl alcohol and tetrahydrofurane (THF), 4-amino-TEMPO (TEMPA-MINE) in THF were prepared in a concentration range of 0.1-10 mM. The EPR (0.3 T) spectra of these samples were recorded at room temperature. Experimental spectra were simulated using high field approximation. For this purpose a FORTRAN program was written and by the use of this program hyperfine coupling constants and intrinsic line widths were determined. Electronic correlation times of the samples were calculated from the line widths and their dependence on the solvent was discussed.We would like to thank Prof. Dr. Fevzi Koksal from Ondokuz Mayts University-Samsun for permission to use their laboratories for some measurements. We also wish to thank TUBITAK for the financial support of the project